diff --git a/.github/workflows/test-suite.yaml b/.github/workflows/test-suite.yaml
index 18b02696ec..0ea9cd70c6 100644
--- a/.github/workflows/test-suite.yaml
+++ b/.github/workflows/test-suite.yaml
@@ -84,9 +84,13 @@ jobs:
     # (two more were cancelled by newer pushes). In merge-queue run
     # 40541059060 the cancelled job failed Result once the shards had
     # finished, which took that pull request out of the queue. 45 minutes
-    # leaves room for a slow runner and still stops a hung job; Result
-    # waits about an hour for the shards anyway.
-    timeout-minutes: 45
+    # was then not enough either: on 29 October jobs were cancelled at it
+    # after every test had passed, with the process still alive 11 and 18
+    # minutes after pytest's summary (runs 40895005971 and 40917254004).
+    # The runner most likely runs short of memory, because every case's
+    # simulation is kept to the end (#2741). 75 minutes matches the Python
+    # shards, which Result waits for anyway, until the cases are released.
+    timeout-minutes: 75
     steps:
       - name: Checkout repo
         uses: actions/checkout@v6
diff --git a/changelog.d/2749.added.md b/changelog.d/2749.added.md
new file mode 100644
index 0000000000..0ef3999318
--- /dev/null
+++ b/changelog.d/2749.added.md
@@ -0,0 +1 @@
+Added the company car and car fuel benefits in kind from 2020-21 (ITEPA 2003 ss. 120 to 152), with the s. 139 appropriate percentages to 2029-30, person inputs for the company car, and Class 1A NICs on both benefits in `ni_employer` and `total_national_insurance`; the benefits are taxed through `taxable_employment_income` and kept out of Class 1 earnings, means-tested earnings and student loan repayment income, and the `company_car_tax_rise_2030` scenario applies Budget 2026's one-point rise for 2030-31.
diff --git a/docs/book/assumptions/employer-ni-incidence.md b/docs/book/assumptions/employer-ni-incidence.md
index 78fadb32a6..01187806c3 100644
--- a/docs/book/assumptions/employer-ni-incidence.md
+++ b/docs/book/assumptions/employer-ni-incidence.md
@@ -62,6 +62,19 @@ The response amounts enter `household_tax`; those same variables are not added t
 and [capital](https://github.com/PolicyEngine/policyengine-uk/blob/b4dbaf57a4ebb1d1f0ba5f7a384795422828db75/policyengine_uk/variables/contrib/policyengine/employer_ni/employer_ni_response_capital_incidence.py)
 allocation formulas.
 
+## Secondary Class 1 only
+
+All three channels cover secondary Class 1 contributions. `ni_employer` also
+holds Class 1A contributions on benefits in kind (`ni_class_1a`), but
+`employer_cost`, `baseline_employer_cost` and `adjusted_employer_cost` leave
+them out, as they leave out the benefits themselves. No household bears
+Class 1A or a change in it, whether the change comes from the benefits (as
+with a rise in the company car appropriate percentages) or from the employer
+rate, which Class 1A follows (SSCBA 1992 s. 10(5)). Such a reform raises
+`gov_tax` by its Class 1A change on top of what households pay. Passing
+Class 1A through these channels is
+[#2752](https://github.com/PolicyEngine/policyengine-uk/issues/2752).
+
 ## Measures and aggregation
 
 Report these quantities separately:
diff --git a/docs/book/programs/gov/hmrc/company-car-benefit.md b/docs/book/programs/gov/hmrc/company-car-benefit.md
new file mode 100644
index 0000000000..cd17d0b8f3
--- /dev/null
+++ b/docs/book/programs/gov/hmrc/company-car-benefit.md
@@ -0,0 +1,149 @@
+# Company car and car fuel benefits
+
+A car an employer makes available for an employee's private use is a
+benefit in kind: its cash equivalent is taxed as employment income
+([ITEPA 2003 s. 120][s120]), and so is fuel provided for its private use
+([s. 149][s149]). The employer pays Class 1A National Insurance on both
+([SSCBA 1992 s. 10][sscba10]). The model calculates both benefits from
+2020-21.
+
+## Inputs
+
+Each person can have one company car. The inputs default to no car, so a
+simulation that sets none of them is unchanged.
+
+| Input | Meaning |
+| --- | --- |
+| `company_car_list_price` | List price of the car and its accessories; zero means no company car |
+| `company_car_capital_contributions` | Capital sums the employee has contributed, this year and earlier |
+| `company_car_co2_emissions` | CO2 emissions figure in g/km (0 for a car that cannot emit CO2) |
+| `company_car_electric_range` | Electric range figure in miles |
+| `company_car_fuel_type` | Fuel type (the `CarFuelType` enum also used for vehicle excise duty) |
+| `company_car_registered_from_6_april_2020` | First registered on or after 6 April 2020 (matters in 2020-21 and 2021-22 only) |
+| `company_car_availability` | Share of the tax year the car is available (default 1) |
+| `company_car_private_use_payments` | Payments for private use |
+| `company_car_private_fuel_provided` | Fuel provided for private use and not made good in full |
+
+The `car_*` inputs describe the person's own car for vehicle excise duty
+and play no part here.
+
+Data that fills these inputs needs to know three things:
+
+- **Set the CO2 figure with the list price.** The model cannot tell a
+  missing figure from 0 g/km, so a car with a list price and no CO2 figure is
+  taxed at the zero-emission rate. A car of the `ELECTRIC` fuel type is taken
+  to emit 0 g/km whatever figure is entered.
+- **Keep the benefits out of pay.** `employment_income` must not also hold
+  them, or they are taxed twice and wrongly bear employee NICs. The SPI's
+  EPB (expenses payments and benefits in kind) includes them, so a dataset
+  that adds EPB to pay, as policyengine-uk-data's SPI records do, must take
+  the car and car fuel benefits out of it.
+- **Projected years.** The list price, capital contributions and payments
+  for private use grow with CPI when a dataset is projected to later years.
+  CPI stands in for a new-car price index, which the OBR does not forecast.
+
+## Calculation
+
+`company_car_appropriate_percentage` applies [s. 139][s139]: a rate for
+0 g/km, rates for 1 to 50 g/km by electric range (one rate from 2028-29),
+a rate for each band from 51-54 to 70-74 g/km (65-74 g/km from 2028-29),
+and from 75 g/km a base rate plus one point for each full 5 g/km, up to the
+maximum. A diesel car not meeting the Euro 6d (RDE2) standard adds 4 points,
+within the maximum ([s. 141][s141]); a car that cannot emit CO2 takes no
+supplement. In 2020-21 and 2021-22 a car first registered on or after
+6 April 2020 takes the lower rates of s. 139A (Finance Act 2020 ss. 9 and
+10). The appropriate percentage is zero for a person without a company car
+(`has_company_car`).
+
+`company_car_benefit` follows the steps of [s. 121][s121]: the price, less
+capital contributions up to £5,000, times the appropriate percentage,
+reduced in proportion to the days the car is unavailable, less payments for
+private use, and never below zero. `car_fuel_benefit` is the appropriate
+percentage of the car fuel benefit charge multiplier ([s. 150][s150]),
+reduced in proportion to the days the car is unavailable. It is nil for a
+car that cannot emit CO2. `benefits_in_kind` adds the two.
+
+## Where the benefits go
+
+- **Income tax.** `taxable_employment_income` adds `benefits_in_kind`, so the
+  benefits reach income tax, at Scottish rates for a Scottish taxpayer, and
+  adjusted net income: the personal allowance taper, the High Income Child
+  Benefit Charge, and the £100,000 limits of Tax-Free Childcare and the
+  extended childcare entitlement. They count as relevant UK earnings for the
+  limit on pension tax relief (HMRC PTM044100).
+- **Not student loan income.** Student loan repayments and the Plan 2
+  interest rate leave the benefits out: Self Assessment excludes Chapter 6
+  car benefits ([SI 2009/470 reg. 29(4)(e)][sl29]), and PAYE deducts
+  repayments from Class 1 earnings (reg. 41).
+- **Not earnings for Class 1 or the means tests.** The benefits are not in
+  `employment_income` or `employment_benefits`, so employee Class 1 NICs and
+  the earnings of Universal Credit ([UC Regulations 2013 reg. 55(2)(a)][uc55]),
+  Housing Benefit (HB Regulations 2006 reg. 35(2)(a)) and Council Tax
+  Reduction leave them out. Those tests still deduct the income tax on them,
+  which is tax paid in respect of the employment (reg. 55(5)(b)) and which
+  PAYE collects from pay. Universal Credit takes earnings as the lowest slice
+  of income, so it deducts all of that tax. Housing Benefit and Council Tax
+  Reduction deduct earnings' share of the person's tax, and count the
+  benefits with pay in that share; with other income, part of the tax on the
+  benefits falls on the other income, as part of the tax on pay does. The
+  Childcare Offer for Wales's gross income lists its sources one by one, and
+  benefits in kind are not among them.
+- **Employer National Insurance.** `ni_class_1a` is the Class 1A percentage
+  of `benefits_in_kind`, and `ni_employer` adds it to secondary Class 1, so it
+  reaches `gov_tax`. The Class 1A percentage is the secondary percentage for
+  the year, except 14.53% in 2022-23.
+- **No household bears Class 1A.** `employer_cost`, and the employer NI
+  incidence variables that recompute it, cover pay and secondary Class 1
+  only. So the fixed-cost pay response and the capital and consumer
+  channels leave out Class 1A and any change in it: it stays with employers
+  as revenue. A reform that changes Class 1A, such as the 2030-31 rise below
+  or a rise in the employer rate, raises `gov_tax` by more than it lowers
+  household incomes. Passing Class 1A through like secondary Class 1 is
+  [#2752](https://github.com/PolicyEngine/policyengine-uk/issues/2752).
+
+## 2030-31
+
+Finance Act 2025 s. 6 sets the rates for 2029-30 and subsequent tax years,
+so the baseline keeps them for 2030-31: 9% for 0 g/km, 19% for 1 to 50 g/km
+and a 39% maximum. Budget 2026 raises every rate for 2030-31 by one point, to
+a maximum of 40%, to be legislated in Finance Bill 2026-27. The
+`company_car_tax_rise_2030` scenario applies that rise:
+
+```python
+from policyengine_uk import Simulation
+from policyengine_uk.scenarios import company_car_tax_rise_2030
+
+reformed = Simulation(situation=situation, scenario=company_car_tax_rise_2030)
+```
+
+`policyengine_uk.scenarios.company_car_tax_rise_2030.COMPANY_CAR_TAX_RISE_2030`
+holds the same changes as a parameter-changes dictionary.
+
+The car fuel benefit charge multiplier is in the baseline for 2027-28 at the
+£30,200 Budget 2026 announced, before the Treasury order is made. That is the
+annual CPI uprating, which the Budget does not score, so a pre-Budget
+baseline has it too; the 2030-31 rise is a policy decision Budget 2026 scores
+(Table 6.1, row 86). The fuel part of the rise depends on the multiplier.
+
+## Not modelled
+
+- Vans and van fuel (ITEPA 2003 s. 154 onwards).
+- Optional remuneration arrangements (s. 120A), shared cars (s. 148) and
+  pool cars (s. 167).
+- Classic cars (s. 147), cars without a CO2 emissions figure (s. 140) and
+  cars first registered before 1 January 1998 (s. 142).
+- Fuel provided for only part of the year (s. 152(2)).
+- Other benefits in kind.
+
+The survey data does not fill these inputs yet, so a population run scores
+the company car benefits at zero until a dataset does.
+
+[s120]: https://www.legislation.gov.uk/ukpga/2003/1/section/120
+[s121]: https://www.legislation.gov.uk/ukpga/2003/1/section/121
+[s139]: https://www.legislation.gov.uk/ukpga/2003/1/section/139
+[s141]: https://www.legislation.gov.uk/ukpga/2003/1/section/141
+[s149]: https://www.legislation.gov.uk/ukpga/2003/1/section/149
+[s150]: https://www.legislation.gov.uk/ukpga/2003/1/section/150
+[sscba10]: https://www.legislation.gov.uk/ukpga/1992/4/section/10
+[sl29]: https://www.legislation.gov.uk/uksi/2009/470/regulation/29
+[uc55]: https://www.legislation.gov.uk/uksi/2013/376/regulation/55
diff --git a/policyengine_uk/data/fiscal_partition.yaml b/policyengine_uk/data/fiscal_partition.yaml
index f242470b4a..1a9744700e 100644
--- a/policyengine_uk/data/fiscal_partition.yaml
+++ b/policyengine_uk/data/fiscal_partition.yaml
@@ -743,6 +743,7 @@ exclusions:
   - {variable: employer_ni_fixed_employer_cost_change, kind: change_measure, head: nics_employer, note: "The wage change from an employer NI reform; employment_income already adds it."}
   - {variable: salary_sacrifice_broad_base_haircut, kind: change_measure, head: nics_employer, note: "A wage change employment_income already adds."}
   - {variable: ni_class_1_employer, kind: component, head: nics_employer}
+  - {variable: ni_class_1a, kind: component, head: nics_employer}
   - {variable: salary_sacrifice_pension_ni_employee, kind: measure_within, head: nics_individual, note: "The excess sacrifice is added back to ni_class_1_income, so Class 1 already charges it."}
   - {variable: salary_sacrifice_pension_ni_employer, kind: measure_within, head: nics_employer, note: "As above, for employer Class 1."}
   - {variable: tax, kind: composite, spans: [income_tax, nics_individual]}
diff --git a/policyengine_uk/data/uprating_indices.yaml b/policyengine_uk/data/uprating_indices.yaml
index ee591c95de..5e28db57dd 100644
--- a/policyengine_uk/data/uprating_indices.yaml
+++ b/policyengine_uk/data/uprating_indices.yaml
@@ -46,6 +46,11 @@ gov.economic_assumptions.yoy_growth.obr.consumer_price_index:
 - childcare_expenses
 - clothing_and_footwear_consumption
 - communication_consumption
+# Company car prices and the payments that go with them. CPI stands in for
+# a new-car price index, which the OBR does not forecast.
+- company_car_capital_contributions
+- company_car_list_price
+- company_car_private_use_payments
 - education_consumption
 - esa_contrib_reported
 - esa_income_reported
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/README.md b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/README.md
new file mode 100644
index 0000000000..b8ccc9c907
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/README.md
@@ -0,0 +1 @@
+# Benefits in kind
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/car_fuel/README.md b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/car_fuel/README.md
new file mode 100644
index 0000000000..624e1ad42a
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/car_fuel/README.md
@@ -0,0 +1 @@
+# Car fuel
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/car_fuel/multiplier.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/car_fuel/multiplier.yaml
new file mode 100644
index 0000000000..97e9c97cfa
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/car_fuel/multiplier.yaml
@@ -0,0 +1,64 @@
+description: Amount to which the company car's appropriate percentage is applied to give the cash equivalent of fuel provided for its private use (the car fuel benefit charge multiplier).
+# The Treasury sets this by order under ITEPA 2003 s. 170(5); no statute
+# indexes it. The 2027-28 figure is announced: Budget 2026 OOTLAR paragraph
+# 2.6 gives £30,200 (September CPI uprating), and the Treasury order is not
+# yet made. It is in the baseline although the Budget 2026 rise in the
+# appropriate percentages for 2030-31 is not: that rise is a policy decision
+# Budget 2026 scores (Table 6.1, row 86), while this is the annual CPI
+# uprating, which the Budget lists among its other announcements and does
+# not score, so a pre-Budget baseline has it too. From 2028-29 the values
+# are a CPI projection, as the government has uprated the figure by
+# September CPI each year; none is announced.
+values:
+  2020-04-06:
+    value: 24_500
+    metadata:
+      reference:
+        - title: The Van Benefit and Car and Van Fuel Benefit Order 2020 (SI 2020/199) art. 2
+          href: https://www.legislation.gov.uk/uksi/2020/199/article/2/made
+  2021-04-06:
+    value: 24_600
+    metadata:
+      reference:
+        - title: The Van Benefit and Car and Van Fuel Benefit Order 2021 (SI 2021/248) art. 2
+          href: https://www.legislation.gov.uk/uksi/2021/248/article/2/made
+  2022-04-06:
+    value: 25_300
+    metadata:
+      reference:
+        - title: The Van Benefit and Car and Van Fuel Benefit (No. 2) Order 2021 (SI 2021/1422) art. 2
+          href: https://www.legislation.gov.uk/uksi/2021/1422/article/2/made
+  2023-04-06:
+    value: 27_800
+    metadata:
+      reference:
+        - title: The Van Benefit and Car and Fuel Benefit Order 2022 (SI 2022/1288) art. 2 (tax year 2023-24 and subsequent tax years)
+          href: https://www.legislation.gov.uk/uksi/2022/1288/article/2/made
+  2025-04-06:
+    value: 28_200
+    metadata:
+      reference:
+        - title: The Van Benefit and Car and Van Fuel Benefit Order 2024 (SI 2024/1349) art. 2(2)
+          href: https://www.legislation.gov.uk/uksi/2024/1349/article/2/made
+  2026-04-06:
+    value: 29_200
+    metadata:
+      reference:
+        - title: The Van Benefit and Car and Van Fuel Benefit Order 2025 (SI 2025/1254) art. 2(2)
+          href: https://www.legislation.gov.uk/uksi/2025/1254/article/2/made
+  2027-04-06:
+    value: 30_200
+    metadata:
+      reference:
+        - title: Budget 2026, overview of tax legislation and rates, paragraph 2.6
+          href: https://www.gov.uk/government/publications/budget-2026-overview-of-tax-legislation-and-rates-ootlar/budget-2026-overview-of-tax-legislation-and-rates-ootlar
+metadata:
+  unit: currency-GBP
+  period: year
+  label: Car fuel benefit charge multiplier
+  uprating: gov.economic_assumptions.indices.obr.consumer_price_index
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 150(1)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/150
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 170(5)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/170
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/README.md b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/README.md
new file mode 100644
index 0000000000..b335b878d6
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/README.md
@@ -0,0 +1 @@
+# Company car
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/README.md b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/README.md
new file mode 100644
index 0000000000..36786a1ddb
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/README.md
@@ -0,0 +1 @@
+# Appropriate percentage
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/co2_band.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/co2_band.yaml
new file mode 100644
index 0000000000..88c601b42b
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/co2_band.yaml
@@ -0,0 +1,78 @@
+description: Appropriate percentage for a company car with a CO2 emissions figure of 51 to 74 g/km, by that figure rounded down to a whole number.
+# Finance Act 2025 s. 5 merges the 65-69 and 70-74 bands into one 65-74 band
+# from 2028-29, so the last two brackets have the same amount from then.
+# For 2020-21 and 2021-22 these are the rates for cars first registered
+# before 6 April 2020; registered_from_6_april_2020 holds the s. 139A rates.
+# The tax year 2030-31 keeps 2029-30's rates. Budget 2026 announced one
+# point more in every band; the company_car_tax_rise_2030 scenario applies it.
+metadata:
+  type: single_amount
+  threshold_unit: g/km
+  amount_unit: /1
+  period: year
+  label: Company car appropriate percentage by CO2 emissions, 51 to 74 g/km
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(1) and (2)(a)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
+    - title: Finance (No. 2) Act 2017 s. 2(2) (tax years 2020-21 to 2024-25)
+      href: https://www.legislation.gov.uk/ukpga/2017/32/section/2/enacted
+    - title: Finance Act 2023 s. 11 (tax years 2025-26, 2026-27 and 2027-28)
+      href: https://www.legislation.gov.uk/ukpga/2023/1/section/11/enacted
+    - title: Finance Act 2025 s. 5(2) (tax year 2028-29)
+      href: https://www.legislation.gov.uk/ukpga/2025/8/section/5/enacted
+    - title: Finance Act 2025 s. 6(2) (tax year 2029-30 and subsequent tax years)
+      href: https://www.legislation.gov.uk/ukpga/2025/8/section/6/enacted
+    - title: "HMRC 480 Appendix 2: appropriate percentages for 2020-21 to 2026-27"
+      href: https://www.gov.uk/guidance/company-car-benefit-the-appropriate-percentage-480-appendix-2
+brackets:
+  # 51 to 54 g/km.
+  - threshold:
+      2020-04-06: 51
+    amount:
+      2020-04-06: 0.15
+      2025-04-06: 0.16
+      2026-04-06: 0.17
+      2027-04-06: 0.18
+      2028-04-06: 0.19
+      2029-04-06: 0.20
+  # 55 to 59 g/km.
+  - threshold:
+      2020-04-06: 55
+    amount:
+      2020-04-06: 0.16
+      2025-04-06: 0.17
+      2026-04-06: 0.18
+      2027-04-06: 0.19
+      2028-04-06: 0.20
+      2029-04-06: 0.21
+  # 60 to 64 g/km.
+  - threshold:
+      2020-04-06: 60
+    amount:
+      2020-04-06: 0.17
+      2025-04-06: 0.18
+      2026-04-06: 0.19
+      2027-04-06: 0.20
+      2028-04-06: 0.21
+      2029-04-06: 0.22
+  # 65 to 69 g/km.
+  - threshold:
+      2020-04-06: 65
+    amount:
+      2020-04-06: 0.18
+      2025-04-06: 0.19
+      2026-04-06: 0.20
+      2027-04-06: 0.21
+      2028-04-06: 0.22
+      2029-04-06: 0.23
+  # 70 to 74 g/km. In 2027-28 Finance Act 2023 s. 11(7) keeps it at 21%,
+  # level with 65-69 g/km and with the 75 g/km rate.
+  - threshold:
+      2020-04-06: 70
+    amount:
+      2020-04-06: 0.19
+      2025-04-06: 0.20
+      2026-04-06: 0.21
+      2027-04-06: 0.21
+      2028-04-06: 0.22
+      2029-04-06: 0.23
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/diesel_supplement.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/diesel_supplement.yaml
new file mode 100644
index 0000000000..04bf928a30
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/diesel_supplement.yaml
@@ -0,0 +1,12 @@
+description: Percentage points added to the appropriate percentage of a company car propelled solely by diesel that does not meet the Euro 6d (RDE2) emissions standard, up to the maximum appropriate percentage.
+values:
+  2020-04-06: 0.04
+metadata:
+  unit: /1
+  period: year
+  label: Company car diesel supplement
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 141
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/141
+    - title: Finance Act 2018 s. 9(3)(b) (4 percentage points from 2018-19)
+      href: https://www.legislation.gov.uk/ukpga/2018/3/section/9/enacted
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/electric_range.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/electric_range.yaml
new file mode 100644
index 0000000000..8958993a9b
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/electric_range.yaml
@@ -0,0 +1,81 @@
+description: Appropriate percentage for a company car with a CO2 emissions figure of 1 to 50 g/km, by its electric range figure in miles (the distance it can be driven in electric mode without recharging), rounded up to a whole number.
+# Finance Act 2025 s. 5 replaces the electric range bands with one rate for
+# 1 to 50 g/km from 2028-29 (18%, then 19% from 2029-30 under s. 6), so
+# every bracket has the same amount from then. s. 5(10) and (11) omit the
+# electric range figure from s. 139 from 2028-29.
+# For 2020-21 and 2021-22 these are the rates for cars first registered
+# before 6 April 2020; registered_from_6_april_2020 holds the s. 139A rates.
+# The tax year 2030-31 keeps 2029-30's 19%. Budget 2026 announced 20%; the
+# company_car_tax_rise_2030 scenario applies it.
+metadata:
+  type: single_amount
+  threshold_unit: mile
+  amount_unit: /1
+  period: year
+  label: Company car appropriate percentage by electric range
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(1) and (2)(b)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
+    - title: Finance (No. 2) Act 2017 s. 2(2) (tax years 2020-21 to 2024-25)
+      href: https://www.legislation.gov.uk/ukpga/2017/32/section/2/enacted
+    - title: Finance Act 2020 s. 8(4)(a) (electric range figure rounded up, from 2020-21)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/8/enacted
+    - title: Finance Act 2023 s. 11 (tax years 2025-26, 2026-27 and 2027-28)
+      href: https://www.legislation.gov.uk/ukpga/2023/1/section/11/enacted
+    - title: Finance Act 2025 s. 5(2) (tax year 2028-29)
+      href: https://www.legislation.gov.uk/ukpga/2025/8/section/5/enacted
+    - title: Finance Act 2025 s. 6(2) (tax year 2029-30 and subsequent tax years)
+      href: https://www.legislation.gov.uk/ukpga/2025/8/section/6/enacted
+    - title: "HMRC 480 Appendix 2: appropriate percentages for 2020-21 to 2026-27"
+      href: https://www.gov.uk/guidance/company-car-benefit-the-appropriate-percentage-480-appendix-2
+brackets:
+  # Electric range figure of less than 30 miles.
+  - threshold:
+      2020-04-06: 0
+    amount:
+      2020-04-06: 0.14
+      2025-04-06: 0.15
+      2026-04-06: 0.16
+      2027-04-06: 0.17
+      2028-04-06: 0.18
+      2029-04-06: 0.19
+  # 30 to 39 miles.
+  - threshold:
+      2020-04-06: 30
+    amount:
+      2020-04-06: 0.12
+      2025-04-06: 0.13
+      2026-04-06: 0.14
+      2027-04-06: 0.15
+      2028-04-06: 0.18
+      2029-04-06: 0.19
+  # 40 to 69 miles.
+  - threshold:
+      2020-04-06: 40
+    amount:
+      2020-04-06: 0.08
+      2025-04-06: 0.09
+      2026-04-06: 0.10
+      2027-04-06: 0.11
+      2028-04-06: 0.18
+      2029-04-06: 0.19
+  # 70 to 129 miles.
+  - threshold:
+      2020-04-06: 70
+    amount:
+      2020-04-06: 0.05
+      2025-04-06: 0.06
+      2026-04-06: 0.07
+      2027-04-06: 0.08
+      2028-04-06: 0.18
+      2029-04-06: 0.19
+  # 130 miles or more.
+  - threshold:
+      2020-04-06: 130
+    amount:
+      2020-04-06: 0.02
+      2025-04-06: 0.03
+      2026-04-06: 0.04
+      2027-04-06: 0.05
+      2028-04-06: 0.18
+      2029-04-06: 0.19
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/electric_range_co2_limit.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/electric_range_co2_limit.yaml
new file mode 100644
index 0000000000..88ed3e0c70
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/electric_range_co2_limit.yaml
@@ -0,0 +1,12 @@
+description: Highest CO2 emissions figure, rounded down to a whole number, at which a company car's appropriate percentage is the rate for 1 to 50 g/km, set by its electric range to 2027-28 and a single rate from 2028-29.
+values:
+  2020-04-06: 50
+metadata:
+  unit: g/km
+  period: year
+  label: Company car CO2 limit for the 1 to 50 g/km band
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(1)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
+    - title: Finance (No. 2) Act 2017 s. 2(2)
+      href: https://www.legislation.gov.uk/ukpga/2017/32/section/2/enacted
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/README.md b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/README.md
new file mode 100644
index 0000000000..e8e7b6d294
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/README.md
@@ -0,0 +1 @@
+# Cars emitting 75 g/km or more
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/base_rate.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/base_rate.yaml
new file mode 100644
index 0000000000..aee4bc3084
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/base_rate.yaml
@@ -0,0 +1,37 @@
+description: Appropriate percentage for a company car with a CO2 emissions figure at the graduated threshold of 75 g/km, before the rise for each step of emissions above it.
+# For 2020-21 and 2021-22 this is the rate for cars first registered before
+# 6 April 2020; registered_from_6_april_2020 holds the s. 139A rate.
+# The tax year 2030-31 keeps 2029-30's 23%. Budget 2026 announced 24%; the
+# company_car_tax_rise_2030 scenario applies it.
+values:
+  2020-04-06:
+    value: 0.2
+    metadata:
+      reference:
+        - title: Finance (No. 2) Act 2017 s. 2(2), substituting ITEPA 2003 s. 139(3)(a)
+          href: https://www.legislation.gov.uk/ukpga/2017/32/section/2/enacted
+  2025-04-06:
+    value: 0.21
+    metadata:
+      reference:
+        - title: Finance Act 2023 s. 11(3) and (4) (tax year 2025-26 and subsequent tax years)
+          href: https://www.legislation.gov.uk/ukpga/2023/1/section/11/enacted
+  2028-04-06:
+    value: 0.22
+    metadata:
+      reference:
+        - title: Finance Act 2025 s. 5(3)(a) and (9) (tax year 2028-29)
+          href: https://www.legislation.gov.uk/ukpga/2025/8/section/5/enacted
+  2029-04-06:
+    value: 0.23
+    metadata:
+      reference:
+        - title: Finance Act 2025 s. 6(3)(a) and (9) (tax year 2029-30 and subsequent tax years)
+          href: https://www.legislation.gov.uk/ukpga/2025/8/section/6/enacted
+metadata:
+  unit: /1
+  period: year
+  label: Company car graduated appropriate percentage base rate
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(3)(a)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/increment.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/increment.yaml
new file mode 100644
index 0000000000..b998a32305
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/increment.yaml
@@ -0,0 +1,10 @@
+description: Rise in a company car's appropriate percentage for each full step of CO2 emissions above the graduated threshold.
+values:
+  2020-04-06: 0.01
+metadata:
+  unit: /1
+  period: year
+  label: Company car graduated appropriate percentage increment
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(3)(a)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/step.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/step.yaml
new file mode 100644
index 0000000000..be1c636caa
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/step.yaml
@@ -0,0 +1,10 @@
+description: Width of each step of CO2 emissions above the graduated threshold that raises a company car's appropriate percentage; the emissions figure is rounded down to a multiple of it.
+values:
+  2020-04-06: 5
+metadata:
+  unit: g/km
+  period: year
+  label: Company car graduated appropriate percentage step
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(3)(a) and (4)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/threshold.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/threshold.yaml
new file mode 100644
index 0000000000..c81d52b811
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/graduated/threshold.yaml
@@ -0,0 +1,12 @@
+description: CO2 emissions figure from which a company car's appropriate percentage is the base rate plus a rise for each step of emissions above it, rather than a rate from the table for lower emissions.
+values:
+  2020-04-06: 75
+metadata:
+  unit: g/km
+  period: year
+  label: Company car graduated appropriate percentage threshold
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(1) and (3)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
+    - title: Finance (No. 2) Act 2017 s. 2(2)
+      href: https://www.legislation.gov.uk/ukpga/2017/32/section/2/enacted
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/maximum.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/maximum.yaml
new file mode 100644
index 0000000000..506217b3c5
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/maximum.yaml
@@ -0,0 +1,45 @@
+description: Maximum appropriate percentage for a company car, which caps both the graduated rate and a diesel car's rate after its supplement.
+# Two provisions set this figure: s. 139(3)(b) for the graduated rate and
+# s. 141(2) step 3(b) for a diesel car. They have moved together, so the
+# model holds one figure. For s. 141, legislation.gov.uk prints 35%: Finance
+# Act 2015 s. 9 substituted 37% for the tax year 2015-16 only, when Finance
+# Act 2014 s. 24(11) was to omit s. 141 from 2016-17, and Finance Act 2016
+# s. 10 then kept s. 141 without restating the cap. Finance Act 2025 s. 5(6)
+# substitutes 38% "for '37%'" in step 3, and HMRC 480 (paragraph 12.29, note
+# 2) applies the 37% maximum to diesel cars from 2015-16, so the model uses
+# 37% for both to 2027-28.
+# The tax year 2030-31 keeps 2029-30's 39%. Budget 2026 announced 40%, for
+# s. 139(3)(b) and s. 141 alike; the company_car_tax_rise_2030 scenario
+# applies it.
+values:
+  2020-04-06:
+    value: 0.37
+    metadata:
+      reference:
+        - title: Finance (No. 2) Act 2017 s. 2(2), substituting ITEPA 2003 s. 139(3)(b)
+          href: https://www.legislation.gov.uk/ukpga/2017/32/section/2/enacted
+        - title: Finance Act 2015 s. 9 (ITEPA 2003 s. 141(2) step 3, 37% for 2015-16)
+          href: https://www.legislation.gov.uk/ukpga/2015/11/section/9/enacted
+        - title: "HMRC 480 Chapter 12, paragraph 12.29, note 2: overall maximum of 37% from 2015-16"
+          href: https://www.gov.uk/guidance/how-to-work-out-the-benefit-of-a-company-car-480-chapter-12
+  2028-04-06:
+    value: 0.38
+    metadata:
+      reference:
+        - title: Finance Act 2025 s. 5(3)(b), (6) and (9) (tax year 2028-29)
+          href: https://www.legislation.gov.uk/ukpga/2025/8/section/5/enacted
+  2029-04-06:
+    value: 0.39
+    metadata:
+      reference:
+        - title: Finance Act 2025 s. 6(3)(b), (6) and (9) (tax year 2029-30 and subsequent tax years)
+          href: https://www.legislation.gov.uk/ukpga/2025/8/section/6/enacted
+metadata:
+  unit: /1
+  period: year
+  label: Company car maximum appropriate percentage
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(3)(b)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 141(2), step 3(b)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/141
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/README.md b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/README.md
new file mode 100644
index 0000000000..ac269a7dc9
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/README.md
@@ -0,0 +1 @@
+# Cars first registered on or after 6 April 2020
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/co2_band.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/co2_band.yaml
new file mode 100644
index 0000000000..262c37cd43
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/co2_band.yaml
@@ -0,0 +1,43 @@
+description: Appropriate percentage under ITEPA 2003 s. 139A for a company car first registered on or after 6 April 2020 with a CO2 emissions figure of 51 to 74 g/km, while s. 139A is in effect.
+metadata:
+  type: single_amount
+  threshold_unit: g/km
+  amount_unit: /1
+  period: year
+  label: Appropriate percentage by CO2 emissions, cars first registered from 6 April 2020
+  reference:
+    - title: Finance Act 2020 s. 9(3) (tax year 2020-21)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted
+    - title: Finance Act 2020 s. 10(3) (tax year 2021-22)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/10/enacted
+brackets:
+  # 51 to 54 g/km.
+  - threshold:
+      2020-04-06: 51
+    amount:
+      2020-04-06: 0.13
+      2021-04-06: 0.14
+  # 55 to 59 g/km.
+  - threshold:
+      2020-04-06: 55
+    amount:
+      2020-04-06: 0.14
+      2021-04-06: 0.15
+  # 60 to 64 g/km.
+  - threshold:
+      2020-04-06: 60
+    amount:
+      2020-04-06: 0.15
+      2021-04-06: 0.16
+  # 65 to 69 g/km.
+  - threshold:
+      2020-04-06: 65
+    amount:
+      2020-04-06: 0.16
+      2021-04-06: 0.17
+  # 70 to 74 g/km.
+  - threshold:
+      2020-04-06: 70
+    amount:
+      2020-04-06: 0.17
+      2021-04-06: 0.18
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/electric_range.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/electric_range.yaml
new file mode 100644
index 0000000000..77b922480f
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/electric_range.yaml
@@ -0,0 +1,43 @@
+description: Appropriate percentage under ITEPA 2003 s. 139A for a company car first registered on or after 6 April 2020 with a CO2 emissions figure of 1 to 50 g/km, by its electric range figure in miles, while s. 139A is in effect.
+metadata:
+  type: single_amount
+  threshold_unit: mile
+  amount_unit: /1
+  period: year
+  label: Appropriate percentage by electric range, cars first registered from 6 April 2020
+  reference:
+    - title: Finance Act 2020 s. 9(3) (tax year 2020-21)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted
+    - title: Finance Act 2020 s. 10(3) (tax year 2021-22)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/10/enacted
+brackets:
+  # Electric range figure of less than 30 miles.
+  - threshold:
+      2020-04-06: 0
+    amount:
+      2020-04-06: 0.12
+      2021-04-06: 0.13
+  # 30 to 39 miles.
+  - threshold:
+      2020-04-06: 30
+    amount:
+      2020-04-06: 0.1
+      2021-04-06: 0.11
+  # 40 to 69 miles.
+  - threshold:
+      2020-04-06: 40
+    amount:
+      2020-04-06: 0.06
+      2021-04-06: 0.07
+  # 70 to 129 miles.
+  - threshold:
+      2020-04-06: 70
+    amount:
+      2020-04-06: 0.03
+      2021-04-06: 0.04
+  # 130 miles or more.
+  - threshold:
+      2020-04-06: 130
+    amount:
+      2020-04-06: 0
+      2021-04-06: 0.01
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/graduated_base_rate.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/graduated_base_rate.yaml
new file mode 100644
index 0000000000..3b3caacd81
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/graduated_base_rate.yaml
@@ -0,0 +1,23 @@
+description: Appropriate percentage under ITEPA 2003 s. 139A for a company car first registered on or after 6 April 2020 with a CO2 emissions figure of 75 g/km, before the rise for each step of emissions above it, while s. 139A is in effect. The maximum appropriate percentage is unchanged.
+values:
+  2020-04-06:
+    value: 0.18
+    metadata:
+      reference:
+        - title: Finance Act 2020 s. 9(3) (tax year 2020-21)
+          href: https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted
+  2021-04-06:
+    value: 0.19
+    metadata:
+      reference:
+        - title: Finance Act 2020 s. 10(3) (tax year 2021-22)
+          href: https://www.legislation.gov.uk/ukpga/2020/14/section/10/enacted
+metadata:
+  unit: /1
+  period: year
+  label: Graduated appropriate percentage base rate, cars first registered from 6 April 2020
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139A(b), inserted for 2020-21 by Finance Act 2020 s. 9(3)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139A(b), inserted for 2021-22 by Finance Act 2020 s. 10(3)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/10/enacted
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/in_effect.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/in_effect.yaml
new file mode 100644
index 0000000000..c9df564da0
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/registered_from_6_april_2020/in_effect.yaml
@@ -0,0 +1,16 @@
+description: Whether ITEPA 2003 s. 139A gives a company car first registered on or after 6 April 2020 its own, lower appropriate percentages. Finance Act 2020 inserted s. 139A for 2020-21 (s. 9(3)) and again for 2021-22 (s. 10(3)); from 2022-23 every car takes the s. 139 rates.
+values:
+  0000-01-01: false
+  2020-04-06: true
+  2022-04-06: false
+metadata:
+  unit: bool
+  period: year
+  label: Separate appropriate percentages for cars first registered from 6 April 2020
+  reference:
+    - title: Finance Act 2020 s. 9(3) (tax year 2020-21)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted
+    - title: Finance Act 2020 s. 10(3) (tax year 2021-22)
+      href: https://www.legislation.gov.uk/ukpga/2020/14/section/10/enacted
+    - title: "HMRC 480 Appendix 2: NEDC and WLTP columns for 2020-21 and 2021-22"
+      href: https://www.gov.uk/guidance/company-car-benefit-the-appropriate-percentage-480-appendix-2
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/zero_emission.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/zero_emission.yaml
new file mode 100644
index 0000000000..b63c4517ce
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/appropriate_percentage/zero_emission.yaml
@@ -0,0 +1,62 @@
+description: Appropriate percentage for a company car with a CO2 emissions figure of 0, the share of the car's price taxed each year as its benefit.
+# The tax year 2030-31 keeps 2029-30's 9%. Budget 2026 announced 10% for
+# 2030-31, to be legislated in Finance Bill 2026-27; the
+# company_car_tax_rise_2030 scenario applies it.
+values:
+  2020-04-06:
+    value: 0
+    metadata:
+      reference:
+        - title: Finance Act 2020 s. 9(2)(a) (tax year 2020-21)
+          href: https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted
+  2021-04-06:
+    value: 0.01
+    metadata:
+      reference:
+        - title: Finance Act 2020 s. 10(2)(a) (tax year 2021-22)
+          href: https://www.legislation.gov.uk/ukpga/2020/14/section/10/enacted
+  2022-04-06:
+    value: 0.02
+    metadata:
+      reference:
+        - title: Finance (No. 2) Act 2017 s. 2(2), substituting ITEPA 2003 s. 139(1)
+          href: https://www.legislation.gov.uk/ukpga/2017/32/section/2/enacted
+  2025-04-06:
+    value: 0.03
+    metadata:
+      reference:
+        - title: Finance Act 2023 s. 11(1) and (2) (tax year 2025-26)
+          href: https://www.legislation.gov.uk/ukpga/2023/1/section/11/enacted
+  2026-04-06:
+    value: 0.04
+    metadata:
+      reference:
+        - title: Finance Act 2023 s. 11(5) and (6) (tax year 2026-27)
+          href: https://www.legislation.gov.uk/ukpga/2023/1/section/11/enacted
+  2027-04-06:
+    value: 0.05
+    metadata:
+      reference:
+        - title: Finance Act 2023 s. 11(7) and (8) (tax year 2027-28)
+          href: https://www.legislation.gov.uk/ukpga/2023/1/section/11/enacted
+  2028-04-06:
+    value: 0.07
+    metadata:
+      reference:
+        - title: Finance Act 2025 s. 5(2) and (9) (tax year 2028-29)
+          href: https://www.legislation.gov.uk/ukpga/2025/8/section/5/enacted
+  2029-04-06:
+    value: 0.09
+    metadata:
+      reference:
+        - title: Finance Act 2025 s. 6(2) and (9) (tax year 2029-30 and subsequent tax years)
+          href: https://www.legislation.gov.uk/ukpga/2025/8/section/6/enacted
+metadata:
+  unit: /1
+  period: year
+  label: Zero-emission company car appropriate percentage
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 139(1)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/139
+    - title: "HMRC 480 Appendix 2: appropriate percentages for 2020-21 to 2026-27"
+      href: https://www.gov.uk/guidance/company-car-benefit-the-appropriate-percentage-480-appendix-2
diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/capital_contribution_cap.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/capital_contribution_cap.yaml
new file mode 100644
index 0000000000..5f531821a8
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/income_tax/benefits_in_kind/company_car/capital_contribution_cap.yaml
@@ -0,0 +1,10 @@
+description: Maximum deduction from a company car's price for capital sums the employee has contributed, in the year and earlier years, to the car and its accessories.
+values:
+  2003-04-06: 5_000
+metadata:
+  unit: currency-GBP
+  period: year
+  label: Company car capital contribution cap
+  reference:
+    - title: Income Tax (Earnings and Pensions) Act 2003 s. 132(3)(b)
+      href: https://www.legislation.gov.uk/ukpga/2003/1/section/132
diff --git a/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/README.md b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/README.md
new file mode 100644
index 0000000000..30f1be9de4
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/README.md
@@ -0,0 +1 @@
+# Class 1A
diff --git a/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/README.md b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/README.md
new file mode 100644
index 0000000000..bc41cad93b
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/README.md
@@ -0,0 +1 @@
+# Class 1A percentage for 2022-23
diff --git a/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/in_effect.yaml b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/in_effect.yaml
new file mode 100644
index 0000000000..c2f3aa3403
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/in_effect.yaml
@@ -0,0 +1,12 @@
+description: Whether the Class 1A percentage is the fixed rate the Health and Social Care Levy (Repeal) Act 2022 sets for 2022-23, rather than the secondary Class 1 percentage it equals in other tax years.
+values:
+  0000-01-01: false
+  2022-04-06: true
+  2023-04-06: false
+metadata:
+  unit: bool
+  period: year
+  label: Fixed Class 1A percentage for 2022-23
+  reference:
+    - title: Health and Social Care Levy (Repeal) Act 2022 Schedule paragraph 1
+      href: https://www.legislation.gov.uk/ukpga/2022/43/schedule/paragraph/1/enacted
diff --git a/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/rate.yaml b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/rate.yaml
new file mode 100644
index 0000000000..113eb1cda8
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/national_insurance/class_1a/percentage_2022_23/rate.yaml
@@ -0,0 +1,10 @@
+description: Class 1A percentage for 2022-23, which applies to the whole year's benefits in kind although the secondary Class 1 percentage fell from 15.05% to 13.8% on 6 November 2022.
+values:
+  2022-04-06: 0.1453
+metadata:
+  unit: /1
+  period: year
+  label: Class 1A percentage for 2022-23
+  reference:
+    - title: Health and Social Care Levy (Repeal) Act 2022 Schedule paragraph 1(2)
+      href: https://www.legislation.gov.uk/ukpga/2022/43/schedule/paragraph/1/enacted
diff --git a/policyengine_uk/programs.yaml b/policyengine_uk/programs.yaml
index 734a227b56..ed22040b61 100644
--- a/policyengine_uk/programs.yaml
+++ b/policyengine_uk/programs.yaml
@@ -50,7 +50,7 @@ programs:
     variable: income_tax
     parameter_prefix: gov.hmrc.income_tax
     verified_start_year: 2019
-    notes: Includes Scottish rates via devolved tax bands, the high income child benefit charge and, from 2025-26, the winter fuel payment charge
+    notes: Includes Scottish rates via devolved tax bands, the high income child benefit charge, from 2025-26 the winter fuel payment charge, and from 2020-21 the company car and car fuel benefits in kind (no other benefits in kind, and no vans)
 
   - id: national_insurance
     name: National Insurance
@@ -62,7 +62,7 @@ programs:
     variable: national_insurance
     parameter_prefix: gov.hmrc.national_insurance
     verified_start_year: 2019
-    notes: Classes 1, 2, 3, and 4
+    notes: Classes 1, 2, 3, and 4, and Class 1A on the company car and car fuel benefits
 
   - id: capital_gains_tax
     name: Capital gains tax
diff --git a/policyengine_uk/scenarios/__init__.py b/policyengine_uk/scenarios/__init__.py
index 4be5973b03..e206fa2af7 100644
--- a/policyengine_uk/scenarios/__init__.py
+++ b/policyengine_uk/scenarios/__init__.py
@@ -1,4 +1,5 @@
 from .abolish_benefit_cap import abolish_benefit_cap
+from .company_car_tax_rise_2030 import company_car_tax_rise_2030
 from .no_economic_assumptions import no_economic_assumptions
 from .pip_reform import reform_pip_phase_in
 from .reindex_benefit_cap import reindex_benefit_cap
diff --git a/policyengine_uk/scenarios/company_car_tax_rise_2030.py b/policyengine_uk/scenarios/company_car_tax_rise_2030.py
new file mode 100644
index 0000000000..cc1679e3d0
--- /dev/null
+++ b/policyengine_uk/scenarios/company_car_tax_rise_2030.py
@@ -0,0 +1,44 @@
+"""Budget 2026's company car tax rates for 2030-31.
+
+Budget 2026 sets every company car appropriate percentage for 2030-31 one
+point above 2029-30's, zero-emission cars included, and raises the maximum
+from 39% to 40% (ITEPA 2003 s. 139(1), (3)(a) and (3)(b), and the diesel
+cap in s. 141(2) step 3). Finance Bill 2026-27 is to legislate it, so the
+baseline keeps 2029-30's rates for 2030-31 and this scenario applies the
+rise from 6 April 2030. Table 6.1 of Budget 2026 (row 86) costs it at
++£310m in 2030-31 and +£345m in 2031-32.
+
+Sources: Budget 2026, overview of tax legislation and rates, paragraph 1.25;
+HMRC, "Taxation of company cars: the appropriate percentage for tax years
+2030 to 2031 and 2031 to 2032" (28 October 2026).
+"""
+
+from policyengine_uk.model_api import Scenario
+
+APPROPRIATE_PERCENTAGE = (
+    "gov.hmrc.income_tax.benefits_in_kind.company_car.appropriate_percentage"
+)
+FROM_2030_31 = "2030-04-06.2100-12-31"
+
+# Each rate is 2029-30's (Finance Act 2025 s. 6) plus one point.
+COMPANY_CAR_TAX_RISE_2030 = {
+    f"{APPROPRIATE_PERCENTAGE}.zero_emission": {FROM_2030_31: 0.10},
+    # 1 to 50 g/km, one rate whatever the electric range.
+    **{
+        f"{APPROPRIATE_PERCENTAGE}.electric_range[{bracket}].amount": {
+            FROM_2030_31: 0.20
+        }
+        for bracket in range(5)
+    },
+    # 51-54, 55-59, 60-64, 65-69 and 70-74 g/km.
+    f"{APPROPRIATE_PERCENTAGE}.co2_band[0].amount": {FROM_2030_31: 0.21},
+    f"{APPROPRIATE_PERCENTAGE}.co2_band[1].amount": {FROM_2030_31: 0.22},
+    f"{APPROPRIATE_PERCENTAGE}.co2_band[2].amount": {FROM_2030_31: 0.23},
+    f"{APPROPRIATE_PERCENTAGE}.co2_band[3].amount": {FROM_2030_31: 0.24},
+    f"{APPROPRIATE_PERCENTAGE}.co2_band[4].amount": {FROM_2030_31: 0.24},
+    # 75 g/km, and one point more for each 5 g/km above it.
+    f"{APPROPRIATE_PERCENTAGE}.graduated.base_rate": {FROM_2030_31: 0.24},
+    f"{APPROPRIATE_PERCENTAGE}.maximum": {FROM_2030_31: 0.40},
+}
+
+company_car_tax_rise_2030 = Scenario(parameter_changes=COMPANY_CAR_TAX_RISE_2030)
diff --git a/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/benefits_in_kind_interactions.yaml b/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/benefits_in_kind_interactions.yaml
new file mode 100644
index 0000000000..8b9d782e1c
--- /dev/null
+++ b/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/benefits_in_kind_interactions.yaml
@@ -0,0 +1,239 @@
+# Where the company car benefit goes. A person paid £20,000 in 2026-27 has
+# a zero-emission company car with a list price of £75,000, so a benefit of
+# £75,000 x 4% = £3,000. The benefit is employment income for income tax
+# (ITEPA 2003 s. 120) and so counts in adjusted net income. It is not
+# earnings for employee Class 1 NICs, nor for Universal Credit (UC
+# Regulations 2013 reg. 55(2)(a)), Housing Benefit (HB Regulations 2006
+# reg. 35(2)(a)) or Council Tax Reduction. Those earnings tests do deduct the
+# income tax on it, which is tax paid in respect of the employment (UC reg.
+# 55(5)(b)); PAYE collects it from the person's pay.
+
+- name: Without the company car
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 20_000
+  output:
+    taxable_employment_income: 20_000
+    adjusted_net_income: 20_000
+    # (£20,000 - £12,570) x 20% = £1,486.
+    income_tax: 1_486
+    # (£20,000 - £12,570) x 8% = £594.40.
+    ni_class_1_employee: 594.4
+    uc_income_tax_on_earnings: 1_486
+    # £20,000 - £1,486 - £594.40 = £17,919.60.
+    uc_individual_earned_income_before_mif: 17_919.6
+    housing_benefit_net_earnings: 17_919.6
+    council_tax_reduction_net_earnings: 17_919.6
+    # (£20,000 - £5,000) x 15% = £2,250.
+    ni_employer: 2_250
+
+- name: With the company car
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 20_000
+    company_car_list_price: 75_000
+    company_car_co2_emissions: 0
+    company_car_fuel_type: ELECTRIC
+  output:
+    company_car_benefit: 3_000
+    # Income tax and adjusted net income include the benefit.
+    taxable_employment_income: 23_000
+    adjusted_net_income: 23_000
+    # (£23,000 - £12,570) x 20% = £2,086.
+    income_tax: 2_086
+    # Pay, statutory pay and Class 1 earnings leave the benefit out.
+    employment_income: 20_000
+    employment_benefits: 0
+    ni_class_1_income: 20_000
+    ni_class_1_employee: 594.4
+    # The earnings tests leave the benefit out and deduct the income tax on
+    # it: £20,000 - £2,086 - £594.40 = £17,319.60.
+    uc_income_tax_on_earnings: 2_086
+    uc_individual_earned_income_before_mif: 17_319.6
+    housing_benefit_net_earnings: 17_319.6
+    council_tax_reduction_net_earnings: 17_319.6
+    # Class 1A of £3,000 x 15% = £450 on top of secondary Class 1.
+    ni_class_1a: 450
+    ni_employer: 2_700
+
+- name: The benefit reaches the personal allowance taper
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 100_000
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    # 120 g/km is 30%: a £12,000 benefit takes adjusted net income to
+    # £112,000, so the allowance falls by £12,000 / 2 to £6,570
+    # (Income Tax Act 2007 s. 35).
+    adjusted_net_income: 112_000
+    personal_allowance: 6_570
+
+- name: The benefit counts towards the High Income Child Benefit Charge
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      parent:
+        age: 40
+        employment_income: 58_000
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 120
+      child:
+        age: 5
+    benunits:
+      benunit:
+        members: [parent, child]
+        would_claim_child_benefit: true
+    households:
+      household:
+        members: [parent, child]
+  output:
+    # Adjusted net income of £70,000 is above the £60,000 to £80,000 taper
+    # midpoint, so the charge is half the Child Benefit
+    # (Income Tax (Earnings and Pensions) Act 2003 s. 681C).
+    adjusted_net_income: [70_000, 0]
+    # Child Benefit of £27.05 a week for 52 weeks is £1,406.60, rounded
+    # down to £1,406; half of it is £703 (s. 681C(3)).
+    CB_HITC: [703, 0]
+
+- name: Student loan repayments leave the benefit out
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 30
+    employment_income: 40_000
+    student_loan_plan: PLAN_2
+    company_car_list_price: 30_000
+    company_car_co2_emissions: 120
+  output:
+    # A £9,000 benefit (30% of £30,000) is in net income, but not in the
+    # income repayments are due on: Self Assessment leaves out Chapter 6 car
+    # benefits (SI 2009/470 reg. 29(4)(e)) and PAYE deducts repayments from
+    # Class 1 earnings (reg. 41). 9% of (£40,000 - £29,385) = £955.35.
+    net_income: 49_000
+    student_loan_repayment: 955.35
+
+- name: Student loans leave out only the part of the benefit that deductions leave in income
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 30
+    employment_income: 10_000
+    employment_expenses: 15_000
+    private_pension_income: 30_000
+    student_loan_plan: PLAN_2
+    company_car_list_price: 30_000
+    company_car_co2_emissions: 120
+  output:
+    # Allowable expenses of £15,000 come off pay and the £9,000 benefit
+    # together (ITEPA 2003 s. 11): taxable employment income is £4,000, and
+    # would be nil without the car. So net income of £34,000 holds £4,000
+    # of the benefit, and repayment income is £30,000, the pension:
+    # 9% of (£30,000 - £29,385) = £55.35.
+    taxable_employment_income: 4_000
+    net_income: 34_000
+    student_loan_repayment: 55.35
+
+- name: The pension relief limit counts the benefit as relevant UK earnings
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 10_000
+    personal_pension_contributions: 14_000
+    company_car_list_price: 20_000
+    company_car_co2_emissions: 120
+  output:
+    # Taxable benefits in kind are employment income chargeable to tax, so
+    # relevant UK earnings (Finance Act 2004 s. 189(2)(a); HMRC PTM044100):
+    # £10,000 + £6,000 = £16,000 is above the £14,000 contributed, so all of
+    # it is relieved. Without the car the limit would be £10,000.
+    pension_contributions_relief: 14_000
+
+- name: A Scottish taxpayer pays Scottish rates on the benefit
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      person:
+        age: 40
+        employment_income: 35_000
+        company_car_list_price: 75_000
+        company_car_co2_emissions: 0
+        company_car_fuel_type: ELECTRIC
+    benunits:
+      benunit:
+        members: [person]
+    households:
+      household:
+        members: [person]
+        region: SCOTLAND
+  output:
+    # Taxable income of £35,000 + £3,000 - £12,570 = £25,430, all within
+    # the intermediate band (21%) above £16,956: 19% of £3,967, 20% of
+    # £12,989 and 21% of £8,474 = £5,131.07, of which 21% of the £3,000
+    # benefit is £630.
+    income_tax: 5_131.07
+
+- name: The benefit counts towards the £100,000 limits of Tax-Free Childcare and the extended entitlement
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    age: 40
+    employment_income: 95_000
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    # Adjusted net income of £95,000 + £12,000 is above £100,000 (SI
+    # 2015/448 reg. 15; SI 2022/1134 regs. 14(3)(c)(i) and 15(3)(b)(i)).
+    adjusted_net_income: 107_000
+    tax_free_childcare_meets_income_requirements: false
+    extended_childcare_entitlement_meets_income_requirements: false
+
+- name: Earnings tests with other income, without the company car
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 20_000
+    private_pension_income: 20_000
+  output:
+    # (£40,000 - £12,570) x 20% = £5,486.
+    income_tax: 5_486
+    # UC takes earnings as the lowest slice: (£20,000 - £12,570) x 20%.
+    uc_income_tax_on_earnings: 1_486
+    uc_individual_earned_income_before_mif: 17_919.6
+    # HB and CTR take earnings' share of the tax: £5,486 x 20/40 = £2,743;
+    # £20,000 - £2,743 - £594.40 = £16,662.60.
+    housing_benefit_net_earnings: 16_662.6
+    council_tax_reduction_net_earnings: 16_662.6
+
+- name: Earnings tests with other income, with the company car
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 20_000
+    private_pension_income: 20_000
+    company_car_list_price: 75_000
+    company_car_co2_emissions: 0
+    company_car_fuel_type: ELECTRIC
+  output:
+    # The £3,000 benefit adds £600 of tax: (£43,000 - £12,570) x 20%.
+    income_tax: 6_086
+    # UC deducts all £600 from earnings, as the benefit is in the lowest
+    # slice with pay.
+    uc_income_tax_on_earnings: 2_086
+    uc_individual_earned_income_before_mif: 17_319.6
+    # HB and CTR count the benefit with pay in earnings' share of the tax,
+    # though not in the earnings: £6,086 x 23/43 = £3,255.30, so
+    # £20,000 - £3,255.30 - £594.40 = £16,150.30.
+    housing_benefit_net_earnings: 16_150.29
+    council_tax_reduction_net_earnings: 16_150.29
diff --git a/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/car_fuel_benefit.yaml b/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/car_fuel_benefit.yaml
new file mode 100644
index 0000000000..7c919c6207
--- /dev/null
+++ b/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/car_fuel_benefit.yaml
@@ -0,0 +1,131 @@
+# The car fuel benefit (ITEPA 2003 ss. 149 to 152). HMRC 480 Chapter 13
+# gives the worked example for 2021-22:
+# https://www.gov.uk/guidance/taxable-fuel-provided-for-company-cars-and-vans-480-chapter-13
+
+- name: HMRC 480 paragraph 13.6, a petrol car first registered on or after 6 April 2020, in 2021-22
+  period: 2021
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 30_000
+    company_car_co2_emissions: 160
+    company_car_registered_from_6_april_2020: true
+    company_car_private_fuel_provided: true
+  output:
+    # The appropriate percentage for the car is 36%, and the 2021-22 car
+    # fuel benefit charge is £24,600 x 36% = £8,856.
+    company_car_appropriate_percentage: 0.36
+    car_fuel_benefit: 8_856
+
+- name: Diesel car not meeting RDE2 with private fuel, in 2026-27
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 15_000
+    company_car_co2_emissions: 156
+    company_car_fuel_type: DIESEL_NON_RDE2
+    company_car_private_fuel_provided: true
+  output:
+    # The car's 37% of the £29,200 multiplier (SI 2025/1254): £10,804.
+    car_fuel_benefit: 10_804
+
+- name: 2027-28 uses the multiplier announced at Budget 2026
+  period: 2027
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+    company_car_private_fuel_provided: true
+  output:
+    # 120 g/km is 30% in 2027-28 (HMRC future rates table). OOTLAR
+    # paragraph 2.6 gives a £30,200 multiplier: £30,200 x 30% = £9,060.
+    car_fuel_benefit: 9_060
+
+- name: No fuel benefit when private fuel is made good in full
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    company_car_list_price: 15_000
+    company_car_co2_emissions: 156
+    company_car_private_fuel_provided: false
+  output:
+    # s. 151, condition A.
+    car_fuel_benefit: 0
+
+- name: No fuel benefit for a car that cannot emit CO2
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 0
+    company_car_fuel_type: ELECTRIC
+    company_car_private_fuel_provided: true
+  output:
+    # s. 149(4): energy for such a car is not fuel.
+    car_fuel_benefit: 0
+
+- name: Fuel benefit is reduced for days the car is unavailable
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 15_000
+    company_car_co2_emissions: 156
+    company_car_fuel_type: DIESEL_NON_RDE2
+    company_car_private_fuel_provided: true
+    company_car_availability: 0.5
+  output:
+    # s. 152(1): £10,804 x 0.5 = £5,402.
+    car_fuel_benefit: 5_402
+
+- name: Payments for private use and capital contributions do not reduce the fuel benefit
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 15_000
+    company_car_capital_contributions: 5_000
+    company_car_co2_emissions: 156
+    company_car_fuel_type: DIESEL_NON_RDE2
+    company_car_private_fuel_provided: true
+    company_car_private_use_payments: 10_000
+  output:
+    # HMRC 480 paragraph 13.1: a fuel benefit arises even where these
+    # reduce the car benefit to nil.
+    company_car_benefit: 0
+    car_fuel_benefit: 10_804
+
+- name: No fuel benefit without a company car
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    company_car_co2_emissions: 120
+    company_car_private_fuel_provided: true
+  output:
+    car_fuel_benefit: 0
+
+- name: Fuel benefit for a 1-50 g/km hybrid, in 2026-27
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 32_000
+    company_car_co2_emissions: 40
+    company_car_electric_range: 35
+    company_car_private_fuel_provided: true
+  output:
+    # 30-39 miles is 14% (HMRC 480 Appendix 2, 2026-27): the petrol it
+    # burns is fuel, the electricity is not (s. 149(4)).
+    # £29,200 x 14% = £4,088.
+    car_fuel_benefit: 4_088
+
+- name: Fuel benefit under the s. 139A rates, in 2021-22
+  period: 2021
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 22_000
+    company_car_co2_emissions: 50
+    company_car_electric_range: 65
+    company_car_registered_from_6_april_2020: true
+    company_car_private_fuel_provided: true
+  output:
+    # WLTP, 40-69 miles: 7% (HMRC 480 Appendix 2, 2021-22).
+    # £24,600 x 7% = £1,722.
+    company_car_appropriate_percentage: 0.07
+    car_fuel_benefit: 1_722
diff --git a/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/company_car_benefit.yaml b/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/company_car_benefit.yaml
new file mode 100644
index 0000000000..83901092d5
--- /dev/null
+++ b/policyengine_uk/tests/policy/baseline/gov/hmrc/income_tax/benefits_in_kind/company_car_benefit.yaml
@@ -0,0 +1,398 @@
+# The company car benefit (ITEPA 2003 s. 121). HMRC 480 Appendix 1 (company
+# car benefit examples) gives worked results for 2020-21 in Examples 6 and 7,
+# tested here. Its Examples 3 to 5 are for 2018-19, before the model's first
+# year, so the cases below that reuse their cars are not HMRC's worked
+# results: they value those cars with the rates in HMRC 480 Appendix 2's
+# 2026-27 table, and so test the transcribed rates.
+# https://www.gov.uk/guidance/company-car-benefit-examples-480-appendix-1
+# https://www.gov.uk/guidance/company-car-benefit-the-appropriate-percentage-480-appendix-2
+
+- name: No company car gives no benefit
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    employment_income: 40_000
+  output:
+    has_company_car: false
+    company_car_appropriate_percentage: 0
+    company_car_benefit: 0
+    car_fuel_benefit: 0
+    benefits_in_kind: 0
+    taxable_employment_income: 40_000
+
+- name: HMRC 480 Appendix 1 Example 6, a hybrid first registered before 6 April 2020, in 2020-21
+  period: 2020
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 32_000
+    company_car_co2_emissions: 50
+    company_car_electric_range: 77
+  output:
+    # First registered on 22 March 2020, so the NEDC figures: 1-50 g/km
+    # with an electric range of 70-129 miles is 5%. £32,000 x 5% = £1,600.
+    company_car_appropriate_percentage: 0.05
+    company_car_benefit: 1_600
+
+- name: HMRC 480 Appendix 1 Example 7, a hybrid first registered on 6 April 2020, in 2020-21
+  period: 2020
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 22_000
+    company_car_co2_emissions: 50
+    company_car_electric_range: 65
+    company_car_registered_from_6_april_2020: true
+  output:
+    # WLTP figures, so the s. 139A rates: 40-69 miles is 6%.
+    # £22,000 x 6% = £1,320.
+    company_car_appropriate_percentage: 0.06
+    company_car_benefit: 1_320
+
+- name: The s. 139A rates end after 2021-22
+  period: 2022
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 22_000
+    company_car_co2_emissions: 50
+    company_car_electric_range: 65
+    company_car_registered_from_6_april_2020: true
+  output:
+    # HMRC 480 Appendix 2, 2022-23: 40-69 miles is 8% for NEDC and WLTP
+    # cars alike. £22,000 x 8% = £1,760.
+    company_car_appropriate_percentage: 0.08
+    company_car_benefit: 1_760
+
+- name: Petrol car at 100 g/km (the car in HMRC 480 Appendix 1 Example 5) at 2026-27 rates
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 18_000
+    company_car_co2_emissions: 104
+  output:
+    # 104 rounds down to 100 g/km: 26% (Appendix 2, 2026-27).
+    # £18,000 x 26% = £4,680.
+    company_car_appropriate_percentage: 0.26
+    company_car_benefit: 4_680
+
+- name: Petrol car at the maximum (the car in HMRC 480 Appendix 1 Example 3) at 2026-27 rates
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 15_000
+    company_car_co2_emissions: 173
+  output:
+    # 173 rounds down to 170 g/km: 37% (Appendix 2, 2026-27, 170 and
+    # above). £15,000 x 37% = £5,550.
+    company_car_appropriate_percentage: 0.37
+    company_car_benefit: 5_550
+
+- name: Diesel car not meeting RDE2 takes the 4-point supplement, in 2026-27
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 18_000
+    company_car_co2_emissions: 104
+    company_car_fuel_type: DIESEL_NON_RDE2
+  output:
+    # 26% for 100 g/km plus the 4-point diesel supplement (HMRC 480
+    # paragraph 12.29). £18,000 x 30% = £5,400.
+    company_car_appropriate_percentage: 0.3
+    company_car_benefit: 5_400
+
+- name: Diesel car meeting RDE2 takes no supplement, in 2026-27
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 18_000
+    company_car_co2_emissions: 104
+    company_car_fuel_type: DIESEL_RDE2
+  output:
+    company_car_appropriate_percentage: 0.26
+    company_car_benefit: 4_680
+
+- name: Diesel supplement stops at the maximum (the car in HMRC 480 Appendix 1 Example 4) at 2026-27 rates
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 15_000
+    company_car_co2_emissions: 156
+    company_car_fuel_type: DIESEL_NON_RDE2
+  output:
+    # 156 rounds down to 155 g/km: 37% (Appendix 2, 2026-27). Adding 4
+    # points would pass the 37% maximum (paragraph 12.29, note 2).
+    # £15,000 x 37% = £5,550.
+    company_car_appropriate_percentage: 0.37
+    company_car_benefit: 5_550
+
+- name: 1-50 g/km cars in each electric range band, in 2026-27
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      range_130:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 50
+        company_car_electric_range: 130
+      range_77:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 50
+        company_car_electric_range: 77
+      range_65:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 50
+        company_car_electric_range: 65
+      range_35:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 50
+        company_car_electric_range: 35
+      range_20:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 50
+        company_car_electric_range: 20
+      range_29_point_2:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 50
+        company_car_electric_range: 29.2
+    benunits:
+      benunit:
+        members: [range_130, range_77, range_65, range_35, range_20, range_29_point_2]
+    households:
+      household:
+        members: [range_130, range_77, range_65, range_35, range_20, range_29_point_2]
+  output:
+    # Appendix 2, 2026-27: 130 and above 4%, 70-129 7%, 40-69 10%,
+    # 30-39 14%, less than 30 16%. 29.2 miles rounds up to 30 (s. 139(2)(b)).
+    company_car_appropriate_percentage: [0.04, 0.07, 0.1, 0.14, 0.16, 0.14]
+    company_car_benefit: [1_280, 2_240, 3_200, 4_480, 5_120, 4_480]
+
+- name: 1-50 g/km cars take one rate from 2028-29 whatever their electric range
+  period: 2029
+  absolute_error_margin: 0.01
+  input:
+    people:
+      range_130:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 50
+        company_car_electric_range: 130
+      range_20:
+        company_car_list_price: 32_000
+        company_car_co2_emissions: 1
+        company_car_electric_range: 20
+    benunits:
+      benunit:
+        members: [range_130, range_20]
+    households:
+      household:
+        members: [range_130, range_20]
+  output:
+    # Finance Act 2025 s. 6(2): 19% for 1-50 g/km in 2029-30.
+    company_car_appropriate_percentage: [0.19, 0.19]
+    company_car_benefit: [6_080, 6_080]
+
+- name: Zero-emission car in 2026-27
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 0
+    company_car_fuel_type: ELECTRIC
+  output:
+    # Appendix 2, 2026-27: 4%. £40,000 x 4% = £1,600.
+    company_car_appropriate_percentage: 0.04
+    company_car_benefit: 1_600
+
+- name: 2029-30 rates, the baseline for 2030-31
+  period: 2029
+  absolute_error_margin: 0.01
+  input:
+    people:
+      electric:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 0
+      band_65_74:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 74
+      band_75:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 79
+      high:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 200
+    benunits:
+      benunit:
+        members: [electric, band_65_74, band_75, high]
+    households:
+      household:
+        members: [electric, band_65_74, band_75, high]
+  output:
+    # Finance Act 2025 s. 6: 9% for 0 g/km, 23% for 65-74 g/km, 23% at
+    # 75-79 g/km, and a 39% maximum.
+    company_car_appropriate_percentage: [0.09, 0.23, 0.23, 0.39]
+    company_car_benefit: [3_600, 9_200, 9_200, 15_600]
+
+- name: 2030-31 keeps 2029-30's rates in the baseline
+  period: 2030
+  absolute_error_margin: 0.01
+  input:
+    people:
+      electric:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 0
+      hybrid:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 30
+        company_car_electric_range: 40
+      high:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 200
+    benunits:
+      benunit:
+        members: [electric, hybrid, high]
+    households:
+      household:
+        members: [electric, hybrid, high]
+  output:
+    company_car_appropriate_percentage: [0.09, 0.19, 0.39]
+
+- name: Capital contributions above £5,000 are capped
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_capital_contributions: 7_000
+    company_car_co2_emissions: 120
+  output:
+    # s. 132(3): the deduction is the lesser of the contributions and
+    # £5,000. 120 g/km is 30% (Appendix 2, 2026-27).
+    # (£40,000 - £5,000) x 30% = £10,500.
+    company_car_benefit: 10_500
+
+- name: Capital contributions below the cap are deducted in full
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_capital_contributions: 3_000
+    company_car_co2_emissions: 120
+  output:
+    # (£40,000 - £3,000) x 30% = £11,100.
+    company_car_benefit: 11_100
+
+- name: Car available for part of the year
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+    company_car_availability: 0.5
+  output:
+    # s. 143(3) deducts A x U / Y: £12,000 x 0.5 = £6,000.
+    company_car_benefit: 6_000
+
+- name: Payments for private use come off after the reduction for unavailability
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+    company_car_availability: 0.5
+    company_car_private_use_payments: 1_200
+  output:
+    # Steps 7 then 8 of s. 121(1): £12,000 x 0.5 - £1,200 = £4,800.
+    company_car_benefit: 4_800
+
+- name: Payments for private use above the benefit reduce it to nil
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+    company_car_private_use_payments: 13_000
+  output:
+    # s. 144(2).
+    company_car_benefit: 0
+
+- name: No benefit before 2020-21, the model's first year
+  period: 2019
+  absolute_error_margin: 0
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    company_car_benefit: 0
+
+- name: Out-of-range amounts are floored at zero and availability is kept between 0 and 1
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      negative_price:
+        company_car_list_price: -40_000
+        company_car_co2_emissions: 120
+      negative_amounts:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 120
+        company_car_capital_contributions: -5_000
+        company_car_private_use_payments: -1_200
+      availability_above_one:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 120
+        company_car_availability: 1.5
+      availability_below_zero:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: 120
+        company_car_availability: -0.5
+      negative_figures:
+        company_car_list_price: 40_000
+        company_car_co2_emissions: -10
+        company_car_electric_range: -10
+    benunits:
+      benunit:
+        members: [negative_price, negative_amounts, availability_above_one, availability_below_zero, negative_figures]
+    households:
+      household:
+        members: [negative_price, negative_amounts, availability_above_one, availability_below_zero, negative_figures]
+  output:
+    # A negative price is no car; negative contributions and payments are
+    # none; availability is capped at the whole year and floored at none.
+    # Negative CO2 and electric range figures are 0: the zero-emission rate.
+    has_company_car: [false, true, true, true, true]
+    company_car_appropriate_percentage: [0, 0.3, 0.3, 0.3, 0.04]
+    company_car_benefit: [0, 12_000, 12_000, 0, 1_600]
+
+- name: An electric car is zero-emission whatever CO2 figure is entered
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 150
+    company_car_fuel_type: ELECTRIC
+    company_car_private_fuel_provided: true
+  output:
+    # As for vehicle excise duty, the ELECTRIC fuel type gives a CO2 figure
+    # of 0: 4% in 2026-27, and no car fuel benefit (s. 149(4)).
+    company_car_appropriate_percentage: 0.04
+    company_car_benefit: 1_600
+    car_fuel_benefit: 0
+
+- name: A car at 0 g/km takes no diesel supplement
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 0
+    company_car_fuel_type: DIESEL_NON_RDE2
+  output:
+    # A car that cannot emit CO2 is not propelled by diesel (s. 141(3)).
+    company_car_appropriate_percentage: 0.04
+    company_car_benefit: 1_600
+
+- name: A CO2 figure that rounds down to 0 is zero-emission for both benefits
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 0.5
+    company_car_private_fuel_provided: true
+  output:
+    company_car_appropriate_percentage: 0.04
+    car_fuel_benefit: 0
diff --git a/policyengine_uk/tests/policy/baseline/gov/hmrc/national_insurance/class_1a/ni_class_1a.yaml b/policyengine_uk/tests/policy/baseline/gov/hmrc/national_insurance/class_1a/ni_class_1a.yaml
new file mode 100644
index 0000000000..0e452d55a5
--- /dev/null
+++ b/policyengine_uk/tests/policy/baseline/gov/hmrc/national_insurance/class_1a/ni_class_1a.yaml
@@ -0,0 +1,98 @@
+# Class 1A contributions on benefits in kind (SSCBA 1992 s. 10). The Class
+# 1A percentage is the secondary Class 1 percentage for the year (s. 10(5)):
+# 13.8% to 2024-25 and 15% from 2025-26, except 14.53% for 2022-23 (Health
+# and Social Care Levy (Repeal) Act 2022 Schedule paragraph 1(2)). Each case
+# has a petrol car with a list price of £40,000 emitting 120 g/km, whose
+# appropriate percentage is 29% to 2024-25 and 30% from 2025-26 (HMRC 480
+# Appendix 2), so its benefit is £11,600, then £12,000.
+
+- name: Class 1A at 13.8% in 2021-22
+  period: 2021
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    # £11,600 x 13.8% = £1,600.80.
+    ni_class_1a: 1_600.8
+
+- name: Class 1A at the 2022-23 rate of 14.53%, not the secondary percentage at 30 April
+  period: 2022
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    # £11,600 x 14.53% = £1,685.48.
+    ni_class_1a: 1_685.48
+
+- name: Class 1A back at 13.8% in 2023-24
+  period: 2023
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    ni_class_1a: 1_600.8
+
+- name: Class 1A at 15% from 2025-26
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    # £12,000 x 15% = £1,800.
+    ni_class_1a: 1_800
+
+- name: Class 1A on the car and car fuel benefits together
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+    company_car_private_fuel_provided: true
+  output:
+    # Car £12,000 plus fuel £29,200 x 30% = £8,760: £20,760 x 15% = £3,114.
+    benefits_in_kind: 20_760
+    ni_class_1a: 3_114
+
+- name: Class 1A reaches employer NI alongside secondary Class 1
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 40_000
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    # Secondary Class 1: (£40,000 - £5,000) x 15% = £5,250, on pay only.
+    ni_class_1_employer: 5_250
+    ni_class_1a: 1_800
+    ni_employer: 7_050
+
+- name: Class 1A is due for an earner under 21, whose pay is zero-rated for secondary Class 1
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 20
+    employment_income: 30_000
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    ni_class_1_employer: 0
+    ni_class_1a: 1_800
+    ni_employer: 1_800
+
+- name: Total National Insurance includes Class 1A
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    age: 40
+    employment_income: 40_000
+    company_car_list_price: 40_000
+    company_car_co2_emissions: 120
+  output:
+    # Employee Class 1: (£40,000 - £12,570) x 8% = £2,194.40, on pay only.
+    ni_class_1_employee: 2_194.4
+    total_national_insurance: 2_194.4 + 7_050
diff --git a/policyengine_uk/tests/test_company_car_benefit.py b/policyengine_uk/tests/test_company_car_benefit.py
new file mode 100644
index 0000000000..8c4be71795
--- /dev/null
+++ b/policyengine_uk/tests/test_company_car_benefit.py
@@ -0,0 +1,409 @@
+"""The company car benefit against HMRC's published rates, and its reforms.
+
+1. Published rates: for every tax year from 2020-21 to 2029-30, the
+   appropriate percentage at both ends of each band equals the rate HMRC
+   publishes for it: HMRC 480 Appendix 2 for 2020-21 to 2026-27 (its
+   2022-23 table holds to 2024-25), HMRC's future rates table for 2027-28,
+   and the tables in Finance Act 2025 ss. 5 and 6 for 2028-29 and 2029-30.
+   In 2020-21 and 2021-22 cars first registered before 6 April 2020 take
+   the NEDC column and later cars the WLTP column (ITEPA 2003 s. 139A).
+   A diesel car not meeting RDE2 adds 4 points, up to the maximum.
+2. Budget 2026: the company_car_tax_rise_2030 scenario raises every
+   appropriate percentage for 2030-31 by one point, to a maximum of 40%. It
+   changes a company car holder's income tax and their employer's Class 1A,
+   nothing else (their student loan repayment included), and nobody else's
+   tax; 2029-30 is unchanged. COMPANY_CAR_TAX_RISE_2030 passed as a reform
+   dict gives the same results.
+3. Employer NI: Class 1A follows the secondary percentage (SSCBA 1992
+   s. 10(5)), so an employer rate reform moves it. The employer NI
+   incidence covers secondary Class 1 only, so no household bears Class 1A:
+   the fixed-employer-cost pay response and the employer cost change that
+   the capital and consumer channels spread leave it out. And
+   baseline_employer_cost and adjusted_employer_cost still equal each
+   simulation's employer_cost for a company car holder, as they do for
+   everyone else.
+
+Comparisons allow float32 rounding.
+"""
+
+import numpy as np
+import pytest
+
+from policyengine_uk import Simulation
+from policyengine_uk.scenarios import company_car_tax_rise_2030
+from policyengine_uk.scenarios.company_car_tax_rise_2030 import (
+    COMPANY_CAR_TAX_RISE_2030,
+)
+
+pytestmark = pytest.mark.usefixtures("cloned_uk_tax_benefit_system")
+
+# Each table, in percentage points: the rate for 0 g/km; for 1 to 50 g/km by
+# electric range (130 miles or more, 70-129, 40-69, 30-39, under 30); for
+# 51-54, 55-59, 60-64, 65-69 and 70-74 g/km; and for each 5 g/km band from
+# 75-79 to 165-169 g/km, then 170 g/km and above.
+NEDC_2020 = (
+    0,
+    [2, 5, 8, 12, 14],
+    [15, 16, 17, 18, 19],
+    [20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 37],
+)
+WLTP_2020 = (
+    0,
+    [0, 3, 6, 10, 12],
+    [13, 14, 15, 16, 17],
+    [18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37],
+)
+NEDC_2021 = (
+    1,
+    [2, 5, 8, 12, 14],
+    [15, 16, 17, 18, 19],
+    [20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 37],
+)
+WLTP_2021 = (
+    1,
+    [1, 4, 7, 11, 13],
+    [14, 15, 16, 17, 18],
+    [19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37],
+)
+ALL_CARS_2022 = (
+    2,
+    [2, 5, 8, 12, 14],
+    [15, 16, 17, 18, 19],
+    [20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 37],
+)
+ALL_CARS_2025 = (
+    3,
+    [3, 6, 9, 13, 15],
+    [16, 17, 18, 19, 20],
+    [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 37, 37],
+)
+ALL_CARS_2026 = (
+    4,
+    [4, 7, 10, 14, 16],
+    [17, 18, 19, 20, 21],
+    [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 37, 37],
+)
+ALL_CARS_2027 = (
+    5,
+    [5, 8, 11, 15, 17],
+    [18, 19, 20, 21, 21],
+    [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 37, 37],
+)
+# Finance Act 2025 ss. 5 and 6: one rate for 1 to 50 g/km, a 65-74 g/km
+# band, and from 75 g/km 22% (then 23%) plus one point for each 5 g/km, up
+# to 38% (then 39%).
+ALL_CARS_2028 = (
+    7,
+    [18] * 5,
+    [19, 20, 21, 22, 22],
+    [22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 38, 38, 38],
+)
+ALL_CARS_2029 = (
+    9,
+    [19] * 5,
+    [20, 21, 22, 23, 23],
+    [23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 39, 39, 39],
+)
+# Budget 2026 for 2030-31: one point above 2029-30 in every band, up to 40%.
+BUDGET_2026_2030 = (
+    10,
+    [20] * 5,
+    [21, 22, 23, 24, 24],
+    [24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 40, 40, 40],
+)
+
+# (year, first registered on or after 6 April 2020, table)
+PUBLISHED = [
+    (2020, False, NEDC_2020),
+    (2020, True, WLTP_2020),
+    (2021, False, NEDC_2021),
+    (2021, True, WLTP_2021),
+    (2022, False, ALL_CARS_2022),
+    (2022, True, ALL_CARS_2022),
+    (2023, True, ALL_CARS_2022),
+    (2024, False, ALL_CARS_2022),
+    (2025, False, ALL_CARS_2025),
+    (2026, True, ALL_CARS_2026),
+    (2027, False, ALL_CARS_2027),
+    (2028, False, ALL_CARS_2028),
+    (2029, False, ALL_CARS_2029),
+]
+
+RANGE_BANDS = [(130, 300), (70, 129), (40, 69), (30, 39), (0, 29)]
+CO2_BANDS = [(51, 54), (55, 59), (60, 64), (65, 69), (70, 74)]
+GRADUATED_BANDS = [(low, low + 4) for low in range(75, 170, 5)] + [(170, 250)]
+
+
+def band_points(table):
+    """(CO2 g/km, electric range in miles, expected rate) at each band's ends."""
+    zero, by_range, by_co2, graduated = table
+    points = [(0, 0, zero)]
+    for (low, high), rate in zip(RANGE_BANDS, by_range):
+        for co2 in (1, 50):
+            points += [(co2, low, rate), (co2, high, rate)]
+    for bands, rates in ((CO2_BANDS, by_co2), (GRADUATED_BANDS, graduated)):
+        for (low, high), rate in zip(bands, rates):
+            points += [(low, 0, rate), (high, 0, rate)]
+    return points
+
+
+def situation(year, cars):
+    """One person per car, each with the given company car inputs."""
+    people = {
+        f"person_{i}": {
+            "age": {year: 40},
+            "employment_income": {year: 40_000},
+            **{name: {year: value} for name, value in car.items()},
+        }
+        for i, car in enumerate(cars)
+    }
+    return {
+        "people": people,
+        "benunits": {f"benunit_{name}": {"members": [name]} for name in people},
+        "households": {f"household_{name}": {"members": [name]} for name in people},
+    }
+
+
+def values(simulation, variable, year):
+    return np.asarray(simulation.calculate(variable, year), dtype=float)
+
+
+def appropriate_percentages(year, cars, **kwargs):
+    simulation = Simulation(situation=situation(year, cars), **kwargs)
+    return values(simulation, "company_car_appropriate_percentage", year)
+
+
+def cars_at(points, registered, fuel_type="PETROL"):
+    return [
+        {
+            "company_car_list_price": 30_000,
+            "company_car_co2_emissions": co2,
+            "company_car_electric_range": electric_range,
+            "company_car_registered_from_6_april_2020": registered,
+            "company_car_fuel_type": fuel_type,
+        }
+        for co2, electric_range, _ in points
+    ]
+
+
+@pytest.mark.parametrize("year, registered, table", PUBLISHED)
+def test_appropriate_percentages_match_published_rates(year, registered, table):
+    points = band_points(table)
+    actual = appropriate_percentages(year, cars_at(points, registered))
+    expected = np.array([rate for *_, rate in points]) / 100
+    np.testing.assert_allclose(actual, expected, atol=1e-6)
+
+
+@pytest.mark.parametrize("year, registered, table", PUBLISHED)
+def test_diesel_supplement_adds_four_points_up_to_the_maximum(year, registered, table):
+    # HMRC 480 paragraph 12.29: a diesel car not meeting RDE2 adds 4 points,
+    # subject to the overall maximum, which is the table's highest rate.
+    points = [point for point in band_points(table) if point[0] > 0]
+    maximum = max(table[3])
+    actual = appropriate_percentages(
+        year, cars_at(points, registered, "DIESEL_NON_RDE2")
+    )
+    expected = np.minimum(np.array([rate for *_, rate in points]) + 4, maximum) / 100
+    np.testing.assert_allclose(actual, expected, atol=1e-6)
+
+
+def test_figures_are_rounded_as_section_139_rounds_them():
+    # s. 139(2): CO2 down to a whole number, electric range up; s. 139(4):
+    # from 75 g/km, CO2 down to a multiple of 5. 2026-27 rates.
+    cars = [
+        {
+            "company_car_list_price": 30_000,
+            "company_car_co2_emissions": co2,
+            "company_car_electric_range": electric_range,
+        }
+        for co2, electric_range in [(50.9, 130), (49, 29.1), (74.9, 0), (79.9, 0)]
+    ]
+    actual = appropriate_percentages(2026, cars)
+    np.testing.assert_allclose(actual, [0.04, 0.14, 0.21, 0.21], atol=1e-6)
+
+
+def test_2030_31_rise_sets_the_budget_2026_rates():
+    points = band_points(BUDGET_2026_2030)
+    cars = cars_at(points, registered=False)
+    baseline = appropriate_percentages(2030, cars)
+    reformed = appropriate_percentages(2030, cars, scenario=company_car_tax_rise_2030)
+    expected = np.array([rate for *_, rate in points]) / 100
+    np.testing.assert_allclose(reformed, expected, atol=1e-6)
+    # The baseline keeps 2029-30's rates.
+    expected_baseline = np.array([rate for *_, rate in band_points(ALL_CARS_2029)])
+    np.testing.assert_allclose(baseline, expected_baseline / 100, atol=1e-6)
+
+
+# A company car holder with private fuel and a Plan 2 student loan, and an
+# employee without a car.
+HOLDER = {
+    "company_car_list_price": 40_000,
+    "company_car_co2_emissions": 120,
+    "company_car_private_fuel_provided": True,
+    "student_loan_plan": "PLAN_2",
+}
+UNCHANGED_FOR_HOLDER = [
+    "ni_class_1_employer",
+    "ni_class_1_employee",
+    "employment_income",
+    "employer_ni_fixed_employer_cost_change",
+    "student_loan_repayment",
+    "plan_2_interest_rate",
+]
+TAX_AND_INCOME = [
+    "income_tax",
+    "ni_class_1a",
+    "uc_individual_earned_income_before_mif",
+] + UNCHANGED_FOR_HOLDER
+
+
+@pytest.mark.parametrize("year", [2029, 2030, 2031])
+def test_2030_31_rise_changes_only_holders_income_tax_and_class_1a(year):
+    cars = [HOLDER, {}]
+    baseline = Simulation(situation=situation(year, cars))
+    reformed = Simulation(
+        situation=situation(year, cars), scenario=company_car_tax_rise_2030
+    )
+    change = {
+        variable: values(reformed, variable, year) - values(baseline, variable, year)
+        for variable in TAX_AND_INCOME + ["benefits_in_kind", "gov_tax"]
+    }
+    benefit_change = change["benefits_in_kind"][0]
+    if year == 2029:
+        # The rise starts on 6 April 2030.
+        for variable, difference in change.items():
+            np.testing.assert_allclose(difference, 0, atol=1e-2, err_msg=variable)
+        return
+    # One point on the car (£40,000) and on the fuel multiplier.
+    multiplier = baseline.tax_benefit_system.parameters(
+        f"{year}-01-01"
+    ).gov.hmrc.income_tax.benefits_in_kind.car_fuel.multiplier
+    assert benefit_change == pytest.approx(0.01 * (40_000 + multiplier), abs=0.05)
+    # Pay of £40,000 plus about £23,000 of car and fuel benefits is in the
+    # higher rate band, and below the personal allowance taper.
+    assert change["income_tax"][0] == pytest.approx(0.4 * benefit_change, abs=0.05)
+    assert change["ni_class_1a"][0] == pytest.approx(0.15 * benefit_change, abs=0.05)
+    assert change["gov_tax"][0] == pytest.approx(
+        change["income_tax"][0] + change["ni_class_1a"][0], abs=0.05
+    )
+    # UC earnings lose the extra income tax and nothing else.
+    assert change["uc_individual_earned_income_before_mif"][0] == pytest.approx(
+        -change["income_tax"][0], abs=0.05
+    )
+    for variable in UNCHANGED_FOR_HOLDER:
+        np.testing.assert_allclose(change[variable][0], 0, atol=1e-6, err_msg=variable)
+    # Nothing changes for the employee without a car.
+    for variable, difference in change.items():
+        np.testing.assert_allclose(difference[1], 0, atol=1e-2, err_msg=variable)
+
+
+def test_a_company_car_raises_gov_tax_by_its_income_tax_and_class_1a():
+    # The same employee, with the same student loan, without the car.
+    without_the_car = {
+        name: value for name, value in HOLDER.items() if not name.startswith("company")
+    }
+    with_car = Simulation(situation=situation(2026, [HOLDER]))
+    without_car = Simulation(situation=situation(2026, [without_the_car]))
+
+    def change(variable):
+        return (values(with_car, variable, 2026) - values(without_car, variable, 2026))[
+            0
+        ]
+
+    assert change("ni_class_1a") > 0
+    # Student loan repayments are in gov_tax but leave the benefit out.
+    assert change("student_loan_repayment") == 0
+    assert change("gov_tax") == pytest.approx(
+        change("income_tax") + change("ni_class_1a"), abs=0.05
+    )
+    # The benefit is not cash: household income falls by the tax on it.
+    assert change("household_net_income") == pytest.approx(
+        -change("income_tax"), abs=0.05
+    )
+
+
+EMPLOYER_RATE = "gov.hmrc.national_insurance.class_1.employer_scale[1].rate"
+
+
+def test_class_1a_follows_an_employer_rate_reform_outside_the_fixed_cost_response():
+    reform = {EMPLOYER_RATE: {"2026-04-06.2100-12-31": 0.16}}
+    cars = [HOLDER, {}]
+    baseline = Simulation(situation=situation(2026, cars))
+    reformed = Simulation(situation=situation(2026, cars), reform=reform)
+    benefits = values(baseline, "benefits_in_kind", 2026)
+    # SSCBA 1992 s. 10(5): the Class 1A percentage is the secondary
+    # percentage for the year.
+    np.testing.assert_allclose(
+        values(reformed, "ni_class_1a", 2026), 0.16 * benefits, rtol=1e-6
+    )
+    # The pay response holds employer cost before Class 1A, so the holder's
+    # pay moves exactly as the other employee's does, and so does the cost
+    # change the capital and consumer channels would spread.
+    pay_change = values(reformed, "employer_ni_fixed_employer_cost_change", 2026)
+    assert pay_change[0] < 0
+    assert pay_change[0] == pytest.approx(pay_change[1], abs=0.01)
+    cost_change = values(reformed, "adjusted_employer_cost", 2026) - values(
+        reformed, "baseline_employer_cost", 2026
+    )
+    assert cost_change[0] == pytest.approx(cost_change[1], abs=0.01)
+    # Agreement: the incidence variables' costs equal employer_cost in each
+    # simulation, for the holder too.
+    np.testing.assert_allclose(
+        values(reformed, "baseline_employer_cost", 2026),
+        values(reformed.baseline, "employer_cost", 2026),
+        atol=0.01,
+    )
+    np.testing.assert_allclose(
+        values(reformed, "adjusted_employer_cost", 2026),
+        values(reformed, "employer_cost", 2026),
+        atol=0.01,
+    )
+
+
+@pytest.mark.parametrize("year", [2030, 2031, 2035])
+def test_the_parameter_changes_as_a_reform_dict_match_the_scenario(year):
+    cars = [HOLDER, {}]
+    from_scenario = Simulation(
+        situation=situation(year, cars), scenario=company_car_tax_rise_2030
+    )
+    from_dict = Simulation(
+        situation=situation(year, cars), reform=COMPANY_CAR_TAX_RISE_2030
+    )
+    for variable in ["company_car_appropriate_percentage", "income_tax", "gov_tax"]:
+        np.testing.assert_allclose(
+            values(from_dict, variable, year),
+            values(from_scenario, variable, year),
+            atol=1e-6,
+            err_msg=variable,
+        )
+
+
+INCIDENCE = "gov.contrib.policyengine.employer_ni"
+
+
+def test_no_household_bears_the_class_1a_on_the_2030_31_rise():
+    # With half of an employer NI change borne by employees, the rest would
+    # go to capital and consumers through adjusted_employer_cost less
+    # baseline_employer_cost. Neither covers Class 1A, so the rise's Class 1A
+    # moves no pay and leaves nothing for those channels to spread.
+    reform = {
+        **COMPANY_CAR_TAX_RISE_2030,
+        f"{INCIDENCE}.employee_incidence": {"2030-04-06.2100-12-31": 0.5},
+    }
+    simulation = Simulation(situation=situation(2030, [HOLDER]), reform=reform)
+    class_1a_change = values(simulation, "ni_class_1a", 2030) - values(
+        simulation.baseline, "ni_class_1a", 2030
+    )
+    assert class_1a_change[0] > 0
+    for variable in ["employer_ni_fixed_employer_cost_change", "employment_income"]:
+        np.testing.assert_allclose(
+            values(simulation, variable, 2030),
+            values(simulation.baseline, variable, 2030),
+            atol=1e-6,
+            err_msg=variable,
+        )
+    np.testing.assert_allclose(
+        values(simulation, "adjusted_employer_cost", 2030),
+        values(simulation, "baseline_employer_cost", 2030),
+        atol=0.01,
+    )
diff --git a/policyengine_uk/utils/company_car.py b/policyengine_uk/utils/company_car.py
new file mode 100644
index 0000000000..0bc876ffc3
--- /dev/null
+++ b/policyengine_uk/utils/company_car.py
@@ -0,0 +1,27 @@
+"""Inputs of the company car and car fuel benefits, as the formulas read them."""
+
+from policyengine_core.model_api import max_, min_, where
+import numpy as np
+
+
+def co2_emissions_figure(person, period):
+    """The company car's CO2 emissions figure for ITEPA 2003 s. 139.
+
+    Rounded down to a whole number (s. 139(2)(a)). A car of the ELECTRIC
+    fuel type (electric or other zero emission) is taken to have a figure of
+    0 whatever CO2 figure is entered, as for vehicle excise duty, so a car is
+    zero-emission for both the appropriate percentage and the car fuel
+    benefit (s. 149(4)) exactly when this is 0.
+    """
+    fuel_type = person("company_car_fuel_type", period)
+    co2 = np.floor(max_(person("company_car_co2_emissions", period), 0))
+    return where(fuel_type == fuel_type.possible_values.ELECTRIC, 0, co2)
+
+
+def share_of_year_available(person, period):
+    """The share of the tax year the company car is available, from 0 to 1.
+
+    Both benefits are reduced in proportion to the days the car is
+    unavailable (ITEPA 2003 ss. 143(3) and 152(1)).
+    """
+    return min_(max_(person("company_car_availability", period), 0), 1)
diff --git a/policyengine_uk/utils/pensions.py b/policyengine_uk/utils/pensions.py
index be14ef3e7c..ea9ef772a3 100644
--- a/policyengine_uk/utils/pensions.py
+++ b/policyengine_uk/utils/pensions.py
@@ -27,9 +27,10 @@ def relevant_uk_earnings(person, period, hmrc):
     """FA 2004 s.189(2) relevant UK earnings.
 
     Employment income chargeable to income tax is net taxable earnings
-    (ITEPA 2003 ss.9(2) and 11): pay and employer-paid taxable SSP, SMP and
-    SPP (employment_benefits), which the model holds separately from wages,
-    less the allowable expenses in s.327(3). s.327(5) also lists the deductions for pension contributions
+    (ITEPA 2003 ss.9(2) and 11): pay, employer-paid taxable SSP, SMP and
+    SPP (employment_benefits) and taxable benefits in kind (benefits_in_kind,
+    HMRC PTM044100), which the model holds separately from wages, less the
+    allowable expenses in s.327(3). s.327(5) also lists the deductions for pension contributions
     (FA 2004 ss.188-194), but those are the relief that these earnings limit,
     so they are not taken off; the limit would otherwise depend on itself.
     Trading income is the profit chargeable under ITTOIA 2005 Part 2, before
diff --git a/policyengine_uk/utils/student_loans.py b/policyengine_uk/utils/student_loans.py
new file mode 100644
index 0000000000..845850f0ac
--- /dev/null
+++ b/policyengine_uk/utils/student_loans.py
@@ -0,0 +1,24 @@
+"""The income on which student loan repayments and interest are worked out."""
+
+from policyengine_core.model_api import max_, min_
+
+
+def student_loan_income(person, period):
+    """Net income less the benefits in kind it holds.
+
+    Benefits in kind are not repayment income: Self Assessment leaves out
+    the car benefits of ITEPA 2003 Part 3 Chapter 6 (SI 2009/470 reg.
+    29(4)(e)), and PAYE deducts repayments from Class 1 earnings only
+    (reg. 41). Plan 2 interest income is the same income (reg. 21A(11)).
+
+    Allowable deductions come off pay and benefits together (ITEPA 2003
+    s. 11), so where they exceed pay, taxable employment income holds only
+    part of the benefits. Taxable employment income is the pay and benefits
+    less deductions, floored at zero, so it holds the smaller of itself and
+    the benefits: only that much comes off.
+    """
+    benefits_in_net_income = min_(
+        person("taxable_employment_income", period),
+        person("benefits_in_kind", period),
+    )
+    return max_(person("net_income", period) - benefits_in_net_income, 0)
diff --git a/policyengine_uk/variables/contrib/policyengine/employer_ni/employer_cost.py b/policyengine_uk/variables/contrib/policyengine/employer_ni/employer_cost.py
index 98ca7b95ea..659dbacdf6 100644
--- a/policyengine_uk/variables/contrib/policyengine/employer_ni/employer_cost.py
+++ b/policyengine_uk/variables/contrib/policyengine/employer_ni/employer_cost.py
@@ -3,6 +3,14 @@
 
 class employer_cost(Variable):
     label = "employer cost"
+    documentation = (
+        "Pay, statutory sick, maternity and paternity pay, employer pension "
+        "contributions and the secondary Class 1 contributions on them. "
+        "Benefits in kind and the Class 1A contributions on them are left "
+        "out, as baseline_employer_cost and adjusted_employer_cost leave "
+        "them out, so a fixed-employer-cost response to an employer NI "
+        "reform holds this cost."
+    )
     entity = Person
     definition_period = YEAR
     value_type = float
@@ -20,7 +28,7 @@ def formula(person, period, parameters):
         )
         return (
             person("employment_income", period)
-            + person("ni_employer", period)
+            + person("ni_class_1_employer", period)
             + person("employer_pension_contributions", period)
             + benefits
         )
diff --git a/policyengine_uk/variables/gov/dwp/housing_benefit/applicable_income/_net_earnings.py b/policyengine_uk/variables/gov/dwp/housing_benefit/applicable_income/_net_earnings.py
index 993bfd0a45..82088a86be 100644
--- a/policyengine_uk/variables/gov/dwp/housing_benefit/applicable_income/_net_earnings.py
+++ b/policyengine_uk/variables/gov/dwp/housing_benefit/applicable_income/_net_earnings.py
@@ -40,7 +40,10 @@ def person_net_earnings(
     The existing tax-attribution approximation uses earnings' share of an
     explicit raw income base including statutory pay, before losses, and tax
     before the Winter Fuel Payment charge. This is independent of the income
-    tax definition of total_income and its component list. Housing Benefit
+    tax definition of total_income and its component list. Benefits in kind
+    are not earnings (reg 35(2)(a)), but PAYE collects the tax on them from
+    the employment's pay, so they count with earnings in that share and in
+    the base, though not in the earnings themselves. Housing Benefit
     (housing_benefit_net_earnings), Council Tax Reduction
     (council_tax_reduction_net_earnings) and Income Support
     (income_support_net_earnings) use these deductions.
@@ -73,10 +76,14 @@ def person_net_earnings(
             "taxable_miscellaneous_income",
         ]
     )
+    # Benefits in kind are taxed with the pay but are not earnings.
+    benefits_in_kind = person("benefits_in_kind", period)
+    income_before_losses = income_before_losses + benefits_in_kind
+    taxed_with_earnings = earnings + benefits_in_kind
     earnings_share = np.divide(
-        earnings,
+        taxed_with_earnings,
         income_before_losses,
-        out=np.zeros_like(earnings),
+        out=np.zeros_like(taxed_with_earnings),
         where=income_before_losses > 0,
     )
     # Tax before the winter fuel payment charge: the charge recovers a
diff --git a/policyengine_uk/variables/gov/hmrc/income_tax/bases/taxable_employment_income.py b/policyengine_uk/variables/gov/hmrc/income_tax/bases/taxable_employment_income.py
index cb82e8af7f..44e95a173d 100644
--- a/policyengine_uk/variables/gov/hmrc/income_tax/bases/taxable_employment_income.py
+++ b/policyengine_uk/variables/gov/hmrc/income_tax/bases/taxable_employment_income.py
@@ -16,4 +16,8 @@ def formula(person, period, parameters):
         taxable_earnings = person("employment_income", period)
         deductions = add(person, period, ["employment_deductions"])
         benefits = person("employment_benefits", period)
-        return max_(0, taxable_earnings + benefits - deductions)
+        # Benefits code earnings (ITEPA 2003 s. 63), held apart from pay and
+        # statutory pay because Class 1 NICs and the means tests' earnings
+        # leave them out.
+        benefits_in_kind = person("benefits_in_kind", period)
+        return max_(0, taxable_earnings + benefits + benefits_in_kind - deductions)
diff --git a/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/benefits_in_kind.py b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/benefits_in_kind.py
new file mode 100644
index 0000000000..355ce17718
--- /dev/null
+++ b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/benefits_in_kind.py
@@ -0,0 +1,41 @@
+from policyengine_uk.model_api import *
+
+
+class benefits_in_kind(Variable):
+    value_type = float
+    entity = Person
+    label = "Taxable benefits in kind"
+    documentation = (
+        "Benefits the person's employment provides that the benefits code "
+        "(ITEPA 2003 s. 63) treats as earnings: the company car and car "
+        "fuel benefits. Income tax charges them through "
+        "taxable_employment_income, and employers pay Class 1A NICs on them. "
+        "They are not earnings for Class 1 NICs, nor for the earnings tests "
+        "of Universal Credit (UC Regulations 2013 reg. 55(2)(a)), Housing "
+        "Benefit (HB Regulations 2006 reg. 35(2)(a)) and Council Tax "
+        "Reduction, so they are kept out of employment_income and "
+        "employment_benefits; those tests do deduct the income tax on them. "
+        "Student loan repayments and the Plan 2 interest rate leave them "
+        "out too (SI 2009/470 regs. 29(4)(e) and 41). Other benefits in kind "
+        "and vans are not modelled."
+    )
+    definition_period = YEAR
+    unit = GBP
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 63 (the benefits code)",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/63",
+        ),
+        dict(
+            title="Universal Credit Regulations 2013 reg. 55(2)(a)",
+            href="https://www.legislation.gov.uk/uksi/2013/376/regulation/55",
+        ),
+        dict(
+            title="Housing Benefit Regulations 2006 reg. 35(2)(a)",
+            href="https://www.legislation.gov.uk/uksi/2006/213/regulation/35",
+        ),
+    ]
+    adds = [
+        "company_car_benefit",
+        "car_fuel_benefit",
+    ]
diff --git a/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/car_fuel_benefit.py b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/car_fuel_benefit.py
new file mode 100644
index 0000000000..285bc3723f
--- /dev/null
+++ b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/car_fuel_benefit.py
@@ -0,0 +1,52 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.utils.company_car import (
+    co2_emissions_figure,
+    share_of_year_available,
+)
+
+
+class car_fuel_benefit(Variable):
+    value_type = float
+    entity = Person
+    label = "Car fuel benefit"
+    documentation = (
+        "The cash equivalent of fuel provided for private use of the "
+        "person's company car, treated as earnings from their employment "
+        "(ITEPA 2003 s. 149): the car's appropriate percentage of the car "
+        "fuel benefit charge multiplier (s. 150), reduced in proportion to "
+        "the days the car is unavailable (s. 152(1)). It is nil where the "
+        "person makes good the whole cost of private fuel (s. 151), and for "
+        "a car that cannot emit CO2, whose energy is not fuel (s. 149(4)). "
+        "Payments for private use and capital contributions do not reduce "
+        "it. Calculated from 2020-21."
+    )
+    definition_period = YEAR
+    unit = GBP
+    defined_for = "has_company_car"
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 149",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/149",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 150",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/150",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 152",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/152",
+        ),
+        dict(
+            title="HMRC 480 Chapter 13: taxable fuel provided for company cars and vans",
+            href="https://www.gov.uk/guidance/taxable-fuel-provided-for-company-cars-and-vans-480-chapter-13",
+        ),
+    ]
+
+    def formula_2020(person, period, parameters):
+        p = parameters(period).gov.hmrc.income_tax.benefits_in_kind.car_fuel
+        fuel_provided = person("company_car_private_fuel_provided", period)
+        # s. 149(4): the same test as the zero-emission rate in s. 139.
+        can_emit_co2 = co2_emissions_figure(person, period) > 0
+        full_year = p.multiplier * person("company_car_appropriate_percentage", period)
+        availability = share_of_year_available(person, period)
+        return fuel_provided * can_emit_co2 * full_year * availability
diff --git a/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/company_car_appropriate_percentage.py b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/company_car_appropriate_percentage.py
new file mode 100644
index 0000000000..bb9b07b21d
--- /dev/null
+++ b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/company_car_appropriate_percentage.py
@@ -0,0 +1,97 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.utils.company_car import co2_emissions_figure
+
+
+class company_car_appropriate_percentage(Variable):
+    value_type = float
+    entity = Person
+    label = "Appropriate percentage of the person's company car"
+    documentation = (
+        "The share of the company car's price taxed each year as its "
+        "benefit, which the car fuel benefit also uses (ITEPA 2003 s. 139). "
+        "A car emitting 0 g/km takes the zero-emission rate, one emitting 1 "
+        "to 50 g/km a rate by its electric range, and one emitting 51 to "
+        "74 g/km a rate from the table. From 75 g/km the rate is the base "
+        "rate plus one point for each full 5 g/km above 75, up to the "
+        "maximum. A car of the ELECTRIC fuel type is taken to emit 0 g/km. "
+        "A diesel car not meeting the Euro 6d (RDE2) standard adds the "
+        "diesel supplement, within the maximum (s. 141). In 2020-21 and "
+        "2021-22 a car first registered on or after 6 April 2020 takes the "
+        "s. 139A rates. Zero for a person without a company car. Cars "
+        "without a CO2 emissions figure (s. 140) and cars first registered "
+        "before 1 January 1998 (s. 142) are not modelled. Calculated from "
+        "2020-21."
+    )
+    definition_period = YEAR
+    unit = "/1"
+    defined_for = "has_company_car"
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 139",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/139",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 141",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/141",
+        ),
+        dict(
+            title="Finance Act 2020 ss. 9 and 10 (s. 139A for 2020-21 and 2021-22)",
+            href="https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted",
+        ),
+    ]
+
+    def formula_2020(person, period, parameters):
+        p = parameters(
+            period
+        ).gov.hmrc.income_tax.benefits_in_kind.company_car.appropriate_percentage
+        # s. 139(2): the CO2 emissions figure is rounded down to a whole
+        # number and the electric range figure up.
+        co2 = co2_emissions_figure(person, period)
+        electric_range = np.ceil(max_(person("company_car_electric_range", period), 0))
+        from_april_2020 = p.registered_from_6_april_2020
+        takes_s139a_rates = from_april_2020.in_effect & person(
+            "company_car_registered_from_6_april_2020", period
+        )
+        electric_range_rate = where(
+            takes_s139a_rates,
+            from_april_2020.electric_range.calc(electric_range),
+            p.electric_range.calc(electric_range),
+        )
+        co2_band_rate = where(
+            takes_s139a_rates,
+            from_april_2020.co2_band.calc(co2),
+            p.co2_band.calc(co2),
+        )
+        # s. 139(3) and (4): from the threshold, the base rate plus the
+        # increment for each full step above it, up to the maximum.
+        graduated = p.graduated
+        base_rate = where(
+            takes_s139a_rates,
+            from_april_2020.graduated_base_rate,
+            graduated.base_rate,
+        )
+        steps = np.floor((co2 - graduated.threshold) / graduated.step)
+        graduated_rate = min_(
+            base_rate + graduated.increment * max_(steps, 0), p.maximum
+        )
+        # Finance Act 2020 ss. 9(2)(a) and 10(2)(a) give the s. 139 table the
+        # s. 139A rate for 0 g/km, so both schedules use the one
+        # zero-emission rate.
+        zero_emission = co2 == 0
+        rate = select(
+            [
+                zero_emission,
+                co2 <= p.electric_range_co2_limit,
+                co2 < graduated.threshold,
+            ],
+            [p.zero_emission, electric_range_rate, co2_band_rate],
+            default=graduated_rate,
+        )
+        # s. 141: a diesel car not meeting the Euro 6d standard adds the
+        # supplement, up to the maximum. A car that cannot emit CO2 is not
+        # propelled by diesel (s. 141(3)).
+        fuel_type = person("company_car_fuel_type", period)
+        diesel = (fuel_type == fuel_type.possible_values.DIESEL_NON_RDE2) & ~(
+            zero_emission
+        )
+        return where(diesel, min_(rate + p.diesel_supplement, p.maximum), rate)
diff --git a/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/company_car_benefit.py b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/company_car_benefit.py
new file mode 100644
index 0000000000..68663af5d7
--- /dev/null
+++ b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/company_car_benefit.py
@@ -0,0 +1,55 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.utils.company_car import share_of_year_available
+
+
+class company_car_benefit(Variable):
+    value_type = float
+    entity = Person
+    label = "Company car benefit"
+    documentation = (
+        "The cash equivalent of the benefit of the person's company car, "
+        "treated as earnings from their employment (ITEPA 2003 s. 120), "
+        "following the steps of s. 121(1): the price of the car and its "
+        "accessories, less capital contributions up to the cap (s. 132), "
+        "times the appropriate percentage, reduced in proportion to the "
+        "days the car is unavailable (s. 143), less payments for private "
+        "use, and nil if those payments are at least that amount (s. 144). "
+        "Not modelled: optional remuneration arrangements (s. 120A), "
+        "classic cars (s. 147), shared and pool cars (ss. 148 and 167), and "
+        "vans (s. 154 onwards). Calculated from 2020-21."
+    )
+    definition_period = YEAR
+    unit = GBP
+    defined_for = "has_company_car"
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 120",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/120",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 121",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/121",
+        ),
+        dict(
+            title="HMRC 480 Chapter 12: how to work out the benefit of a company car",
+            href="https://www.gov.uk/guidance/how-to-work-out-the-benefit-of-a-company-car-480-chapter-12",
+        ),
+    ]
+
+    def formula_2020(person, period, parameters):
+        p = parameters(period).gov.hmrc.income_tax.benefits_in_kind.company_car
+        # Steps 1 and 2: the price of the car and its accessories.
+        price = max_(person("company_car_list_price", period), 0)
+        # Step 3: capital contributions, up to the cap (s. 132(3)).
+        contributions = min_(
+            max_(person("company_car_capital_contributions", period), 0),
+            p.capital_contribution_cap,
+        )
+        interim_sum = max_(price - contributions, 0)
+        # Steps 5 and 6: the appropriate percentage of the interim sum.
+        full_year = interim_sum * person("company_car_appropriate_percentage", period)
+        # Step 7: s. 143(3) deducts A x U / Y for the days unavailable.
+        provisional_sum = full_year * share_of_year_available(person, period)
+        # Step 8: payments for private use (s. 144).
+        payments = max_(person("company_car_private_use_payments", period), 0)
+        return max_(provisional_sum - payments, 0)
diff --git a/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/has_company_car.py b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/has_company_car.py
new file mode 100644
index 0000000000..fa79a93491
--- /dev/null
+++ b/policyengine_uk/variables/gov/hmrc/income_tax/benefits_in_kind/has_company_car.py
@@ -0,0 +1,21 @@
+from policyengine_uk.model_api import *
+
+
+class has_company_car(Variable):
+    value_type = bool
+    entity = Person
+    label = "Has a company car"
+    documentation = (
+        "Whether the person has a company car available for private use, "
+        "which the model takes from a positive company_car_list_price. The "
+        "appropriate percentage and the company car and car fuel benefits "
+        "are zero without one."
+    )
+    definition_period = YEAR
+    reference = dict(
+        title="Income Tax (Earnings and Pensions) Act 2003 s. 114",
+        href="https://www.legislation.gov.uk/ukpga/2003/1/section/114",
+    )
+
+    def formula(person, period, parameters):
+        return person("company_car_list_price", period) > 0
diff --git a/policyengine_uk/variables/gov/hmrc/national_insurance/class_1a/ni_class_1a.py b/policyengine_uk/variables/gov/hmrc/national_insurance/class_1a/ni_class_1a.py
new file mode 100644
index 0000000000..e66484baf7
--- /dev/null
+++ b/policyengine_uk/variables/gov/hmrc/national_insurance/class_1a/ni_class_1a.py
@@ -0,0 +1,41 @@
+from policyengine_uk.model_api import *
+
+
+class ni_class_1a(Variable):
+    value_type = float
+    entity = Person
+    label = "NI Class 1A contributions"
+    documentation = (
+        "Class 1A contributions the employer pays on the person's taxable "
+        "benefits in kind, which Class 1 leaves out of earnings (SSCBA 1992 "
+        "s. 10(1) and (4)). The Class 1A percentage equals the secondary "
+        "Class 1 percentage for the year (s. 10(5)), except in 2022-23, when "
+        "the Health and Social Care Levy (Repeal) Act 2022 fixes it at "
+        "14.53%. Unlike secondary Class 1, it has no threshold and no zero "
+        "rate for earners under 21 or apprentices under 25, and the "
+        "Employment Allowance cannot be set against it. The employer NI "
+        "incidence variables cover secondary Class 1 only, so no household "
+        "bears Class 1A or a change in it: it stays with the employer as "
+        "revenue in gov_tax."
+    )
+    definition_period = YEAR
+    unit = GBP
+    reference = [
+        dict(
+            title="Social Security Contributions and Benefits Act 1992 s. 10",
+            href="https://www.legislation.gov.uk/ukpga/1992/4/section/10",
+        ),
+        dict(
+            title="Health and Social Care Levy (Repeal) Act 2022 Schedule paragraph 1",
+            href="https://www.legislation.gov.uk/ukpga/2022/43/schedule/paragraph/1/enacted",
+        ),
+    ]
+
+    def formula(person, period, parameters):
+        ni = parameters(period).gov.hmrc.national_insurance
+        fixed = ni.class_1a.percentage_2022_23
+        if fixed.in_effect:
+            rate = fixed.rate
+        else:
+            rate = ni.class_1.employer_scale.components[1].rate
+        return rate * person("benefits_in_kind", period)
diff --git a/policyengine_uk/variables/gov/hmrc/national_insurance/ni_employer.py b/policyengine_uk/variables/gov/hmrc/national_insurance/ni_employer.py
index 063dc1e014..073b87e60e 100644
--- a/policyengine_uk/variables/gov/hmrc/national_insurance/ni_employer.py
+++ b/policyengine_uk/variables/gov/hmrc/national_insurance/ni_employer.py
@@ -5,8 +5,13 @@ class ni_employer(Variable):
     value_type = float
     entity = Person
     label = "employer-side National Insurance"
+    documentation = (
+        "Secondary Class 1 contributions on the person's earnings and Class "
+        "1A contributions on their benefits in kind."
+    )
     definition_period = YEAR
     unit = GBP
     adds = [
         "ni_class_1_employer",
+        "ni_class_1a",
     ]
diff --git a/policyengine_uk/variables/gov/hmrc/national_insurance/total_national_insurance.py b/policyengine_uk/variables/gov/hmrc/national_insurance/total_national_insurance.py
index e972224314..8e28743a1d 100644
--- a/policyengine_uk/variables/gov/hmrc/national_insurance/total_national_insurance.py
+++ b/policyengine_uk/variables/gov/hmrc/national_insurance/total_national_insurance.py
@@ -10,5 +10,5 @@ class total_national_insurance(Variable):
     unit = GBP
     adds = [
         "national_insurance",
-        "ni_class_1_employer",
+        "ni_employer",
     ]
diff --git a/policyengine_uk/variables/gov/hmrc/pensions/pension_contributions_relief.py b/policyengine_uk/variables/gov/hmrc/pensions/pension_contributions_relief.py
index 3ba60f7cd9..a048506d79 100644
--- a/policyengine_uk/variables/gov/hmrc/pensions/pension_contributions_relief.py
+++ b/policyengine_uk/variables/gov/hmrc/pensions/pension_contributions_relief.py
@@ -18,7 +18,8 @@ class pension_contributions_relief(Variable):
         "contributions as relief at source and employee contributions as a "
         "net pay arrangement. The annual allowance does not limit relief. "
         "Relevant UK earnings (s. 189(2)) are employment income, including "
-        "employer-paid taxable statutory pay, less allowable expenses but "
+        "employer-paid taxable statutory pay and taxable benefits in kind, "
+        "less allowable expenses but "
         "before pension deductions, and trading profits after capital "
         "allowances and the trading allowance but before losses. "
         "Contributions above it can be relieved here and separately attract "
diff --git a/policyengine_uk/variables/gov/hmrc/student_loans/plan_2_interest_rate.py b/policyengine_uk/variables/gov/hmrc/student_loans/plan_2_interest_rate.py
index ec5a2f2b5e..709ed627cd 100644
--- a/policyengine_uk/variables/gov/hmrc/student_loans/plan_2_interest_rate.py
+++ b/policyengine_uk/variables/gov/hmrc/student_loans/plan_2_interest_rate.py
@@ -1,4 +1,5 @@
 from policyengine_uk.model_api import *
+from policyengine_uk.utils.student_loans import student_loan_income
 import numpy as np
 
 
@@ -16,7 +17,9 @@ class plan_2_interest_rate(Variable):
     reference = "https://www.legislation.gov.uk/uksi/2012/1309/regulation/10"
 
     def formula(person, period, parameters):
-        income = person("net_income", period)
+        # Interest income is the repayment income (SI 2009/470 reg. 21A(11)),
+        # which leaves out benefits in kind (regs. 29(4)(e) and 41).
+        income = student_loan_income(person, period)
         p = parameters(period).gov.hmrc.student_loans
         rpi = parameters(period).gov.economic_assumptions.yoy_growth.obr.rpi
 
diff --git a/policyengine_uk/variables/gov/hmrc/student_loans/student_loan_repayment.py b/policyengine_uk/variables/gov/hmrc/student_loans/student_loan_repayment.py
index f086a65126..cd24f7df64 100644
--- a/policyengine_uk/variables/gov/hmrc/student_loans/student_loan_repayment.py
+++ b/policyengine_uk/variables/gov/hmrc/student_loans/student_loan_repayment.py
@@ -1,4 +1,5 @@
 from policyengine_uk.model_api import *
+from policyengine_uk.utils.student_loans import student_loan_income
 from policyengine_uk.variables.gov.hmrc.student_loans.student_loan_plan import (
     StudentLoanPlan,
 )
@@ -19,7 +20,8 @@ class student_loan_repayment(Variable):
 
     def formula(person, period, parameters):
         plan = person("student_loan_plan", period)
-        income = person("net_income", period)
+        # Net income less benefits in kind (SI 2009/470 regs. 29(4)(e), 41).
+        income = student_loan_income(person, period)
         balance = max_(0, person("student_loan_balance", period))
         p = parameters(period).gov.hmrc.student_loans
 
diff --git a/policyengine_uk/variables/household/marginal_tax_rate_wrt_employer_cost.py b/policyengine_uk/variables/household/marginal_tax_rate_wrt_employer_cost.py
index 5be93cbc6a..dda3336e72 100644
--- a/policyengine_uk/variables/household/marginal_tax_rate_wrt_employer_cost.py
+++ b/policyengine_uk/variables/household/marginal_tax_rate_wrt_employer_cost.py
@@ -12,8 +12,8 @@ class marginal_tax_rate_wrt_employer_cost(Variable):
     label = "Marginal tax rate with respect to employer cost"
     documentation = (
         "Percent of a marginal increase in the employer's cost of employment "
-        "(gross pay plus employer NI, employer pension contributions and "
-        "statutory sick/maternity/paternity pay) that does not flow to "
+        "(gross pay plus secondary Class 1 NI, employer pension contributions "
+        "and statutory sick/maternity/paternity pay) that does not flow to "
         "household net income. Gross pay rises by "
         "gov.simulation.marginal_tax_rate_delta, or 0.1% of employment income "
         "where that is larger, so that float32 rounding stays negligible at any "
diff --git a/policyengine_uk/variables/input/company_car/company_car_availability.py b/policyengine_uk/variables/input/company_car/company_car_availability.py
new file mode 100644
index 0000000000..f49cd2d09b
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_availability.py
@@ -0,0 +1,28 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_availability(Variable):
+    value_type = float
+    entity = Person
+    label = "Share of the tax year the person's company car is available"
+    documentation = (
+        "The share of the tax year's days on which the company car is "
+        "available to the person: 1 less the share of days on which it is "
+        "unavailable, which are days before it is first available, after it "
+        "is last available, and within a period of 30 days or more when it "
+        "is not available (ITEPA 2003 s. 143(2)). The company car and car "
+        "fuel benefits are reduced in proportion (ss. 143(3) and 152(1))."
+    )
+    definition_period = YEAR
+    unit = "/1"
+    default_value = 1
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 143",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/143",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 152",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/152",
+        ),
+    ]
diff --git a/policyengine_uk/variables/input/company_car/company_car_capital_contributions.py b/policyengine_uk/variables/input/company_car/company_car_capital_contributions.py
new file mode 100644
index 0000000000..bb0b1249a7
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_capital_contributions.py
@@ -0,0 +1,21 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_capital_contributions(Variable):
+    value_type = float
+    entity = Person
+    label = "Capital contributions to the person's company car"
+    documentation = (
+        "Capital sums the person has contributed, in this and earlier tax "
+        "years, to the cost of their company car and its accessories. The "
+        "company car benefit deducts them up to the cap "
+        "(ITEPA 2003 s. 132(3))."
+    )
+    definition_period = YEAR
+    unit = GBP
+    uprating = "gov.economic_assumptions.indices.obr.consumer_price_index"
+    quantity_type = STOCK
+    reference = dict(
+        title="Income Tax (Earnings and Pensions) Act 2003 s. 132",
+        href="https://www.legislation.gov.uk/ukpga/2003/1/section/132",
+    )
diff --git a/policyengine_uk/variables/input/company_car/company_car_co2_emissions.py b/policyengine_uk/variables/input/company_car/company_car_co2_emissions.py
new file mode 100644
index 0000000000..f73a2b76ae
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_co2_emissions.py
@@ -0,0 +1,32 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_co2_emissions(Variable):
+    value_type = float
+    entity = Person
+    label = "CO2 emissions figure of the person's company car"
+    documentation = (
+        "The CO2 emissions figure of the person's company car in grams per "
+        "kilometre, as on its certificate of conformity: 0 for a car that "
+        "cannot emit CO2 by being driven, and taken as 0 for a car of the "
+        "ELECTRIC fuel type. Set it whenever company_car_list_price is set: "
+        "the model cannot tell a missing figure from 0 g/km, and taxes both "
+        "at the zero-emission rate. For a car first registered on or after "
+        "6 April 2020 it is the WLTP figure (ITEPA 2003 s. 136(2B)). "
+        "The model treats every company car as having a CO2 emissions "
+        "figure; cars without one (s. 140) and cars first registered before "
+        "1 January 1998 (s. 142) are not modelled."
+    )
+    definition_period = YEAR
+    unit = "g/km"
+    quantity_type = STOCK
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 136",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/136",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 139",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/139",
+        ),
+    ]
diff --git a/policyengine_uk/variables/input/company_car/company_car_electric_range.py b/policyengine_uk/variables/input/company_car/company_car_electric_range.py
new file mode 100644
index 0000000000..a8c8a0f696
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_electric_range.py
@@ -0,0 +1,20 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_electric_range(Variable):
+    value_type = float
+    entity = Person
+    label = "Electric range figure of the person's company car"
+    documentation = (
+        "The distance in miles the person's company car can be driven in "
+        "electric mode without recharging, as on its certificate of "
+        "conformity (ITEPA 2003 s. 139(5)). Only cars with a CO2 emissions "
+        "figure of 1 to 50 g/km use it, and only to 2027-28."
+    )
+    definition_period = YEAR
+    unit = "mile"
+    quantity_type = STOCK
+    reference = dict(
+        title="Income Tax (Earnings and Pensions) Act 2003 s. 139",
+        href="https://www.legislation.gov.uk/ukpga/2003/1/section/139",
+    )
diff --git a/policyengine_uk/variables/input/company_car/company_car_fuel_type.py b/policyengine_uk/variables/input/company_car/company_car_fuel_type.py
new file mode 100644
index 0000000000..7398bbd5a9
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_fuel_type.py
@@ -0,0 +1,20 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.variables.input.vehicle.car_fuel_type import CarFuelType
+
+
+class company_car_fuel_type(Variable):
+    value_type = Enum
+    possible_values = CarFuelType
+    default_value = CarFuelType.PETROL
+    entity = Person
+    label = "Fuel type of the person's company car"
+    documentation = (
+        "A car propelled solely by diesel that does not meet the Euro 6d "
+        "(RDE2) emissions standard takes the diesel supplement (ITEPA 2003 "
+        "s. 141). A diesel hybrid is not propelled solely by diesel."
+    )
+    definition_period = YEAR
+    reference = dict(
+        title="Income Tax (Earnings and Pensions) Act 2003 s. 141",
+        href="https://www.legislation.gov.uk/ukpga/2003/1/section/141",
+    )
diff --git a/policyengine_uk/variables/input/company_car/company_car_list_price.py b/policyengine_uk/variables/input/company_car/company_car_list_price.py
new file mode 100644
index 0000000000..2661d2a73f
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_list_price.py
@@ -0,0 +1,33 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_list_price(Variable):
+    value_type = float
+    entity = Person
+    label = "List price of the person's company car, with its accessories"
+    documentation = (
+        "The list price of a car made available to the person by reason of "
+        "their employment and for their private use, on the day before its "
+        "first registration, plus the price of its qualifying accessories "
+        "(ITEPA 2003 s. 121(1) steps 1 and 2). Zero means the person has no "
+        "company car. Set company_car_co2_emissions with it: a CO2 figure of "
+        "0 means a car that cannot emit CO2. The benefits it gives must not "
+        "also be in employment_income, or they are taxed twice; a dataset "
+        "whose pay includes benefits in kind, as the SPI's EPB does, must take "
+        "the car and car fuel benefits out of it. This is not car_list_price, "
+        "which describes the person's own car for vehicle excise duty."
+    )
+    definition_period = YEAR
+    unit = GBP
+    uprating = "gov.economic_assumptions.indices.obr.consumer_price_index"
+    quantity_type = STOCK
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 121",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/121",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 123",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/123",
+        ),
+    ]
diff --git a/policyengine_uk/variables/input/company_car/company_car_private_fuel_provided.py b/policyengine_uk/variables/input/company_car/company_car_private_fuel_provided.py
new file mode 100644
index 0000000000..c75c31c2f6
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_private_fuel_provided.py
@@ -0,0 +1,26 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_private_fuel_provided(Variable):
+    value_type = bool
+    entity = Person
+    label = "Fuel provided for private use of the person's company car"
+    documentation = (
+        "Whether fuel is provided for the company car by reason of the "
+        "person's employment and its cost for private use is not made good "
+        "in full (ITEPA 2003 ss. 149 and 151). Electricity is not fuel "
+        "(s. 149(4)). Part-year provision of fuel (s. 152(2)) is not "
+        "modelled; the car fuel benefit is reduced only for days the car is "
+        "unavailable."
+    )
+    definition_period = YEAR
+    reference = [
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 149",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/149",
+        ),
+        dict(
+            title="Income Tax (Earnings and Pensions) Act 2003 s. 151",
+            href="https://www.legislation.gov.uk/ukpga/2003/1/section/151",
+        ),
+    ]
diff --git a/policyengine_uk/variables/input/company_car/company_car_private_use_payments.py b/policyengine_uk/variables/input/company_car/company_car_private_use_payments.py
new file mode 100644
index 0000000000..82b32647a9
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_private_use_payments.py
@@ -0,0 +1,21 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_private_use_payments(Variable):
+    value_type = float
+    entity = Person
+    label = "Payments for private use of the person's company car"
+    documentation = (
+        "Amounts the person is required to pay, and pays by 6 July after the "
+        "tax year, as a condition of the company car being available for "
+        "private use (ITEPA 2003 s. 144). Payments for fuel or insurance are "
+        "not payments for private use."
+    )
+    definition_period = YEAR
+    unit = GBP
+    uprating = "gov.economic_assumptions.indices.obr.consumer_price_index"
+    quantity_type = FLOW
+    reference = dict(
+        title="Income Tax (Earnings and Pensions) Act 2003 s. 144",
+        href="https://www.legislation.gov.uk/ukpga/2003/1/section/144",
+    )
diff --git a/policyengine_uk/variables/input/company_car/company_car_registered_from_6_april_2020.py b/policyengine_uk/variables/input/company_car/company_car_registered_from_6_april_2020.py
new file mode 100644
index 0000000000..7ba9c394e3
--- /dev/null
+++ b/policyengine_uk/variables/input/company_car/company_car_registered_from_6_april_2020.py
@@ -0,0 +1,24 @@
+from policyengine_uk.model_api import *
+
+
+class company_car_registered_from_6_april_2020(Variable):
+    value_type = bool
+    entity = Person
+    label = "Company car first registered on or after 6 April 2020"
+    documentation = (
+        "In 2020-21 and 2021-22 a car first registered on or after 6 April "
+        "2020 has lower appropriate percentages (ITEPA 2003 s. 139A, "
+        "inserted for each year by Finance Act 2020 ss. 9 and 10). From "
+        "2022-23 every car takes the same rates and this has no effect."
+    )
+    definition_period = YEAR
+    reference = [
+        dict(
+            title="Finance Act 2020 s. 9",
+            href="https://www.legislation.gov.uk/ukpga/2020/14/section/9/enacted",
+        ),
+        dict(
+            title="Finance Act 2020 s. 10",
+            href="https://www.legislation.gov.uk/ukpga/2020/14/section/10/enacted",
+        ),
+    ]