MaxGhenis · Oct 31, 2026 · Oct 31, 2026 · Oct 31, 2026 · Oct 31, 2026 · Oct 31, 2026
diff --git a/changelog.d/2738.fixed.md b/changelog.d/2738.fixed.md
@@ -0,0 +1 @@
+Projected the sixteen gambling duty inputs per person from HMRC's 2025-26 receipts and the OBR's October 2026 betting and gaming forecast (receipts Table 4.10), divided by the rates the model charges and by population growth. The inputs no longer stay at their 2024-25 cash level, their weighted totals follow each duty's base as household weights grow with population, and the 2026 and 2027 remote gambling rate rises and the 2027 higher-stake machine rate rise apply once.
diff --git a/docs/engineering/gambling-duties.md b/docs/engineering/gambling-duties.md
diff --git a/policyengine_uk/data/uprating_indices.yaml b/policyengine_uk/data/uprating_indices.yaml
@@ -170,6 +170,33 @@ gov.economic_assumptions.yoy_growth.obr.per_capita.mixed_income:
 - self_employment_gross_receipts
 - trading_loss
 - owned_company_income_share
+# Gambling duty bases grow per person, as household weights grow by
+# population, with the OBR's receipts forecast for their duty divided by the
+# rates the model charges, so the model applies its own rate changes to them
+# once (#2738).
+gov.economic_assumptions.yoy_growth.obr.per_capita.gambling_duty_bases.general_betting:
+- betting_exchange_commission
+- financial_spread_betting_net_losses
+- horse_and_dog_pool_betting_net_losses
+- land_based_fixed_odds_betting_net_losses
+- other_spread_betting_net_losses
+- remote_other_betting_net_losses
+- remote_uk_horseracing_betting_net_losses
+gov.economic_assumptions.yoy_growth.obr.per_capita.gambling_duty_bases.pool_betting:
+- pool_betting_net_receipts
+gov.economic_assumptions.yoy_growth.obr.per_capita.gambling_duty_bases.remote_gaming:
+- remote_gaming_net_losses
+gov.economic_assumptions.yoy_growth.obr.per_capita.gambling_duty_bases.machine_games:
+- machine_games_higher_rate_net_takings
+- machine_games_lower_rate_net_takings
+- machine_games_standard_rate_higher_stake_net_takings
+- machine_games_standard_rate_net_takings
+gov.economic_assumptions.yoy_growth.obr.per_capita.gambling_duty_bases.gaming:
+- land_based_casino_net_losses
+gov.economic_assumptions.yoy_growth.obr.per_capita.gambling_duty_bases.bingo:
+- bingo_net_receipts
+gov.economic_assumptions.yoy_growth.obr.per_capita.gambling_duty_bases.lottery:
+- national_lottery_ticket_spending
 gov.economic_assumptions.yoy_growth.obr.private_pension_index:
 - private_pension_income
 gov.economic_assumptions.yoy_growth.obr.lagged_average_earnings:

diff --git a/policyengine_uk/parameters/gov/economic_assumptions/README.md b/policyengine_uk/parameters/gov/economic_assumptions/README.md
@@ -35,6 +35,7 @@ GDP and population assumptions remain supported.
 | `stamp_duty_land_tax.non_residential` | SDLT receipts from non-residential property  | EFO receipts, property transactions taxes by sector: Table 4.7 in October 2026 |
 | `business_rates.great_britain` | Business rates receipts, England, Scotland and Wales (cash) | EFO receipts, current receipts (cash basis): Table 4.8 in October 2026 |
 | `business_rates.northern_ireland` | Northern Ireland business rates receipts      | EFO receipts, other taxes: Table 4.2 in October 2026 |
+| `per_capita.gambling_duty_bases.<duty>` | The base of each of the seven betting and gaming duties (receipts over the model's rate), per person | HMRC Betting and Gaming tables (2024-25, 2025-26), then EFO receipts, betting and gaming duties forecast breakdown: Table 4.10 in October 2026, over `ons.population` |
 
 The four receipts series project the corporate SDLT and business rates
 statistics (`gov.hmrc.stamp_duty.statistics`,
@@ -45,6 +46,26 @@ in an earlier EFO), the EFO's forecast years, and after them the
 `average_earnings` path. Years before the outturn year are kept, so each
 index keeps its base year.
 
+The seven `per_capita.gambling_duty_bases` series (`general_betting`,
+`pool_betting`, `remote_gaming`, `machine_games`, `gaming`, `bingo`,
+`lottery`) grow the gambling duty inputs (#2738). They grow a duty's base,
+not its receipts: each year's receipts divided by the rate the model charges
+that fiscal year. The model then applies its own rate changes, such as
+Remote Gaming Duty's rise from 21% to 40% on 1 April 2026, once. The OBR
+publishes only forecasts in Table 4.10, so each series starts from HMRC's
+2024-25 receipts, the model's base year, and its 2025-26 outturn, which the
+importer holds in `RECEIPTS_SERIES_SPECS`. The importer holds a base flat in
+any year whose rate is zero, as for Bingo Duty from 2026-27 on, and after the
+forecast it grows every other base with `average_earnings`. The importer
+writes each series per person, (1 +
+base growth) / (1 + `ons.population` growth) - 1 to six decimals, in every
+year to the last that `ons.population` states. Dataset projection grows
+household weights by `ons.population`, so the weighted inputs grow with the
+base. See
+[gambling duties](../../../../docs/engineering/gambling-duties.md#projection)
+for each duty's rates, the higher-stake share Machine Games Duty's rate
+assumes, and the approximations.
+
 `national_living_wage` projects the minimum wage rates
 (`gov.hmrc.minimum_wage`) after the last rate set. It is the growth of the
 rates set to 2027, then the OBR's estimates in Table 1.13 of the detailed
@@ -458,6 +479,16 @@ the forecast levels, though not their growth.
    `policyengine_uk/tests/test_corporate_receipts_statistics.py`
    (`OBR_RECEIPTS_BN`), which pin the series to the OBR's tables. Pass
    `--skip-receipts-growth` only to leave them on the previous EFO.
+   The same run refreshes the `per_capita.gambling_duty_bases` series from
+   the new EFO's betting and gaming duties forecast breakdown and the
+   `ons.population` growth in `yoy_growth.yaml`, so rerun it after any change
+   to that population series. They read no previous EFO: the year before the
+   table's first comes from HMRC's receipts in each spec. When the table starts a year later (2027-28 in October 2027), add
+   HMRC's outturn for the year before from its latest Betting and Gaming
+   tables; the importer stops and names the year until you do. Check the
+   EFO's policy tables for any new measure in the betting and gaming lines.
+   Then update the published levels in
+   `policyengine_uk/tests/test_gambling_duty_base_projection.py`.
 7. If the new EFO runs past `PROJECTION_END_YEAR`, move it on (see
    [Dataset projection horizon](#dataset-projection-horizon)).
 8. Refresh the household energy price inputs (see
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		@@ -0,0 +1 @@
		Projected the sixteen gambling duty inputs per person from HMRC's 2025-26 receipts and the OBR's October 2026 betting and gaming forecast (receipts Table 4.10), divided by the rates the model charges and by population growth. The inputs no longer stay at their 2024-25 cash level, their weighted totals follow each duty's base as household weights grow with population, and the 2026 and 2027 remote gambling rate rises and the 2027 higher-stake machine rate rise apply once.