MaxGhenis · Oct 5, 2026 · Oct 1, 2026 · Oct 1, 2026 · Oct 2, 2026 · Oct 3, 2026
diff --git a/changelog.d/irs-credit-limit-worksheet-order.fixed.md b/changelog.d/irs-credit-limit-worksheet-order.fixed.md
@@ -0,0 +1 @@
+Order the federal non-refundable credits as their IRS credit limit worksheets do: the elderly or disabled credit is limited only by the foreign tax and child and dependent care credits (Schedule R) and precedes the education, retirement savings and energy efficient home improvement credits (Forms 8863, 8880 and 5695); the previously owned clean vehicle credit precedes the new clean vehicle credit (Form 8936) and is now limited by tax; the foreign tax credit applies against tax before 2022; the refundable 2021 child and dependent care credit no longer reduces other credits' limits; and Oklahoma's federal Child Tax Credit applies the credits that Schedule 8812 Credit Limit Worksheet A subtracts before the CTC, not those listed before it.
diff --git a/policyengine_us/parameters/gov/irs/credits/cdcc/preceding_credits.yaml b/policyengine_us/parameters/gov/irs/credits/cdcc/preceding_credits.yaml
@@ -1,12 +1,16 @@
 description: Non-refundable tax credits which precede the Child and Dependent Care Credit.
 values:
+  # Form 2441's Credit Limit Worksheet subtracts Schedule 3 lines 1 (foreign
+  # tax credit) and 6l (Form 8978, not modeled).
   2013-01-01:
-    - foreign_tax_credit 
+    - foreign_tax_credit
 
 metadata:
   unit: list
   period: year
   label: Non-refundable tax credits preceding the CDCC
   reference:
-    - title: IRS Schedule 3, Additional Credits and Payments
-      href: https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
+    - title: 2025 Instructions for Form 2441, Credit Limit Worksheet, line 2
+      href: https://www.irs.gov/pub/irs-pdf/i2441.pdf#page=5
+    - title: 2013 Instructions for Form 2441, Credit Limit Worksheet, line 2
+      href: https://www.irs.gov/pub/irs-prior/i2441--2013.pdf#page=4
diff --git a/policyengine_us/parameters/gov/irs/credits/clean_vehicle/new/preceding_credits.yaml b/policyengine_us/parameters/gov/irs/credits/clean_vehicle/new/preceding_credits.yaml
@@ -1,23 +1,49 @@
 description: Non-refundable tax credits which precede the New Clean Vehicle Credit.
 values:
-  # Section 25D(c) orders the residential clean energy credit after these.
+  # Form 8936 line 11 (line 21 before 2023) subtracts the foreign tax, child
+  # and dependent care, education, retirement savings, energy efficient home
+  # improvement and elderly or disabled credits, Schedule 3 line 6l (Form
+  # 8978, not modeled) and, from 2023, the previously owned clean vehicle
+  # credit (Schedule 3, line 6m). Section 25D(c) orders the residential clean
+  # energy credit after this credit.
   2013-01-01:
     - foreign_tax_credit
     - cdcc
+    - elderly_disabled_credit
     - non_refundable_american_opportunity_credit
     - lifetime_learning_credit
     - savers_credit
     - energy_efficient_home_improvement_credit
+  # The Child and Dependent Care Credit was refundable for 2021 only.
+  2021-01-01:
+    - foreign_tax_credit
+    - elderly_disabled_credit
+    - non_refundable_american_opportunity_credit
+    - lifetime_learning_credit
+    - savers_credit
+    - energy_efficient_home_improvement_credit
+  2022-01-01:
+    - foreign_tax_credit
+    - cdcc
     - elderly_disabled_credit
+    - non_refundable_american_opportunity_credit
+    - lifetime_learning_credit
+    - savers_credit
+    - energy_efficient_home_improvement_credit
+    - used_clean_vehicle_credit
 
 metadata:
   unit: list
   period: year
   label: Non-refundable tax credits preceding the New Clean Vehicle Credit
   reference:
-    - title: IRS Schedule 3, Additional Credits and Payments
-      href: https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
-    - title: 26 U.S. Code § 25D(c) - Carryforward of unused credit
-      href: https://www.law.cornell.edu/uscode/text/26/25D#c
     - title: 2025 Instructions for Form 8936, line 11
       href: https://www.irs.gov/pub/irs-pdf/i8936.pdf#page=6
+    - title: 2023 Instructions for Form 8936, line 11
+      href: https://www.irs.gov/pub/irs-prior/i8936--2023.pdf#page=5
+    - title: 2022 Instructions for Form 8936, line 21
+      href: https://www.irs.gov/pub/irs-prior/i8936--2022.pdf#page=3
+    - title: 2017 Instructions for Form 8936, line 21
+      href: https://www.irs.gov/pub/irs-prior/i8936--2017.pdf#page=2
+    - title: 26 U.S. Code § 25D(c) - Carryforward of unused credit
+      href: https://www.law.cornell.edu/uscode/text/26/25D#c
diff --git a/policyengine_us/parameters/gov/irs/credits/clean_vehicle/used/preceding_credits.yaml b/policyengine_us/parameters/gov/irs/credits/clean_vehicle/used/preceding_credits.yaml
@@ -1,24 +1,44 @@
 description: Non-refundable tax credits which precede the Used Clean Vehicle Credit.
 values:
-  # Section 25D(c) orders the residential clean energy credit after these.
+  # Form 8936 line 16 subtracts Schedule 3 lines 1 through 4 (foreign tax,
+  # child and dependent care, education and retirement savings credits), 5b
+  # (energy efficient home improvement credit), 6d (elderly or disabled
+  # credit) and 6l (Form 8978, not modeled). It does not subtract line 6f, so
+  # this credit precedes the new clean vehicle credit. Section 25D(c) orders
+  # the residential clean energy credit after this credit.
   2013-01-01:
     - foreign_tax_credit
     - cdcc
+    - elderly_disabled_credit
     - non_refundable_american_opportunity_credit
     - lifetime_learning_credit
     - savers_credit
     - energy_efficient_home_improvement_credit
+  # The Child and Dependent Care Credit was refundable for 2021 only.
+  2021-01-01:
+    - foreign_tax_credit
+    - elderly_disabled_credit
+    - non_refundable_american_opportunity_credit
+    - lifetime_learning_credit
+    - savers_credit
+    - energy_efficient_home_improvement_credit
+  2022-01-01:
+    - foreign_tax_credit
+    - cdcc
     - elderly_disabled_credit
-    - new_clean_vehicle_credit
+    - non_refundable_american_opportunity_credit
+    - lifetime_learning_credit
+    - savers_credit
+    - energy_efficient_home_improvement_credit
 
 metadata:
   unit: list
   period: year
   label: Non-refundable tax credits preceding the Used Clean Vehicle Credit
   reference:
-    - title: IRS Schedule 3, Additional Credits and Payments
-      href: https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
-    - title: 26 U.S. Code § 25D(c) - Carryforward of unused credit
-      href: https://www.law.cornell.edu/uscode/text/26/25D#c
     - title: 2025 Instructions for Form 8936, line 16
       href: https://www.irs.gov/pub/irs-pdf/i8936.pdf#page=6
+    - title: 2023 Instructions for Form 8936, line 16
+      href: https://www.irs.gov/pub/irs-prior/i8936--2023.pdf#page=5
+    - title: 26 U.S. Code § 25D(c) - Carryforward of unused credit
+      href: https://www.law.cornell.edu/uscode/text/26/25D#c
diff --git a/policyengine_us/parameters/gov/irs/credits/ctc_tax_liability_limit/preceding_credits.yaml b/policyengine_us/parameters/gov/irs/credits/ctc_tax_liability_limit/preceding_credits.yaml
@@ -1,21 +1,23 @@
 description: The IRS subtracts these non-refundable credits from income tax before credits to find the tax liability that limits the non-refundable Child Tax Credit.
 values:
-  # The foreign tax credit also precedes the CTC before 2022, but the model
-  # applies it against regular tax only from 2022 (see non_refundable.yaml).
+  # Before 2021 the new clean vehicle credit is not modeled; Publication 972
+  # also subtracted it (Form 8936, line 23).
   2013-01-01:
+    - foreign_tax_credit
     - cdcc
+    - elderly_disabled_credit
     - non_refundable_american_opportunity_credit
     - lifetime_learning_credit
     - savers_credit
     - energy_efficient_home_improvement_credit
-    - elderly_disabled_credit
   # The Child and Dependent Care Credit was refundable for 2021 only.
   2021-01-01:
+    - foreign_tax_credit
+    - elderly_disabled_credit
     - non_refundable_american_opportunity_credit
     - lifetime_learning_credit
     - savers_credit
     - energy_efficient_home_improvement_credit
-    - elderly_disabled_credit
     - new_clean_vehicle_credit
   # Line numbers are those of the 2023-2025 Schedule 3. In 2022 the energy
   # efficient home improvement credit came from Form 5695, line 30, and the
@@ -25,13 +27,13 @@ values:
   2022-01-01:
     - foreign_tax_credit # Schedule 3, line 1
     - cdcc # Schedule 3, line 2
+    - elderly_disabled_credit # Schedule 3, line 6d
     - non_refundable_american_opportunity_credit # Schedule 3, line 3
     - lifetime_learning_credit # Schedule 3, line 3
     - savers_credit # Schedule 3, line 4
     - energy_efficient_home_improvement_credit # Schedule 3, line 5b
-    - elderly_disabled_credit # Schedule 3, line 6d
-    - new_clean_vehicle_credit # Schedule 3, line 6f
     - used_clean_vehicle_credit # Schedule 3, line 6m
+    - new_clean_vehicle_credit # Schedule 3, line 6f
   # The residential clean energy credit (Schedule 3, line 5a) is not listed:
   # section 25D(c) orders it after every other credit in subpart A, including
   # the Child Tax Credit. See subsequent_credits.yaml for the case in which it
@@ -48,6 +50,8 @@ metadata:
       href: https://www.irs.gov/pub/irs-prior/i1040s8--2022.pdf#page=4
     - title: 2020 Publication 972, Child Tax Credit and Credit for Other Dependents Worksheet, line 12
       href: https://www.irs.gov/pub/irs-prior/p972--2020.pdf#page=7
+    - title: 2013 Publication 972, Child Tax Credit Worksheet, line 10
+      href: https://www.irs.gov/pub/irs-prior/p972--2013.pdf#page=5
     - title: 26 U.S. Code § 26(a) - Limitation based on amount of tax
       href: https://www.law.cornell.edu/uscode/text/26/26#a
     - title: 26 U.S. Code § 25D(c) - Carryforward of unused credit

diff --git a/...s/parameters/gov/irs/credits/education/american_opportunity_credit/preceding_credits.yaml b/...s/parameters/gov/irs/credits/education/american_opportunity_credit/preceding_credits.yaml
@@ -1,13 +1,31 @@
 description: Non-refundable tax credits which precede the American Opportunity Credit.
 values:
+  # Form 8863's Credit Limit Worksheet subtracts Schedule 3 lines 1 (foreign
+  # tax credit), 2 (child and dependent care credit), 6d (elderly or disabled
+  # credit) and 6l (Form 8978, not modeled).
   2013-01-01:
-    - foreign_tax_credit 
+    - foreign_tax_credit
     - cdcc
+    - elderly_disabled_credit
+  # The Child and Dependent Care Credit was refundable for 2021 only.
+  2021-01-01:
+    - foreign_tax_credit
+    - elderly_disabled_credit
+  2022-01-01:
+    - foreign_tax_credit
+    - cdcc
+    - elderly_disabled_credit
 
 metadata:
   unit: list
   period: year
   label: Non-refundable tax credits preceding the American Opportunity Credit
   reference:
-    - title: IRS Schedule 3, Additional Credits and Payments
-      href: https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
+    - title: 2025 Instructions for Form 8863, Credit Limit Worksheet, line 5
+      href: https://www.irs.gov/pub/irs-pdf/i8863.pdf#page=8
+    - title: 2021 Instructions for Form 8863, Credit Limit Worksheet, line 5
+      href: https://www.irs.gov/pub/irs-prior/i8863--2021.pdf#page=7
+    - title: 2013 Instructions for Form 8863, Credit Limit Worksheet, line 5
+      href: https://www.irs.gov/pub/irs-prior/i8863--2013.pdf#page=6
+    - title: 26 U.S. Code § 21(g) - Special rules for 2021
+      href: https://www.law.cornell.edu/uscode/text/26/21#g
diff --git a/...e_us/parameters/gov/irs/credits/education/lifetime_learning_credit/preceding_credits.yaml b/...e_us/parameters/gov/irs/credits/education/lifetime_learning_credit/preceding_credits.yaml
@@ -1,14 +1,35 @@
 description: Non-refundable tax credits which precede the Lifetime Learning Credit.
 values:
+  # Form 8863's Credit Limit Worksheet limits the non-refundable American
+  # opportunity and lifetime learning credits together (lines 1 to 3) to tax
+  # less Schedule 3 lines 1, 2, 6d and 6l. Applying the American opportunity
+  # credit first gives the same total.
   2013-01-01:
-    - foreign_tax_credit 
+    - foreign_tax_credit
     - cdcc
+    - elderly_disabled_credit
+    - non_refundable_american_opportunity_credit
+  # The Child and Dependent Care Credit was refundable for 2021 only.
+  2021-01-01:
+    - foreign_tax_credit
+    - elderly_disabled_credit
+    - non_refundable_american_opportunity_credit
+  2022-01-01:
+    - foreign_tax_credit
+    - cdcc
+    - elderly_disabled_credit
     - non_refundable_american_opportunity_credit
 
 metadata:
   unit: list
   period: year
   label: Non-refundable tax credits preceding the Lifetime Learning Credit
   reference:
-    - title: IRS Schedule 3, Additional Credits and Payments
-      href: https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
+    - title: 2025 Instructions for Form 8863, Credit Limit Worksheet, lines 1 to 7
+      href: https://www.irs.gov/pub/irs-pdf/i8863.pdf#page=8
+    - title: 2021 Instructions for Form 8863, Credit Limit Worksheet, lines 1 to 7
+      href: https://www.irs.gov/pub/irs-prior/i8863--2021.pdf#page=7
+    - title: 2013 Instructions for Form 8863, Credit Limit Worksheet, lines 1 to 7
+      href: https://www.irs.gov/pub/irs-prior/i8863--2013.pdf#page=6
+    - title: 26 U.S. Code § 21(g) - Special rules for 2021
+      href: https://www.law.cornell.edu/uscode/text/26/21#g
diff --git a/policyengine_us/parameters/gov/irs/credits/elderly_or_disabled/preceding_credits.yaml b/policyengine_us/parameters/gov/irs/credits/elderly_or_disabled/preceding_credits.yaml
@@ -1,22 +1,29 @@
 description: Non-refundable tax credits which precede the Elderly or Disabled Credit.
 values:
-  # Section 25D(c) orders the residential clean energy credit after these.
+  # Schedule R's Credit Limit Worksheet subtracts only Schedule 3 lines 1
+  # (foreign tax credit), 2 (child and dependent care credit) and 6l (Form
+  # 8978, not modeled). The education, retirement savings, energy and clean
+  # vehicle credits come after this credit.
   2013-01-01:
     - foreign_tax_credit
     - cdcc
-    - non_refundable_american_opportunity_credit
-    - lifetime_learning_credit
-    - savers_credit
-    - energy_efficient_home_improvement_credit
+  # The Child and Dependent Care Credit was refundable for 2021 only.
+  2021-01-01:
+    - foreign_tax_credit
+  2022-01-01:
+    - foreign_tax_credit
+    - cdcc
 
 metadata:
   unit: list
   period: year
   label: Non-refundable tax credits preceding the Elderly or Disabled Credit
   reference:
-    - title: IRS Schedule 3, Additional Credits and Payments
-      href: https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
-    - title: 26 U.S. Code § 25D(c) - Carryforward of unused credit
-      href: https://www.law.cornell.edu/uscode/text/26/25D#c
     - title: 2025 Instructions for Schedule R (Form 1040), Credit Limit Worksheet, line 2
       href: https://www.irs.gov/pub/irs-pdf/i1040sr.pdf#page=4
+    - title: 2021 Instructions for Schedule R (Form 1040), Credit Limit Worksheet—Line 21, line 2
+      href: https://www.irs.gov/pub/irs-prior/i1040sr--2021.pdf#page=3
+    - title: 2013 Instructions for Schedule R (Form 1040A or 1040), Credit Limit Worksheet—Line 21, line 2
+      href: https://www.irs.gov/pub/irs-prior/i1040sr--2013.pdf#page=3
+    - title: 26 U.S. Code § 21(g) - Special rules for 2021
+      href: https://www.law.cornell.edu/uscode/text/26/21#g
diff --git a/...ne_us/parameters/gov/irs/credits/energy_efficient_home_improvement/preceding_credits.yaml b/...ne_us/parameters/gov/irs/credits/energy_efficient_home_improvement/preceding_credits.yaml
@@ -1,9 +1,29 @@
 description: Non-refundable tax credits which precede the Energy Efficient Home Improvement Credit.
 values:
-  # Section 25D(c) orders the residential clean energy credit after these.
+  # Form 5695's Energy Efficient Home Improvement Credit Limit Worksheet (the
+  # Nonbusiness Energy Property Credit Limit Worksheet before 2022) subtracts
+  # the foreign tax, child and dependent care, elderly or disabled, education
+  # and retirement savings credits, and Schedule 3 line 6l (Form 8978, not
+  # modeled). Section 25D(c) orders the residential clean energy credit after
+  # this credit.
   2013-01-01:
     - foreign_tax_credit
     - cdcc
+    - elderly_disabled_credit
+    - non_refundable_american_opportunity_credit
+    - lifetime_learning_credit
+    - savers_credit
+  # The Child and Dependent Care Credit was refundable for 2021 only.
+  2021-01-01:
+    - foreign_tax_credit
+    - elderly_disabled_credit
+    - non_refundable_american_opportunity_credit
+    - lifetime_learning_credit
+    - savers_credit
+  2022-01-01:
+    - foreign_tax_credit
+    - cdcc
+    - elderly_disabled_credit
     - non_refundable_american_opportunity_credit
     - lifetime_learning_credit
     - savers_credit
@@ -13,9 +33,13 @@ metadata:
   period: year
   label: Non-refundable tax credits preceding the Energy Efficient Home Improvement Credit
   reference:
-    - title: IRS Schedule 3, Additional Credits and Payments
-      href: https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
+    - title: 2025 Instructions for Form 5695, Energy Efficient Home Improvement Credit Limit Worksheet—Line 31, line 2
+      href: https://www.irs.gov/pub/irs-pdf/i5695.pdf#page=7
+    - title: 2022 Instructions for Form 5695, Energy Efficient Home Improvement Credit Limit Worksheet—Line 29, line 2
+      href: https://www.irs.gov/pub/irs-prior/i5695--2022.pdf#page=7
+    - title: 2013 Form 5695, Nonbusiness Energy Property Credit Limit Worksheet—Line 29, line 2
+      href: https://www.irs.gov/pub/irs-prior/f5695--2013.pdf#page=6
     - title: 26 U.S. Code § 25D(c) - Carryforward of unused credit
       href: https://www.law.cornell.edu/uscode/text/26/25D#c
-    - title: 2025 Instructions for Form 5695, Energy Efficient Home Improvement Credit Limit Worksheet, line 2
-      href: https://www.irs.gov/pub/irs-pdf/i5695.pdf#page=7
+    - title: 26 U.S. Code § 21(g) - Special rules for 2021
+      href: https://www.law.cornell.edu/uscode/text/26/21#g
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Order the federal non-refundable credits as their IRS credit limit worksheets do: the elderly or disabled credit is limited only by the foreign tax and child and dependent care credits (Schedule R) and precedes the education, retirement savings and energy efficient home improvement credits (Forms 8863, 8880 and 5695); the previously owned clean vehicle credit precedes the new clean vehicle credit (Form 8936) and is now limited by tax; the foreign tax credit applies against tax before 2022; the refundable 2021 child and dependent care credit no longer reduces other credits' limits; and Oklahoma's federal Child Tax Credit applies the credits that Schedule 8812 Credit Limit Worksheet A subtracts before the CTC, not those listed before it.