From 1b5112518e34769471d3df18164378c776f5738e Mon Sep 17 00:00:00 2001
From: Max Ghenis <max@policyengine.org>
Date: Fri, 25 Sep 2026 07:20:53 -0400
Subject: [PATCH 1/3] Fix Arkansas 2025 and 2024 minus-adjustment schedules
 against DFA cards

2025: the reduction scale jumped from the $26,400 row ($420) straight to
$95,001, skipping DFA's $94,701-$94,800 ($399.30), $94,801-$94,900
($389.30) and $94,901-$95,000 ($379.30) rows, so taxable income in that
band was undertaxed by $20.70-$40.70. The column also carried rounded
amounts (112/224/288/420, 369...89) instead of DFA's published cents
(111.98/223.97/287.97/419.96, 369.30...89.30). Re-keyed the whole 2025
column to the 2025 Indexed Tax Brackets card; its rows now line up with
the 2026 Act 1 rows, and the two newly finite 2025 rows keep their
explicit 2026 .inf, so 2026 is unchanged.

2024: the column ignored the card's asterisked $94,301-$94,500 row,
so $94,401-$95,500 each took the next $10 step down ($10 overtax).

Verified every integer taxable income 0-110,000 for 2021-2025 against
the DFA TaxBrackets cards and 2026 against Act 1 of 2026: 0 mismatches
(upstream/main: 1,100 in 2024, 104,403 in 2025). Loaded rate and
reduction scales for 2015-2035 are otherwise identical.

Also points the 2025 booklet reference at the Regular Income Tax Table
(PDF page 30; #page=26 was the printed page number) and cites the 2025
TaxBrackets card in rate.yaml and reduction.yaml.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../fix-ar-2025-reduction-schedule.fixed.md   |   1 +
 .../states/ar/tax/income/rates/main/rate.yaml |   6 +-
 .../ar/tax/income/rates/main/reduction.yaml   | 198 ++++++++--------
 ...x_before_non_refundable_credits_indiv.yaml | 219 +++++++++++++++++-
 ...x_before_non_refundable_credits_joint.yaml |  10 +-
 5 files changed, 317 insertions(+), 117 deletions(-)
 create mode 100644 changelog.d/fix-ar-2025-reduction-schedule.fixed.md

diff --git a/changelog.d/fix-ar-2025-reduction-schedule.fixed.md b/changelog.d/fix-ar-2025-reduction-schedule.fixed.md
new file mode 100644
index 00000000000..fc3becccd2d
--- /dev/null
+++ b/changelog.d/fix-ar-2025-reduction-schedule.fixed.md
@@ -0,0 +1 @@
+Fix Arkansas 2025 and 2024 income tax minus-adjustment schedules to match the DFA Indexed Tax Brackets: add the missing 2025 $94,701-$95,000 rows (previously taxed with the $419.96 adjustment), use DFA's exact cents for 2025, and honor the 2024 asterisked $94,301-$94,500 row.
diff --git a/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/rate.yaml b/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/rate.yaml
index b90beb0ff0a..2ad57034002 100644
--- a/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/rate.yaml
+++ b/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/rate.yaml
@@ -26,8 +26,10 @@ metadata:
     href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxBrackets_2023.pdf#page=1
   - title: 2024 Indexed Tax Brackets
     href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_TaxBrackets.pdf#page=1
-  - title: Arkansas 2025 Individual Income Tax Forms and Instructions
-    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_AR1000F_and_AR1000NR_Instructions.pdf#page=26
+  - title: 2025 Indexed Tax Brackets
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_TaxBrackets.pdf#page=1
+  - title: Arkansas 2025 Individual Income Tax Forms and Instructions (2025 Regular Income Tax Table)
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_AR1000F_and_AR1000NR_Instructions.pdf#page=30
   - title: Arkansas Act 1 of 2026 (HB1001, 1st Extraordinary Session), Section 1 amending A.C.A. § 26-51-201(a)(4)
     href: https://www.arkleg.state.ar.us/Home/FTPDocument?path=%2FBills%2F2026S1%2FPublic%2FHB1001.pdf#page=2
   - title: Arkansas Legislature HB1001 status page (enacted as Act 1, 2026 1st Extraordinary Session)
diff --git a/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/reduction.yaml b/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/reduction.yaml
index 3a25a6b4f85..17187b1d993 100644
--- a/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/reduction.yaml
+++ b/policyengine_us/parameters/gov/states/ar/tax/income/rates/main/reduction.yaml
@@ -15,8 +15,10 @@ metadata:
     href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxBrackets_2023.pdf#page=1
   - title: 2024 Indexed Tax Brackets
     href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_TaxBrackets.pdf#page=1
-  - title: Arkansas 2025 Individual Income Tax Forms and Instructions
-    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_AR1000F_and_AR1000NR_Instructions.pdf#page=26
+  - title: 2025 Indexed Tax Brackets
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_TaxBrackets.pdf#page=1
+  - title: Arkansas 2025 Individual Income Tax Forms and Instructions (2025 Regular Income Tax Table)
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_AR1000F_and_AR1000NR_Instructions.pdf#page=30
   - title: Arkansas Act 1 of 2026 (HB1001, 1st Extraordinary Session), Section 1 amending A.C.A. § 26-51-201(a)(4)(C)
     href: https://www.arkleg.state.ar.us/Home/FTPDocument?path=%2FBills%2F2026S1%2FPublic%2FHB1001.pdf#page=2
   - title: Arkansas Legislature HB1001 status page (enacted as Act 1, 2026 1st Extraordinary Session)
@@ -40,7 +42,7 @@ brackets:
       2022-01-01: 101.98
       2023-01-01: 105.98
       2024-01-01: 109.98
-      2025-01-01: 112
+      2025-01-01: 111.98
       2026-01-01: 112
   - threshold:
       2021-01-01: 9_500
@@ -54,7 +56,7 @@ brackets:
       2022-01-01: 204.97
       2023-01-01: 211.97
       2024-01-01: 218.97
-      2025-01-01: 224
+      2025-01-01: 223.97
       2026-01-01: 224
   - threshold:
       2021-01-01: 14_300
@@ -68,7 +70,7 @@ brackets:
       2022-01-01: 263.77
       2023-01-01: 272.37
       2024-01-01: 281.37
-      2025-01-01: 288
+      2025-01-01: 287.97
       2026-01-01: 288
   - threshold:
       2021-01-01: 23_600
@@ -82,461 +84,461 @@ brackets:
       2022-01-01: 628.25
       2023-01-01: 597.35
       2024-01-01: 409.86
-      2025-01-01: 420
+      2025-01-01: 419.96
       2026-01-01: 367.20
   - threshold:
       2021-01-01: 39_700
       2022-01-01: 87_001
       2023-01-01: 89_601
       2024-01-01: 92_301
-      2025-01-01: 95_001
+      2025-01-01: 94_701
       2026-01-01: 94_701
     amount:
       2021-01-01: 797.25
       2022-01-01: 627.20
       2023-01-01: 583.7
       2024-01-01: 397.40
-      2025-01-01: 369
+      2025-01-01: 399.30
       2026-01-01: 369.90
   - threshold:
       2021-01-01: 84_501
       2022-01-01: 87_101
       2023-01-01: 89_701
       2024-01-01: 92_401
-      2025-01-01: 95_101
+      2025-01-01: 94_801
       2026-01-01: 94_801
     amount:
       2021-01-01: 687.5
       2022-01-01: 617.20
       2023-01-01: 573.7
       2024-01-01: 387.40
-      2025-01-01: 359
+      2025-01-01: 389.30
       2026-01-01: 359.90
   - threshold:
       2021-01-01: 85_501
       2022-01-01: 87_201
       2023-01-01: 89_801
       2024-01-01: 92_501
-      2025-01-01: 95_201
+      2025-01-01: 94_901
       2026-01-01: 94_901
     amount:
       2021-01-01: 587.5
       2022-01-01: 607.20
       2023-01-01: 563.7
       2024-01-01: 377.40
-      2025-01-01: 349
+      2025-01-01: 379.30
       2026-01-01: 349.90
   - threshold:
       2021-01-01: 86_501
       2022-01-01: 87_301
       2023-01-01: 89_901
       2024-01-01: 92_601
-      2025-01-01: 95_301
+      2025-01-01: 95_001
       2026-01-01: 95_001
     amount:
       2021-01-01: 487.5
       2022-01-01: 597.20
       2023-01-01: 553.7
       2024-01-01: 367.40
-      2025-01-01: 339
+      2025-01-01: 369.30
       2026-01-01: 339.90
   - threshold:
       2021-01-01: 87_901
       2022-01-01: 87_401
       2023-01-01: 90_001
       2024-01-01: 92_701
-      2025-01-01: 95_401
+      2025-01-01: 95_101
       2026-01-01: 95_101
     amount:
       2021-01-01: 387.5
       2022-01-01: 587.20
       2023-01-01: 543.7
       2024-01-01: 357.40
-      2025-01-01: 329
+      2025-01-01: 359.30
       2026-01-01: 329.90
   - threshold:
       2021-01-01: 89_001
       2022-01-01: 87_601
       2023-01-01: 90_201
       2024-01-01: 92_801
-      2025-01-01: 95_501
+      2025-01-01: 95_201
       2026-01-01: 95_201
     amount:
       2021-01-01: 287.5
       2022-01-01: 577.20
       2023-01-01: 533.7
       2024-01-01: 347.40
-      2025-01-01: 319
+      2025-01-01: 349.30
       2026-01-01: 319.90
   - threshold:
       2021-01-01: 90_101
       2022-01-01: 87_701
       2023-01-01: 90_301
       2024-01-01: 92_901
-      2025-01-01: 95_601
+      2025-01-01: 95_301
       2026-01-01: 95_301
     amount:
       2021-01-01: 247.5
       2022-01-01: 567.20
       2023-01-01: 523.7
       2024-01-01: 337.40
-      2025-01-01: 309
+      2025-01-01: 339.30
       2026-01-01: 309.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 87_801
       2023-01-01: 90_401
       2024-01-01: 93_001
-      2025-01-01: 95_701
+      2025-01-01: 95_401
       2026-01-01: 95_401
     amount:
       2021-01-01: 247.5
       2022-01-01: 557.20
       2023-01-01: 513.7
       2024-01-01: 327.40
-      2025-01-01: 299
+      2025-01-01: 329.30
       2026-01-01: 299.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 87_901
       2023-01-01: 90_501
       2024-01-01: 93_101
-      2025-01-01: 95_801
+      2025-01-01: 95_501
       2026-01-01: 95_501
     amount:
       2021-01-01: 247.5
       2022-01-01: 547.20
       2023-01-01: 503.7
       2024-01-01: 317.40
-      2025-01-01: 289
+      2025-01-01: 319.30
       2026-01-01: 289.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_001
       2023-01-01: 90_601
       2024-01-01: 93_201
-      2025-01-01: 95_901
+      2025-01-01: 95_601
       2026-01-01: 95_601
     amount:
       2021-01-01: 247.5
       2022-01-01: 537.20
       2023-01-01: 493.7
       2024-01-01: 307.40
-      2025-01-01: 279
+      2025-01-01: 309.30
       2026-01-01: 279.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_101
       2023-01-01: 90_701
       2024-01-01: 93_301
-      2025-01-01: 96_001
+      2025-01-01: 95_701
       2026-01-01: 95_701
     amount:
       2021-01-01: 247.5
       2022-01-01: 527.20
       2023-01-01: 483.7
       2024-01-01: 297.40
-      2025-01-01: 269
+      2025-01-01: 299.30
       2026-01-01: 269.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_201
       2023-01-01: 90_801
       2024-01-01: 93_401
-      2025-01-01: 96_101
+      2025-01-01: 95_801
       2026-01-01: 95_801
     amount:
       2021-01-01: 247.5
       2022-01-01: 517.20
       2023-01-01: 473.7
       2024-01-01: 287.40
-      2025-01-01: 259
+      2025-01-01: 289.30
       2026-01-01: 259.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_301
       2023-01-01: 90_901
       2024-01-01: 93_501
-      2025-01-01: 96_201
+      2025-01-01: 95_901
       2026-01-01: 95_901
     amount:
       2021-01-01: 247.5
       2022-01-01: 507.20
       2023-01-01: 463.7
       2024-01-01: 277.40
-      2025-01-01: 249
+      2025-01-01: 279.30
       2026-01-01: 249.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_401
       2023-01-01: 91_101
       2024-01-01: 93_601
-      2025-01-01: 96_301
+      2025-01-01: 96_001
       2026-01-01: 96_001
     amount:
       2021-01-01: 247.5
       2022-01-01: 497.20
       2023-01-01: 453.7
       2024-01-01: 267.40
-      2025-01-01: 239
+      2025-01-01: 269.30
       2026-01-01: 239.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_501
       2023-01-01: 91_201
       2024-01-01: 93_701
-      2025-01-01: 96_401
+      2025-01-01: 96_101
       2026-01-01: 96_101
     amount:
       2021-01-01: 247.5
       2022-01-01: 487.20
       2023-01-01: 443.7
       2024-01-01: 257.40
-      2025-01-01: 229
+      2025-01-01: 259.30
       2026-01-01: 229.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_601
       2023-01-01: 91_301
       2024-01-01: 93_801
-      2025-01-01: 96_501
+      2025-01-01: 96_201
       2026-01-01: 96_201
     amount:
       2021-01-01: 247.5
       2022-01-01: 477.20
       2023-01-01: 433.7
       2024-01-01: 247.40
-      2025-01-01: 219
+      2025-01-01: 249.30
       2026-01-01: 219.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_701
       2023-01-01: 91_401
       2024-01-01: 93_901
-      2025-01-01: 96_601
+      2025-01-01: 96_301
       2026-01-01: 96_301
     amount:
       2021-01-01: 247.5
       2022-01-01: 467.20
       2023-01-01: 423.7
       2024-01-01: 237.40
-      2025-01-01: 209
+      2025-01-01: 239.30
       2026-01-01: 209.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_801
       2023-01-01: 91_501
       2024-01-01: 94_001
-      2025-01-01: 96_701
+      2025-01-01: 96_401
       2026-01-01: 96_401
     amount:
       2021-01-01: 247.5
       2022-01-01: 457.20
       2023-01-01: 413.7
       2024-01-01: 227.40
-      2025-01-01: 199
+      2025-01-01: 229.30
       2026-01-01: 199.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_901
       2023-01-01: 91_601
       2024-01-01: 94_101
-      2025-01-01: 96_801
+      2025-01-01: 96_501
       2026-01-01: 96_501
     amount:
       2021-01-01: 247.5
       2022-01-01: 447.20
       2023-01-01: 403.7
       2024-01-01: 217.40
-      2025-01-01: 189
+      2025-01-01: 219.30
       2026-01-01: 189.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_001
       2023-01-01: 91_701
       2024-01-01: 94_201
-      2025-01-01: 96_901
+      2025-01-01: 96_601
       2026-01-01: 96_601
     amount:
       2021-01-01: 247.5
       2022-01-01: 437.20
       2023-01-01: 393.7
       2024-01-01: 207.40
-      2025-01-01: 179
+      2025-01-01: 209.30
       2026-01-01: 179.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_101
       2023-01-01: 91_801
       2024-01-01: 94_301
-      2025-01-01: 97_001
+      2025-01-01: 96_701
       2026-01-01: 96_701
     amount:
       2021-01-01: 247.5
       2022-01-01: 427.20
       2023-01-01: 383.7
       2024-01-01: 197.40
-      2025-01-01: 169
+      2025-01-01: 199.30
       2026-01-01: 169.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_201
       2023-01-01: 91_901
-      2024-01-01: 94_401
-      2025-01-01: 97_101
+      2024-01-01: 94_501
+      2025-01-01: 96_801
       2026-01-01: 96_801
     amount:
       2021-01-01: 247.5
       2022-01-01: 417.20
       2023-01-01: 373.7
       2024-01-01: 187.40
-      2025-01-01: 159
+      2025-01-01: 189.30
       2026-01-01: 159.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_301
       2023-01-01: 92_001
-      2024-01-01: 94_501
-      2025-01-01: 97_201
+      2024-01-01: 94_601
+      2025-01-01: 96_901
       2026-01-01: 96_901
     amount:
       2021-01-01: 247.5
       2022-01-01: 407.20
       2023-01-01: 363.7
       2024-01-01: 177.40
-      2025-01-01: 149
+      2025-01-01: 179.30
       2026-01-01: 149.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_401
       2023-01-01: 92_101
-      2024-01-01: 94_601
-      2025-01-01: 97_301
+      2024-01-01: 94_701
+      2025-01-01: 97_001
       2026-01-01: 97_001
     amount:
       2021-01-01: 247.5
       2022-01-01: 397.20
       2023-01-01: 353.7
       2024-01-01: 167.40
-      2025-01-01: 139
+      2025-01-01: 169.30
       2026-01-01: 139.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_501
       2023-01-01: 92_201
-      2024-01-01: 94_701
-      2025-01-01: 97_401
+      2024-01-01: 94_801
+      2025-01-01: 97_101
       2026-01-01: 97_101
     amount:
       2021-01-01: 247.5
       2022-01-01: 387.20
       2023-01-01: 343.7
       2024-01-01: 157.40
-      2025-01-01: 129
+      2025-01-01: 159.30
       2026-01-01: 129.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_601
       2023-01-01: 92_301
-      2024-01-01: 94_801
-      2025-01-01: 97_501
+      2024-01-01: 94_901
+      2025-01-01: 97_201
       2026-01-01: 97_201
     amount:
       2021-01-01: 247.5
       2022-01-01: 377.20
       2023-01-01: 333.7
       2024-01-01: 147.40
-      2025-01-01: 119
+      2025-01-01: 149.30
       2026-01-01: 119.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_701
       2023-01-01: 92_401
-      2024-01-01: 94_901
-      2025-01-01: 97_601
+      2024-01-01: 95_001
+      2025-01-01: 97_301
       2026-01-01: 97_301
     amount:
       2021-01-01: 247.5
       2022-01-01: 367.20
       2023-01-01: 323.7
       2024-01-01: 137.40
-      2025-01-01: 109
+      2025-01-01: 139.30
       2026-01-01: 109.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_801
       2023-01-01: 92_501
-      2024-01-01: 95_001
-      2025-01-01: 97_701
+      2024-01-01: 95_101
+      2025-01-01: 97_401
       2026-01-01: 97_401
     amount:
       2021-01-01: 247.5
       2022-01-01: 357.20
       2023-01-01: 313.7
       2024-01-01: 127.40
-      2025-01-01: 99
+      2025-01-01: 129.30
       2026-01-01: 99.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_901
       2023-01-01: 92_601
-      2024-01-01: 95_101
-      2025-01-01: 97_801
+      2024-01-01: 95_201
+      2025-01-01: 97_501
       2026-01-01: 97_501
     amount:
       2021-01-01: 247.5
       2022-01-01: 347.20
       2023-01-01: 303.7
       2024-01-01: 117.40
-      2025-01-01: 89
+      2025-01-01: 119.30
       2026-01-01: 89.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_001
       2023-01-01: 92_701
-      2024-01-01: 95_201
-      2025-01-01: 97_901
+      2024-01-01: 95_301
+      2025-01-01: 97_601
       2026-01-01: 97_601
     amount:
       2021-01-01: 247.5
       2022-01-01: 337.20
       2023-01-01: 293.7
       2024-01-01: 107.40
-      2025-01-01: 89
+      2025-01-01: 109.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_101
       2023-01-01: 92_801
-      2024-01-01: 95_301
-      2025-01-01: .inf
+      2024-01-01: 95_401
+      2025-01-01: 97_701
       2026-01-01: .inf
     amount:
       2021-01-01: 247.5
       2022-01-01: 327.20
       2023-01-01: 283.7
       2024-01-01: 97.40
-      2025-01-01: 89
+      2025-01-01: 99.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_201
       2023-01-01: 92_901
-      2024-01-01: 95_401
-      2025-01-01: .inf
+      2024-01-01: 95_501
+      2025-01-01: 97_801
       2026-01-01: .inf
     amount:
       2021-01-01: 247.5
       2022-01-01: 317.20
       2023-01-01: 273.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_301
       2023-01-01: 93_001
-      2024-01-01: 95_501
+      2024-01-01: .inf
       2025-01-01: .inf
       2026-01-01: .inf
     amount:
@@ -544,7 +546,7 @@ brackets:
       2022-01-01: 307.20
       2023-01-01: 263.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -557,7 +559,7 @@ brackets:
       2022-01-01: 297.20
       2023-01-01: 253.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -570,7 +572,7 @@ brackets:
       2022-01-01: 287.20
       2023-01-01: 243.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -583,7 +585,7 @@ brackets:
       2022-01-01: 277.20
       2023-01-01: 233.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -596,7 +598,7 @@ brackets:
       2022-01-01: 267.20
       2023-01-01: 223.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -609,7 +611,7 @@ brackets:
       2022-01-01: 257.20
       2023-01-01: 213.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -622,7 +624,7 @@ brackets:
       2022-01-01: 247.20
       2023-01-01: 203.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -635,7 +637,7 @@ brackets:
       2022-01-01: 237.20
       2023-01-01: 193.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -648,7 +650,7 @@ brackets:
       2022-01-01: 227.20
       2023-01-01: 183.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -661,7 +663,7 @@ brackets:
       2022-01-01: 217.20
       2023-01-01: 173.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -674,7 +676,7 @@ brackets:
       2022-01-01: 207.20
       2023-01-01: 163.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -687,7 +689,7 @@ brackets:
       2022-01-01: 197.20
       2023-01-01: 153.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -700,7 +702,7 @@ brackets:
       2022-01-01: 187.20
       2023-01-01: 153.7
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -713,7 +715,7 @@ brackets:
       2022-01-01: 177.20
       2023-01-01: 153.70
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
@@ -726,7 +728,7 @@ brackets:
       2022-01-01: 167.20
       2023-01-01: 153.70
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
   - threshold:
       2022-01-01: .inf
@@ -737,5 +739,5 @@ brackets:
       2022-01-01: 167.20
       2023-01-01: 153.70
       2024-01-01: 87.40
-      2025-01-01: 89
+      2025-01-01: 89.30
       2026-01-01: 79.90
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_indiv.yaml b/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_indiv.yaml
index f510ab505ad..4e28a6e37c1 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_indiv.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_indiv.yaml
@@ -90,43 +90,43 @@
 
 - name: Case 10, 2025 taxable income in 2% bracket.
   period: 2025
-  absolute_error_margin: 1
+  absolute_error_margin: 0.01
   input:
     ar_taxable_income_indiv: 10_000
     state_code: AR
   output:
-    # 10_000 * 0.02 - 112 = 88
-    ar_income_tax_before_non_refundable_credits_indiv: 88
+    # DFA 2025 bracket: 10_000 * 0.02 - 111.98 = 88.02
+    ar_income_tax_before_non_refundable_credits_indiv: 88.02
 
 - name: Case 11, 2025 taxable income in 3.4% bracket.
   period: 2025
-  absolute_error_margin: 1
+  absolute_error_margin: 0.01
   input:
     ar_taxable_income_indiv: 20_000
     state_code: AR
   output:
-    # 20_000 * 0.034 - 288 = 392
-    ar_income_tax_before_non_refundable_credits_indiv: 392
+    # DFA 2025 bracket: 20_000 * 0.034 - 287.97 = 392.03
+    ar_income_tax_before_non_refundable_credits_indiv: 392.03
 
 - name: Case 12, 2025 taxable income in 3.9% bracket.
   period: 2025
-  absolute_error_margin: 1
+  absolute_error_margin: 0.01
   input:
     ar_taxable_income_indiv: 50_000
     state_code: AR
   output:
-    # 50_000 * 0.039 - 420 = 1_530
-    ar_income_tax_before_non_refundable_credits_indiv: 1_530
+    # DFA 2025 bracket: 50_000 * 0.039 - 419.96 = 1_530.04
+    ar_income_tax_before_non_refundable_credits_indiv: 1_530.04
 
 - name: Case 13, 2025 taxable income at $100,000.
   period: 2025
-  absolute_error_margin: 1
+  absolute_error_margin: 0.01
   input:
     ar_taxable_income_indiv: 100_000
     state_code: AR
   output:
-    # 100_000 * 0.039 - 89 = 3_811
-    ar_income_tax_before_non_refundable_credits_indiv: 3_811
+    # DFA 2025 bracket "$97,801 and over": 100_000 * 0.039 - 89.30 = 3_810.70
+    ar_income_tax_before_non_refundable_credits_indiv: 3_810.70
 
 # 2026 tests follow A.C.A. § 26-51-201(a)(4) as amended by HB1001 (2026 1st Extraordinary Session).
 # Bill schedules: (a)(4)(A) for net income <= $94,700, (a)(4)(B) for > $94,700, plus
@@ -299,3 +299,198 @@
     # 0.047 x 91,750 - 393.70 = 3,918.55 (previously the two duplicated
     # thresholds summed to a 787.40 reduction -> 3,524.85)
     ar_income_tax_before_non_refundable_credits_indiv: 3_918.55
+
+# 2025 and 2024 bracket adjustments, keyed to the DFA Indexed Tax Brackets cards
+# (2025_TaxBrackets.pdf and 2024_TaxBrackets.pdf, p1-2). Tax = 3.9% x net taxable
+# income - the row's minus adjustment.
+- name: AR 2025 bracket adjustment - top of the $26,400-$94,700 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_700
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$26,400 $94,700 3.90% $419.96":
+    # 0.039 x 94,700 - 419.96 = 3,273.34
+    ar_income_tax_before_non_refundable_credits_indiv: 3_273.34
+
+- name: AR 2025 bracket adjustment - first $94,701-$94,800 row PE previously skipped
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_701
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,701 $94,800 3.90% $399.30":
+    # 0.039 x 94,701 - 399.30 = 3,294.04
+    # (PE previously applied the $419.96-row amount, 420, here -> 3,273.34)
+    ar_income_tax_before_non_refundable_credits_indiv: 3_294.04
+
+- name: AR 2025 bracket adjustment - midpoint of the $94,701-$94,800 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_751
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,701 $94,800 3.90% $399.30":
+    # 0.039 x 94,751 - 399.30 = 3,295.99
+    # (2025 Regular Income Tax Table, $94,701-$94,801: $3,296)
+    ar_income_tax_before_non_refundable_credits_indiv: 3_295.99
+
+- name: AR 2025 bracket adjustment - top of the $94,701-$94,800 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_800
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,701 $94,800 3.90% $399.30":
+    # 0.039 x 94,800 - 399.30 = 3,297.90
+    ar_income_tax_before_non_refundable_credits_indiv: 3_297.90
+
+- name: AR 2025 bracket adjustment - first income in the $94,801-$94,900 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_801
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,801 $94,900 3.90% $389.30":
+    # 0.039 x 94,801 - 389.30 = 3,307.94
+    ar_income_tax_before_non_refundable_credits_indiv: 3_307.94
+
+- name: AR 2025 bracket adjustment - midpoint of the $94,801-$94,900 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_851
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,801 $94,900 3.90% $389.30":
+    # 0.039 x 94,851 - 389.30 = 3,309.89
+    # (2025 Regular Income Tax Table, $94,801-$94,901: $3,310)
+    ar_income_tax_before_non_refundable_credits_indiv: 3_309.89
+
+- name: AR 2025 bracket adjustment - first income in the $94,901-$95,000 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_901
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,901 $95,000 3.90% $379.30":
+    # 0.039 x 94,901 - 379.30 = 3,321.84
+    ar_income_tax_before_non_refundable_credits_indiv: 3_321.84
+
+- name: AR 2025 bracket adjustment - midpoint of the $94,901-$95,000 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_951
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,901 $95,000 3.90% $379.30":
+    # 0.039 x 94,951 - 379.30 = 3,323.79
+    # (2025 Regular Income Tax Table, $94,901-$95,001: $3,324)
+    ar_income_tax_before_non_refundable_credits_indiv: 3_323.79
+
+- name: AR 2025 bracket adjustment - top of the $94,901-$95,000 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 95_000
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$94,901 $95,000 3.90% $379.30":
+    # 0.039 x 95,000 - 379.30 = 3,325.70
+    ar_income_tax_before_non_refundable_credits_indiv: 3_325.70
+
+- name: AR 2025 bracket adjustment - first income in the $95,001-$95,100 row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 95_001
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$95,001 $95,100 3.90% $369.30":
+    # 0.039 x 95,001 - 369.30 = 3,335.74
+    ar_income_tax_before_non_refundable_credits_indiv: 3_335.74
+
+- name: AR 2025 bracket adjustment - top of the last $10-step row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 97_800
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$97,701 $97,800 3.90% $99.30":
+    # 0.039 x 97,800 - 99.30 = 3,714.90
+    ar_income_tax_before_non_refundable_credits_indiv: 3_714.90
+
+- name: AR 2025 bracket adjustment - first income in the and-over row
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 97_801
+    state_code: AR
+  output:
+    # DFA 2025 Indexed Tax Brackets row "$97,801 and over 3.90% $89.30":
+    # 0.039 x 97,801 - 89.30 = 3,724.94
+    ar_income_tax_before_non_refundable_credits_indiv: 3_724.94
+
+- name: AR 2024 bracket adjustment - inside the asterisked $94,301-$94,500 row
+  period: 2024
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_450
+    state_code: AR
+  output:
+    # DFA 2024 Indexed Tax Brackets row "*$94,301 *$94,500 3.90% $197.40" (asterisked, $200 wide):
+    # 0.039 x 94,450 - 197.40 = 3,486.15
+    # (2024 Regular Income Tax Table, $94,401-$94,501: $3,486; PE previously applied $187.40 here -> 3,496.15)
+    ar_income_tax_before_non_refundable_credits_indiv: 3_486.15
+
+- name: AR 2024 bracket adjustment - top of the asterisked $94,301-$94,500 row
+  period: 2024
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_500
+    state_code: AR
+  output:
+    # DFA 2024 Indexed Tax Brackets row "*$94,301 *$94,500 3.90% $197.40":
+    # 0.039 x 94,500 - 197.40 = 3,488.10
+    ar_income_tax_before_non_refundable_credits_indiv: 3_488.10
+
+- name: AR 2024 bracket adjustment - first income after the asterisked row
+  period: 2024
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_501
+    state_code: AR
+  output:
+    # DFA 2024 Indexed Tax Brackets row "$94,501 $94,600 3.90% $187.40":
+    # 0.039 x 94,501 - 187.40 = 3,498.14
+    ar_income_tax_before_non_refundable_credits_indiv: 3_498.14
+
+- name: AR 2024 bracket adjustment - top of the last $10-step row
+  period: 2024
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 95_500
+    state_code: AR
+  output:
+    # DFA 2024 Indexed Tax Brackets row "$95,401 $95,500 3.90% $97.40":
+    # 0.039 x 95,500 - 97.40 = 3,627.10
+    ar_income_tax_before_non_refundable_credits_indiv: 3_627.10
+
+- name: AR 2024 bracket adjustment - first income in the and-over row
+  period: 2024
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 95_501
+    state_code: AR
+  output:
+    # DFA 2024 Indexed Tax Brackets row "$95,501 and over 3.90% $87.40":
+    # 0.039 x 95,501 - 87.40 = 3,637.14
+    ar_income_tax_before_non_refundable_credits_indiv: 3_637.14
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_joint.yaml b/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_joint.yaml
index 5dc32d59210..96d1a5f83b0 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_joint.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/ar_income_tax_before_non_refundable_credits_joint.yaml
@@ -104,9 +104,9 @@
     ar_low_income_tax_joint: 300
     state_code: AR
   output:
-    # Regular: 20_000 * 0.034 - 288 = 392
+    # Regular: 20_000 * 0.034 - 287.97 = 392.03
     # Low income cap: 300
-    # min(392, 300) = 300
+    # min(392.03, 300) = 300
     ar_income_tax_before_non_refundable_credits_joint: 300
 
 - name: Case 11, 2025 joint taxable income in 3.9% bracket, no low income cap.
@@ -117,10 +117,10 @@
     ar_low_income_tax_joint: 5_000
     state_code: AR
   output:
-    # Regular: 50_000 * 0.039 - 420 = 1_530
+    # Regular: 50_000 * 0.039 - 419.96 = 1_530.04
     # Low income cap: 5_000
-    # min(1_530, 5_000) = 1_530
-    ar_income_tax_before_non_refundable_credits_joint: 1_530
+    # min(1_530.04, 5_000) = 1_530.04
+    ar_income_tax_before_non_refundable_credits_joint: 1_530.04
 
 - name: AR 2021 MFJ with two dependents just above the low-income table cutoff uses the regular table (pe-us 9024)
   period: 2021

From de24b32e01d3f21813565404d70b19939c0d7c33 Mon Sep 17 00:00:00 2001
From: Max Ghenis <max@policyengine.org>
Date: Fri, 25 Sep 2026 12:53:39 -0400
Subject: [PATCH 2/3] Add AR schedule differential and invariant tests for
 2021-2026

Compares rate.calc(ti) * ti - reduction.calc(ti) at every integer
taxable income 0-150,000 against an independent transcription of each
DFA Indexed Tax Brackets card (2021-2025) and Act 1 of 2026, and checks
that tax is non-negative, never falls except the statutory $2.66 drop
Act 1 of 2026 writes at $94,700 -> $94,701, and that reduction
thresholds strictly increase. On upstream/main the 2024 and 2025
differential cases fail.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../tests/test_ar_income_tax_schedule.py      | 173 ++++++++++++++++++
 1 file changed, 173 insertions(+)
 create mode 100644 policyengine_us/tests/test_ar_income_tax_schedule.py

diff --git a/policyengine_us/tests/test_ar_income_tax_schedule.py b/policyengine_us/tests/test_ar_income_tax_schedule.py
new file mode 100644
index 00000000000..b0a36ffbcf1
--- /dev/null
+++ b/policyengine_us/tests/test_ar_income_tax_schedule.py
@@ -0,0 +1,173 @@
+"""Arkansas regular income tax schedule: differential and invariant tests.
+
+`ar_income_tax_before_non_refundable_credits_indiv` computes
+`rate.calc(ti) * ti - reduction.calc(ti)` from two single_amount scales whose
+rows are shared across years, so a mis-keyed row in one year's column (a
+skipped DFA row, an ignored asterisked two-row range, a duplicated
+threshold) silently shifts every later bracket. These tests compare every
+integer taxable income against an independent transcription of each year's
+source:
+
+- 2021-2025: DFA Indexed Tax Brackets cards, e.g.
+  https://www.dfa.arkansas.gov/wp-content/uploads/2025_TaxBrackets.pdf#page=1
+  Rows from the top of the flat rate bracket upward form a $100 ladder whose
+  minus adjustment falls $10 per row. Asterisked rows span $200, so the next
+  row's start is skipped.
+- 2026: Act 1 of 2026 (1st Extraordinary Session), A.C.A. 26-51-201(a)(4).
+
+Invariants (every integer taxable income, 2021-2026): tax is non-negative;
+reduction thresholds are strictly increasing; tax never falls as taxable
+income rises, except the one drop Act 1 of 2026 writes into the statute:
+(a)(4)(A) taxes $94,700 at $3,136.70, while (a)(4)(B) less the $290
+(a)(4)(C) adjustment taxes $94,701 at $3,134.04.
+"""
+
+import numpy as np
+import pytest
+
+from policyengine_us.system import system
+
+P = system.parameters.gov.states.ar.tax.income.rates.main
+YEARS = range(2021, 2027)
+TAXABLE_INCOME = np.concatenate(
+    [np.arange(0, 150_001, dtype=float), [250_000.0, 1_000_000.0]]
+)
+
+
+def ladder(first_threshold, last_threshold, first_adjustment, wide_rows=()):
+    """$100 rows from first to last threshold, $10 less adjustment per row.
+
+    `wide_rows` are the starts of asterisked rows that span $200.
+    """
+    skipped = {start + 100 for start in wide_rows}
+    starts = [
+        t for t in range(first_threshold, last_threshold + 1, 100) if t not in skipped
+    ]
+    return [(t, first_adjustment - 10 * k) for k, t in enumerate(starts)]
+
+
+# (From, rate, minus adjustment) as printed on each DFA card.
+DFA_CARDS = {
+    2021: [
+        (0, 0, 0),
+        (4_800, 0.02, 95.98),
+        (9_500, 0.03, 190.97),
+        (14_300, 0.034, 248.17),
+        (23_600, 0.05, 439.96),
+        (39_700, 0.059, 797.25),
+        (84_501, 0.059, 687.50),
+        (85_501, 0.059, 587.50),
+        (86_501, 0.059, 487.50),
+        (87_901, 0.059, 387.50),
+        (89_001, 0.059, 287.50),
+        (90_101, 0.059, 247.50),
+    ],
+    2022: [
+        (0, 0, 0),
+        (5_100, 0.02, 101.98),
+        (10_300, 0.03, 204.97),
+        (14_700, 0.034, 263.77),
+        (24_300, 0.049, 628.25),
+    ]
+    + [
+        (t, 0.049, a)
+        for t, a in ladder(87_001, 91_801, 627.20, wide_rows=(87_401, 90_901))
+    ],
+    2023: [
+        (0, 0, 0),
+        (5_300, 0.02, 105.98),
+        (10_600, 0.03, 211.97),
+        (15_100, 0.034, 272.37),
+        (25_000, 0.047, 597.35),
+    ]
+    + [
+        (t, 0.047, a)
+        for t, a in ladder(89_601, 94_201, 583.70, wide_rows=(90_001, 90_901, 93_601))
+    ],
+    2024: [
+        (0, 0, 0),
+        (5_500, 0.02, 109.98),
+        (10_900, 0.03, 218.97),
+        (15_600, 0.034, 281.37),
+        (25_700, 0.039, 409.86),
+    ]
+    + [(t, 0.039, a) for t, a in ladder(92_301, 95_501, 397.40, wide_rows=(94_301,))],
+    2025: [
+        (0, 0, 0),
+        (5_600, 0.02, 111.98),
+        (11_200, 0.03, 223.97),
+        (16_000, 0.034, 287.97),
+        (26_400, 0.039, 419.96),
+    ]
+    + [(t, 0.039, a) for t, a in ladder(94_701, 97_801, 399.30)],
+}
+
+
+def card_tax(year, ti):
+    rows = DFA_CARDS[year]
+    starts = np.array([r[0] for r in rows])
+    i = np.searchsorted(starts, ti, side="right") - 1
+    rate = np.array([r[1] for r in rows])[i]
+    adjustment = np.array([r[2] for r in rows])[i]
+    return rate * ti - adjustment
+
+
+def act_1_of_2026_tax(ti):
+    # (a)(4)(A), net income <= $94,700: marginal rates from each row's "From".
+    low = sum(
+        rate * np.clip(ti - start, 0, end - start)
+        for start, end, rate in [
+            (5_600, 11_200, 0.02),
+            (11_200, 16_000, 0.03),
+            (16_000, 26_400, 0.034),
+            (26_400, np.inf, 0.037),
+        ]
+    )
+    # (a)(4)(B), net income > $94,700: 2% on the first $4,700, 3.7% above.
+    high = 0.02 * 4_700 + 0.037 * (ti - 4_700)
+    # (a)(4)(C): $290 at $94,701-$94,800, $10 less per $100, $0 from $97,601.
+    step = np.floor((np.ceil(ti) - 94_701) / 100)
+    high -= np.where(ti <= 97_600, 290 - 10 * step, 0)
+    return np.where(ti <= 94_700, low, high)
+
+
+def model_tax(year, ti):
+    instant = f"{year}-01-01"
+    return P.rate(instant).calc(ti) * ti - P.reduction(instant).calc(ti)
+
+
+def source_tax(year, ti):
+    return act_1_of_2026_tax(ti) if year == 2026 else card_tax(year, ti)
+
+
+@pytest.mark.parametrize("year", YEARS)
+def test_ar_schedule_matches_source_at_every_integer_income(year):
+    diff = model_tax(year, TAXABLE_INCOME) - source_tax(year, TAXABLE_INCOME)
+    bad = np.flatnonzero(np.abs(diff) > 0.005)
+    assert bad.size == 0, (
+        f"{year}: {bad.size} incomes differ from the source, first at "
+        f"{TAXABLE_INCOME[bad[0]]:,.0f} (model - source = {diff[bad[0]]:+.2f})"
+    )
+
+
+# {income: change in tax from income to income + 1} where the statute itself
+# makes tax fall: A.C.A. 26-51-201(a)(4)(A) vs (a)(4)(B)-(C), Act 1 of 2026.
+STATUTORY_DROPS = {2026: {94_700: -2.66}}
+
+
+@pytest.mark.parametrize("year", YEARS)
+def test_ar_schedule_tax_is_nonnegative_and_nondecreasing(year):
+    tax = model_tax(year, TAXABLE_INCOME)
+    assert tax.min() >= -1e-9
+    change = np.diff(tax)
+    falls = {
+        int(TAXABLE_INCOME[i]): round(float(change[i]), 2)
+        for i in np.flatnonzero(change < -1e-9)
+    }
+    assert falls == STATUTORY_DROPS.get(year, {})
+
+
+@pytest.mark.parametrize("year", YEARS)
+def test_ar_reduction_thresholds_strictly_increase(year):
+    thresholds = [t for t in P.reduction(f"{year}-01-01").thresholds if t < np.inf]
+    assert all(a < b for a, b in zip(thresholds, thresholds[1:])), thresholds

From 304550618b6179f8b06f8572cd30305c57fe6c7c Mon Sep 17 00:00:00 2001
From: Max Ghenis <max@policyengine.org>
Date: Fri, 25 Sep 2026 13:05:13 -0400
Subject: [PATCH 3/3] Check reduction.yaml row thresholds directly, not the
 merged loaded scale

The loaded scale can't show a duplicated or out-of-order row: add_bracket
sorts thresholds and sums duplicate amounts. Reading each bracket's own
threshold flags the pre-#9026 2023 duplicates (91,701 and 91,801), which
the previous check passed. Caught in independent review.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../tests/test_ar_income_tax_schedule.py      | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/policyengine_us/tests/test_ar_income_tax_schedule.py b/policyengine_us/tests/test_ar_income_tax_schedule.py
index b0a36ffbcf1..3e77abb8779 100644
--- a/policyengine_us/tests/test_ar_income_tax_schedule.py
+++ b/policyengine_us/tests/test_ar_income_tax_schedule.py
@@ -15,9 +15,10 @@
   row's start is skipped.
 - 2026: Act 1 of 2026 (1st Extraordinary Session), A.C.A. 26-51-201(a)(4).
 
-Invariants (every integer taxable income, 2021-2026): tax is non-negative;
-reduction thresholds are strictly increasing; tax never falls as taxable
-income rises, except the one drop Act 1 of 2026 writes into the statute:
+Invariants (2021-2026): reduction.yaml rows carry strictly increasing
+finite thresholds, with every .inf row after them. At every integer taxable
+income, tax is non-negative and never falls as income rises, except the one
+drop Act 1 of 2026 writes into the statute:
 (a)(4)(A) taxes $94,700 at $3,136.70, while (a)(4)(B) less the $290
 (a)(4)(C) adjustment taxes $94,701 at $3,134.04.
 """
@@ -168,6 +169,12 @@ def test_ar_schedule_tax_is_nonnegative_and_nondecreasing(year):
 
 
 @pytest.mark.parametrize("year", YEARS)
-def test_ar_reduction_thresholds_strictly_increase(year):
-    thresholds = [t for t in P.reduction(f"{year}-01-01").thresholds if t < np.inf]
-    assert all(a < b for a, b in zip(thresholds, thresholds[1:])), thresholds
+def test_ar_reduction_rows_have_strictly_increasing_thresholds(year):
+    # Read each YAML row's own threshold: the loaded scale can't show a
+    # mis-keyed row, because add_bracket sorts thresholds and sums the amounts
+    # of duplicates.
+    instant = f"{year}-01-01"
+    thresholds = [bracket.threshold(instant) for bracket in P.reduction.brackets]
+    finite = [t for t in thresholds if t < np.inf]
+    assert thresholds[: len(finite)] == finite, thresholds
+    assert all(a < b for a, b in zip(finite, finite[1:])), finite