diff --git a/changelog.d/ar-hb1001-2026-rates.changed.md b/changelog.d/ar-hb1001-2026-rates.changed.md
new file mode 100644
index 00000000000..e2624596d02
--- /dev/null
+++ b/changelog.d/ar-hb1001-2026-rates.changed.md
@@ -0,0 +1 @@
+Apply Arkansas HB1001 (2026 1st Extraordinary Session) individual income tax rate cuts effective tax year 2026.
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 b7d37fc3a5d..9cd808fa17c 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
@@ -26,6 +26,10 @@ metadata:
     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: 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)
+    href: https://arkleg.state.ar.us/Bills/Detail?id=hb1001&ddBienniumSession=2025%2F2026S1
 
 brackets:
   - threshold:
@@ -49,6 +53,7 @@ brackets:
         2023-01-01: 5_300
         2024-01-01: 5_500
         2025-01-01: 5_600
+        2026-01-01: 5_600
       metadata:
         uprating: gov.irs.uprating
         rounding:
@@ -68,6 +73,7 @@ brackets:
         2023-01-01: 10_600
         2024-01-01: 10_900
         2025-01-01: 11_200
+        2026-01-01: 11_200
       metadata:
         uprating: gov.irs.uprating
         rounding:
@@ -88,6 +94,7 @@ brackets:
         2023-01-01: 15_100
         2024-01-01: 15_600
         2025-01-01: 16_000
+        2026-01-01: 16_000
       metadata:
         uprating: gov.irs.uprating
         rounding:
@@ -108,6 +115,7 @@ brackets:
         2023-01-01: 25_000
         2024-01-01: 25_700
         2025-01-01: 26_400
+        2026-01-01: 26_400
       metadata:
         uprating: gov.irs.uprating
         rounding:
@@ -119,6 +127,7 @@ brackets:
       2022-01-01: 0.049
       2023-01-01: 0.047
       2024-01-01: 0.039
+      2026-01-01: 0.037
   - threshold:
       values:
         2014-01-01: 35_100
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 c5cb4e61dfd..6276e34b3d0 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
@@ -17,6 +17,10 @@ metadata:
     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: 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)
+    href: https://arkleg.state.ar.us/Bills/Detail?id=hb1001&ddBienniumSession=2025%2F2026S1
 brackets:
   - threshold:
       2021-01-01: 0
@@ -30,444 +34,518 @@ brackets:
       2023-01-01: 5_300
       2024-01-01: 5_500
       2025-01-01: 5_600
+      2026-01-01: 5_600
     amount:
       2021-01-01: 95.98
       2022-01-01: 101.98
       2023-01-01: 105.98
       2024-01-01: 109.98
       2025-01-01: 112
+      2026-01-01: 112
   - threshold:
       2021-01-01: 9_500
       2022-01-01: 10_300
       2023-01-01: 10_600
       2024-01-01: 10_900
       2025-01-01: 11_200
+      2026-01-01: 11_200
     amount:
       2021-01-01: 190.97
       2022-01-01: 204.97
       2023-01-01: 211.97
       2024-01-01: 218.97
       2025-01-01: 224
+      2026-01-01: 224
   - threshold:
       2021-01-01: 14_300
       2022-01-01: 14_700
       2023-01-01: 15_100
       2024-01-01: 15_600
       2025-01-01: 16_000
+      2026-01-01: 16_000
     amount:
       2021-01-01: 248.17
       2022-01-01: 263.77
       2023-01-01: 272.37
       2024-01-01: 281.37
       2025-01-01: 288
+      2026-01-01: 288
   - threshold:
       2021-01-01: 23_600
       2022-01-01: 24_300
       2023-01-01: 25_000
       2024-01-01: 25_700
       2025-01-01: 26_400
+      2026-01-01: 26_400
     amount:
       2021-01-01: 439.96
       2022-01-01: 628.25
       2023-01-01: 597.35
       2024-01-01: 409.86
       2025-01-01: 420
+      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
+      2026-01-01: 94_701
     amount:
       2021-01-01: 797.25
       2022-01-01: 627.20
       2023-01-01: 583.70
       2024-01-01: 397.40
       2025-01-01: 369
+      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
+      2026-01-01: 94_801
     amount:
       2021-01-01: 687.5
       2022-01-01: 617.20
       2023-01-01: 573.70
       2024-01-01: 387.40
       2025-01-01: 359
+      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
+      2026-01-01: 94_901
     amount:
       2021-01-01: 587.5
       2022-01-01: 607.20
       2023-01-01: 563.70
       2024-01-01: 377.40
       2025-01-01: 349
+      2026-01-01: 349.90
   - threshold:
       2021-01-01: 86_501
       2022-01-01: 87_301
       2023-01-01: 90_001
       2024-01-01: 92_601
       2025-01-01: 95_301
+      2026-01-01: 95_001
     amount:
       2021-01-01: 487.5
       2022-01-01: 597.20
       2023-01-01: 553.70
       2024-01-01: 367.40
       2025-01-01: 339
+      2026-01-01: 339.90
   - threshold:
       2021-01-01: 87_901
       2022-01-01: 87_401
       2023-01-01: 90_201
       2024-01-01: 92_701
       2025-01-01: 95_401
+      2026-01-01: 95_101
     amount:
       2021-01-01: 387.5
       2022-01-01: 587.20
       2023-01-01: 543.70
       2024-01-01: 357.40
       2025-01-01: 329
+      2026-01-01: 329.90
   - threshold:
       2021-01-01: 89_001
       2022-01-01: 87_601
       2023-01-01: 90_301
       2024-01-01: 92_801
       2025-01-01: 95_501
+      2026-01-01: 95_201
     amount:
       2021-01-01: 287.5
       2022-01-01: 577.20
       2023-01-01: 533.70
       2024-01-01: 347.40
       2025-01-01: 319
+      2026-01-01: 319.90
   - threshold:
       2021-01-01: 90_101
       2022-01-01: 87_701
       2023-01-01: 90_401
       2024-01-01: 92_901
       2025-01-01: 95_601
+      2026-01-01: 95_301
     amount:
       2021-01-01: 247.5
       2022-01-01: 567.20
       2023-01-01: 523.70
       2024-01-01: 337.40
       2025-01-01: 309
+      2026-01-01: 309.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 87_801
       2023-01-01: 90_501
       2024-01-01: 93_001
       2025-01-01: 95_701
+      2026-01-01: 95_401
     amount:
       2021-01-01: 247.5
       2022-01-01: 557.20
       2023-01-01: 513.70
       2024-01-01: 327.40
       2025-01-01: 299
+      2026-01-01: 299.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 87_901
       2023-01-01: 90_601
       2024-01-01: 93_101
       2025-01-01: 95_801
+      2026-01-01: 95_501
     amount:
       2021-01-01: 247.5
       2022-01-01: 547.20
       2023-01-01: 503.70
       2024-01-01: 317.40
       2025-01-01: 289
+      2026-01-01: 289.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_001
       2023-01-01: 90_701
       2024-01-01: 93_201
       2025-01-01: 95_901
+      2026-01-01: 95_601
     amount:
       2021-01-01: 247.5
       2022-01-01: 537.20
       2023-01-01: 493.70
       2024-01-01: 307.40
       2025-01-01: 279
+      2026-01-01: 279.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_101
       2023-01-01: 90_801
       2024-01-01: 93_301
       2025-01-01: 96_001
+      2026-01-01: 95_701
     amount:
       2021-01-01: 247.5
       2022-01-01: 527.20
       2023-01-01: 483.70
       2024-01-01: 297.40
       2025-01-01: 269
+      2026-01-01: 269.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_201
       2023-01-01: 90_901
       2024-01-01: 93_401
       2025-01-01: 96_101
+      2026-01-01: 95_801
     amount:
       2021-01-01: 247.5
       2022-01-01: 517.20
       2023-01-01: 473.70
       2024-01-01: 287.40
       2025-01-01: 259
+      2026-01-01: 259.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_301
       2023-01-01: 91_101
       2024-01-01: 93_501
       2025-01-01: 96_201
+      2026-01-01: 95_901
     amount:
       2021-01-01: 247.5
       2022-01-01: 507.20
       2023-01-01: 463.70
       2024-01-01: 277.40
       2025-01-01: 249
+      2026-01-01: 249.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_401
       2023-01-01: 91_201
       2024-01-01: 93_601
       2025-01-01: 96_301
+      2026-01-01: 96_001
     amount:
       2021-01-01: 247.5
       2022-01-01: 497.20
       2023-01-01: 453.70
       2024-01-01: 267.40
       2025-01-01: 239
+      2026-01-01: 239.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_501
       2023-01-01: 91_301
       2024-01-01: 93_701
       2025-01-01: 96_401
+      2026-01-01: 96_101
     amount:
       2021-01-01: 247.5
       2022-01-01: 487.20
       2023-01-01: 443.70
       2024-01-01: 257.40
       2025-01-01: 229
+      2026-01-01: 229.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_601
       2023-01-01: 91_401
       2024-01-01: 93_801
       2025-01-01: 96_501
+      2026-01-01: 96_201
     amount:
       2021-01-01: 247.5
       2022-01-01: 477.20
       2023-01-01: 433.70
       2024-01-01: 247.40
       2025-01-01: 219
+      2026-01-01: 219.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_701
       2023-01-01: 91_501
       2024-01-01: 93_901
       2025-01-01: 96_601
+      2026-01-01: 96_301
     amount:
       2021-01-01: 247.5
       2022-01-01: 467.20
       2023-01-01: 423.70
       2024-01-01: 237.40
       2025-01-01: 209
+      2026-01-01: 209.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_801
       2023-01-01: 91_601
       2024-01-01: 94_001
       2025-01-01: 96_701
+      2026-01-01: 96_401
     amount:
       2021-01-01: 247.5
       2022-01-01: 457.20
       2023-01-01: 413.70
       2024-01-01: 227.40
       2025-01-01: 199
+      2026-01-01: 199.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 88_901
       2023-01-01: 91_701
       2024-01-01: 94_101
       2025-01-01: 96_801
+      2026-01-01: 96_501
     amount:
       2021-01-01: 247.5
       2022-01-01: 447.20
       2023-01-01: 403.70
       2024-01-01: 217.40
       2025-01-01: 189
+      2026-01-01: 189.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_001
       2023-01-01: 91_801
       2024-01-01: 94_201
       2025-01-01: 96_901
+      2026-01-01: 96_601
     amount:
       2021-01-01: 247.5
       2022-01-01: 437.20
       2023-01-01: 393.70
       2024-01-01: 207.40
       2025-01-01: 179
+      2026-01-01: 179.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_101
       2023-01-01: 91_701
       2024-01-01: 94_301
       2025-01-01: 97_001
+      2026-01-01: 96_701
     amount:
       2021-01-01: 247.5
       2022-01-01: 427.20
       2023-01-01: 383.70
       2024-01-01: 197.40
       2025-01-01: 169
+      2026-01-01: 169.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_201
       2023-01-01: 91_801
       2024-01-01: 94_401
       2025-01-01: 97_101
+      2026-01-01: 96_801
     amount:
       2021-01-01: 247.5
       2022-01-01: 417.20
       2023-01-01: 373.70
       2024-01-01: 187.40
       2025-01-01: 159
+      2026-01-01: 159.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_301
       2023-01-01: 91_901
       2024-01-01: 94_501
       2025-01-01: 97_201
+      2026-01-01: 96_901
     amount:
       2021-01-01: 247.5
       2022-01-01: 407.20
       2023-01-01: 363.70
       2024-01-01: 177.40
       2025-01-01: 149
+      2026-01-01: 149.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_401
       2023-01-01: 92_001
       2024-01-01: 94_601
       2025-01-01: 97_301
+      2026-01-01: 97_001
     amount:
       2021-01-01: 247.5
       2022-01-01: 397.20
       2023-01-01: 353.70
       2024-01-01: 167.40
       2025-01-01: 139
+      2026-01-01: 139.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_501
       2023-01-01: 92_101
       2024-01-01: 94_701
       2025-01-01: 97_401
+      2026-01-01: 97_101
     amount:
       2021-01-01: 247.5
       2022-01-01: 387.20
       2023-01-01: 343.70
       2024-01-01: 157.40
       2025-01-01: 129
+      2026-01-01: 129.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_601
       2023-01-01: 92_201
       2024-01-01: 94_801
       2025-01-01: 97_501
+      2026-01-01: 97_201
     amount:
       2021-01-01: 247.5
       2022-01-01: 377.20
       2023-01-01: 333.70
       2024-01-01: 147.40
       2025-01-01: 119
+      2026-01-01: 119.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_701
       2023-01-01: 92_301
       2024-01-01: 94_901
       2025-01-01: 97_601
+      2026-01-01: 97_301
     amount:
       2021-01-01: 247.5
       2022-01-01: 367.20
       2023-01-01: 323.70
       2024-01-01: 137.40
       2025-01-01: 109
+      2026-01-01: 109.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_801
       2023-01-01: 92_401
       2024-01-01: 95_001
       2025-01-01: 97_701
+      2026-01-01: 97_401
     amount:
       2021-01-01: 247.5
       2022-01-01: 357.20
       2023-01-01: 313.70
       2024-01-01: 127.40
       2025-01-01: 99
+      2026-01-01: 99.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 89_901
       2023-01-01: 92_501
       2024-01-01: 95_101
       2025-01-01: 97_801
+      2026-01-01: 97_501
     amount:
       2021-01-01: 247.5
       2022-01-01: 347.20
       2023-01-01: 303.70
       2024-01-01: 117.40
       2025-01-01: 89
+      2026-01-01: 89.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_001
       2023-01-01: 92_601
       2024-01-01: 95_201
       2025-01-01: 97_901
+      2026-01-01: 97_601
     amount:
       2021-01-01: 247.5
       2022-01-01: 337.20
       2023-01-01: 293.70
       2024-01-01: 107.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_101
       2023-01-01: 92_701
       2024-01-01: 95_301
       2025-01-01: .inf
+      2026-01-01: .inf
     amount:
       2021-01-01: 247.5
       2022-01-01: 327.20
       2023-01-01: 283.70
       2024-01-01: 97.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_201
       2023-01-01: 92_801
       2024-01-01: 95_401
       2025-01-01: .inf
+      2026-01-01: .inf
     amount:
       2021-01-01: 247.5
       2022-01-01: 317.20
       2023-01-01: 273.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_301
       2023-01-01: 92_901
       2024-01-01: 95_501
       2025-01-01: .inf
+      2026-01-01: .inf
     amount:
       2021-01-01: 247.5
       2022-01-01: 307.20
       2023-01-01: 263.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_401
@@ -480,6 +558,7 @@ brackets:
       2023-01-01: 253.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_501
@@ -492,6 +571,7 @@ brackets:
       2023-01-01: 243.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_601
@@ -504,6 +584,7 @@ brackets:
       2023-01-01: 233.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_701
@@ -516,6 +597,7 @@ brackets:
       2023-01-01: 223.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_801
@@ -528,6 +610,7 @@ brackets:
       2023-01-01: 213.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 90_901
@@ -540,6 +623,7 @@ brackets:
       2023-01-01: 203.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_101
@@ -552,6 +636,7 @@ brackets:
       2023-01-01: 193.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_201
@@ -564,6 +649,7 @@ brackets:
       2023-01-01: 183.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_301
@@ -576,6 +662,7 @@ brackets:
       2023-01-01: 173.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_401
@@ -588,6 +675,7 @@ brackets:
       2023-01-01: 163.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_501
@@ -600,6 +688,7 @@ brackets:
       2023-01-01: 153.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_601
@@ -612,6 +701,7 @@ brackets:
       2023-01-01: 153.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_701
@@ -624,6 +714,7 @@ brackets:
       2023-01-01: 153.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2021-01-01: .inf
       2022-01-01: 91_801
@@ -636,6 +727,7 @@ brackets:
       2023-01-01: 153.70
       2024-01-01: 87.40
       2025-01-01: 89
+      2026-01-01: 79.90
   - threshold:
       2022-01-01: .inf
       2023-01-01: .inf
@@ -646,3 +738,4 @@ brackets:
       2023-01-01: 153.70
       2024-01-01: 87.40
       2025-01-01: 89
+      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 f623d52f36b..d809157414e 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
@@ -48,7 +48,7 @@
     # 562.366 + round((25_000-24_301) * 0.049) = 596
     ar_income_tax_before_non_refundable_credits_indiv: 596
 
-- name: AR income tax rates - taxable income from $15,100 to $25,000 
+- name: AR income tax rates - taxable income from $15,100 to $25,000
   period: 2023
   absolute_error_margin: 1
   input:
@@ -58,7 +58,7 @@
     # 20_000 * 0.034 - 272.37 = 407.63
     ar_income_tax_before_non_refundable_credits_indiv: 407.63
 
-- name: AR income tax rates - taxable income from $25,000 to $89,600 
+- name: AR income tax rates - taxable income from $25,000 to $89,600
   period: 2023
   absolute_error_margin: 1
   input:
@@ -127,3 +127,141 @@
   output:
     # 100_000 * 0.039 - 89 = 3_811
     ar_income_tax_before_non_refundable_credits_indiv: 3_811
+
+# 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
+# the (a)(4)(C) bracket adjustment for $94,701 - $97,600.
+- name: AR HB1001 2026 - 0% bracket, no tax
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 5_000
+    state_code: AR
+  output:
+    # within $0 - $5,599 0% bracket
+    ar_income_tax_before_non_refundable_credits_indiv: 0
+
+- name: AR HB1001 2026 - 2% bracket
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 10_000
+    state_code: AR
+  output:
+    # ($10,000 - $5,600) * 0.02 = $88
+    ar_income_tax_before_non_refundable_credits_indiv: 88
+
+- name: AR HB1001 2026 - 3% bracket
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 15_000
+    state_code: AR
+  output:
+    # $112 + ($15,000 - $11,200) * 0.03 = $112 + $114 = $226
+    ar_income_tax_before_non_refundable_credits_indiv: 226
+
+- name: AR HB1001 2026 - 3.4% bracket
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 20_000
+    state_code: AR
+  output:
+    # $112 + $144 + ($20,000 - $16,000) * 0.034 = $256 + $136 = $392
+    ar_income_tax_before_non_refundable_credits_indiv: 392
+
+- name: AR HB1001 2026 - top low-income bracket (3.7%)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 50_000
+    state_code: AR
+  output:
+    # $609.60 + ($50,000 - $26,400) * 0.037 = $609.60 + $873.20 = $1,482.80
+    ar_income_tax_before_non_refundable_credits_indiv: 1_482.80
+
+- name: AR HB1001 2026 - boundary at $94,700 under (a)(4)(A)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_700
+    state_code: AR
+  output:
+    # $609.60 + ($94,700 - $26,400) * 0.037 = $609.60 + $2,527.10 = $3,136.70
+    ar_income_tax_before_non_refundable_credits_indiv: 3_136.70
+
+- name: AR HB1001 2026 - bracket adjustment top ($94,701, $290 adj)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 94_701
+    state_code: AR
+  output:
+    # (a)(4)(B): $94 + ($94,701 - $4,700) * 0.037 = $3,424.04
+    # (a)(4)(C) adjustment: -$290 -> $3,134.04
+    ar_income_tax_before_non_refundable_credits_indiv: 3_134.04
+
+- name: AR HB1001 2026 - bracket adjustment mid ($95,500, $220 adj)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 95_500
+    state_code: AR
+  output:
+    # (a)(4)(B): $94 + ($95,500 - $4,700) * 0.037 = $3,453.60
+    # (a)(4)(C) row "$95,401-$95,500" adjustment: -$220 -> $3,233.60
+    ar_income_tax_before_non_refundable_credits_indiv: 3_233.60
+
+- name: AR HB1001 2026 - bracket adjustment mid ($96,500, $120 adj)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 96_500
+    state_code: AR
+  output:
+    # (a)(4)(B): $94 + ($96,500 - $4,700) * 0.037 = $3,490.60
+    # (a)(4)(C) row "$96,401-$96,500" adjustment: -$120 -> $3,370.60
+    ar_income_tax_before_non_refundable_credits_indiv: 3_370.60
+
+- name: AR HB1001 2026 - bracket adjustment mid ($97,000, $70 adj)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 97_000
+    state_code: AR
+  output:
+    # (a)(4)(B): $94 + ($97,000 - $4,700) * 0.037 = $3,509.10
+    # (a)(4)(C) row "$96,901-$97,000" adjustment: -$70 -> $3,439.10
+    ar_income_tax_before_non_refundable_credits_indiv: 3_439.10
+
+- name: AR HB1001 2026 - bracket adjustment bottom ($97,600, $10 adj)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 97_600
+    state_code: AR
+  output:
+    # (a)(4)(B): $94 + ($97,600 - $4,700) * 0.037 = $3,531.30
+    # (a)(4)(C) adjustment: -$10 -> $3,521.30
+    ar_income_tax_before_non_refundable_credits_indiv: 3_521.30
+
+- name: AR HB1001 2026 - just past adjustment ($97,601, $0 adj)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 97_601
+    state_code: AR
+  output:
+    # (a)(4)(B): $94 + ($97,601 - $4,700) * 0.037 = $3,531.34
+    ar_income_tax_before_non_refundable_credits_indiv: 3_531.34
+
+- name: AR HB1001 2026 - high income (a)(4)(B)
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    ar_taxable_income_indiv: 200_000
+    state_code: AR
+  output:
+    # $94 + ($200,000 - $4,700) * 0.037 = $7,320.10
+    ar_income_tax_before_non_refundable_credits_indiv: 7_320.10