Fix duplicate 2024 Arkansas low-income table threshold and guard scale thresholds

changelog.d/fix-ar-low-income-duplicate-threshold.fixed.md

@@ -0,0 +1 @@
+Corrected the 2024 Arkansas low-income tax table for head of household and surviving spouse filers with two or more dependents, whose $92 row shared the $24,200 threshold of the $104 row and was summed into a $196 row; removed a duplicated top bracket from the IRS SOI AGI-by-size calibration scale; and added tests that fail when any parameter scale repeats a threshold (other than +inf) or an Arkansas low-income table stops rising with AGI.

policyengine_us/parameters/calibration/gov/irs/soi/agi/total_agi.yaml

@@ -132,10 +132,3 @@ brackets:
         uprating: calibration.gov.cbo.income_by_source.adjusted_gross_income
       values:
         2015-01-01: 824_093_126_000
-  - threshold:
-      2015-01-01: 10_000_000
-    amount:
-      metadata:
-        uprating: calibration.gov.cbo.income_by_source.adjusted_gross_income
-      values:
-        2015-01-01: 824_093_126_000

policyengine_us/parameters/gov/states/ar/tax/income/rates/low_income_tax_tables/head_of_household/two_or_more_dependents.yaml

@@ -26,9 +26,9 @@ metadata:
     - title: Arkansas Income Tax Instructions, 2021, Low Income Tax Tables
       href: https://www.dfa.arkansas.gov/wp-content/uploads/2021_AR1000F_and_AR1000NR_Instructions.pdf#page=26
     - title: Arkansas Income Tax Instructions, 2023, Low Income Tax Tables
-      href: https://www.dfa.arkansas.gov/wp-content/uploads/2023_AR1000F_and_AR1000NR_Instructions.pdf#page=25
+      href: https://www.dfa.arkansas.gov/wp-content/uploads/2023_AR1000F_and_AR1000NR_Instructions.pdf#page=29
     - title: Arkansas Income Tax Instructions, 2024, Low Income Tax Tables
-      href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=24
+      href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=28
     - title: Arkansas Income Tax Instructions, 2025, Low Income Tax Tables
       href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxTables_FI_2025.pdf#page=2
 brackets:
@@ -58,7 +58,7 @@ brackets:
       2021-01-01: 22_125
       2022-01-01: 22_789
       2023-01-01: 23_472
-      2024-01-01: 24_200
+      2024-01-01: 24_176
       2025-01-01: 24_818
     amount:
       2015-01-01: 99

policyengine_us/parameters/gov/states/ar/tax/income/rates/low_income_tax_tables/surviving_spouse/two_or_more_dependents.yaml

@@ -26,9 +26,9 @@ metadata:
     - title: Arkansas Income Tax Instructions, 2021, Low Income Tax Tables
       href: https://www.dfa.arkansas.gov/wp-content/uploads/2021_AR1000F_and_AR1000NR_Instructions.pdf#page=26
     - title: Arkansas Income Tax Instructions, 2023, Low Income Tax Tables
-      href: https://www.dfa.arkansas.gov/wp-content/uploads/2023_AR1000F_and_AR1000NR_Instructions.pdf#page=25
+      href: https://www.dfa.arkansas.gov/wp-content/uploads/2023_AR1000F_and_AR1000NR_Instructions.pdf#page=29
     - title: Arkansas Income Tax Instructions, 2024, Low Income Tax Tables
-      href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=24
+      href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=28
     - title: Arkansas Income Tax Instructions, 2025, Low Income Tax Tables
       href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxTables_FI_2025.pdf#page=2
 brackets:
@@ -58,7 +58,7 @@ brackets:
       2021-01-01: 22_125
       2022-01-01: 22_789
       2023-01-01: 23_472
-      2024-01-01: 24_200
+      2024-01-01: 24_176
       2025-01-01: 24_818
     amount:
       2015-01-01: 99

policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/low_income/ar_low_income_tax_joint.yaml

@@ -334,3 +334,252 @@
         state_code: AR
   output:
     ar_uses_low_income_tax_tables: false
+
+# The 2024 Head of Household/Surviving Spouse with 2 or More Dependents table
+# (2024 AR1000F/AR1000NR instructions, PDF page 28) reads: $0-$24,176 -> $0,
+# $24,177-$24,200 -> $92, $24,201-$24,300 -> $104, $24,301-$24,400 -> $116,
+# $24,401-$24,500 -> $129. The $92 row's threshold was once keyed at $24,200,
+# equal to the next row's, and policyengine-core sums the amounts of brackets
+# with equal thresholds, so $24,201-$24,300 got $196 and the $92 row vanished.
+# One single-member tax unit per income covers every row edge in the range.
+- name: Case 19, 2024 head of household with 2 dependents from $24,100 to $24,401.
+  period: 2024
+  input:
+    people:
+      person1:
+        ar_agi_joint: 24_100
+      person2:
+        ar_agi_joint: 24_176
+      person3:
+        ar_agi_joint: 24_177
+      person4:
+        ar_agi_joint: 24_200
+      person5:
+        ar_agi_joint: 24_201
+      person6:
+        ar_agi_joint: 24_250
+      person7:
+        ar_agi_joint: 24_300
+      person8:
+        ar_agi_joint: 24_301
+      person9:
+        ar_agi_joint: 24_400
+      person10:
+        ar_agi_joint: 24_401
+    tax_units:
+      tax_unit1:
+        members: [person1]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit2:
+        members: [person2]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit3:
+        members: [person3]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit4:
+        members: [person4]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit5:
+        members: [person5]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit6:
+        members: [person6]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit7:
+        members: [person7]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit8:
+        members: [person8]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit9:
+        members: [person9]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit10:
+        members: [person10]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+    households:
+      household:
+        members: [person1, person2, person3, person4, person5, person6, person7, person8, person9, person10]
+        state_code: AR
+  output:
+    ar_low_income_tax_joint: [0, 0, 92, 92, 104, 104, 104, 116, 116, 129]
+
+- name: Case 20, 2024 surviving spouse with 2 dependents from $24,100 to $24,401.
+  period: 2024
+  input:
+    people:
+      person1:
+        ar_agi_joint: 24_100
+      person2:
+        ar_agi_joint: 24_176
+      person3:
+        ar_agi_joint: 24_177
+      person4:
+        ar_agi_joint: 24_200
+      person5:
+        ar_agi_joint: 24_201
+      person6:
+        ar_agi_joint: 24_250
+      person7:
+        ar_agi_joint: 24_300
+      person8:
+        ar_agi_joint: 24_301
+      person9:
+        ar_agi_joint: 24_400
+      person10:
+        ar_agi_joint: 24_401
+    tax_units:
+      tax_unit1:
+        members: [person1]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit2:
+        members: [person2]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit3:
+        members: [person3]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit4:
+        members: [person4]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit5:
+        members: [person5]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit6:
+        members: [person6]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit7:
+        members: [person7]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit8:
+        members: [person8]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit9:
+        members: [person9]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit10:
+        members: [person10]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+    households:
+      household:
+        members: [person1, person2, person3, person4, person5, person6, person7, person8, person9, person10]
+        state_code: AR
+  output:
+    ar_low_income_tax_joint: [0, 0, 92, 92, 104, 104, 104, 116, 116, 129]
+
+- name: Case 21, 2024 head of household and surviving spouse with 2 dependents in the last table rows.
+  period: 2024
+  input:
+    people:
+      person1:
+        ar_agi_joint: 28_100
+      person2:
+        ar_agi_joint: 28_101
+      person3:
+        ar_agi_joint: 28_200
+      person4:
+        ar_agi_joint: 28_100
+      person5:
+        ar_agi_joint: 28_101
+      person6:
+        ar_agi_joint: 28_200
+    tax_units:
+      tax_unit1:
+        members: [person1]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit2:
+        members: [person2]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit3:
+        members: [person3]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit4:
+        members: [person4]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit5:
+        members: [person5]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+      tax_unit6:
+        members: [person6]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+    households:
+      household:
+        members: [person1, person2, person3, person4, person5, person6]
+        state_code: AR
+  output:
+    # $28,001-$28,100 -> $575; $28,101-$28,200 -> $588.
+    ar_low_income_tax_joint: [575, 588, 588, 575, 588, 588]
+
+- name: Case 22, 2024 head of household and surviving spouse with 2 dependents above the $28,200 cutoff.
+  period: 2024
+  input:
+    people:
+      person1:
+        ar_agi_joint: 28_201
+      person2:
+        ar_agi_joint: 28_201
+    tax_units:
+      tax_unit1:
+        members: [person1]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit2:
+        members: [person2]
+        filing_status: SURVIVING_SPOUSE
+        tax_unit_dependents: 2
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    ar_uses_low_income_tax_tables: [false, false]
+
+- name: Case 23, 2024 head of household with 2 dependents pays the table tax before credits.
+  period: 2024
+  input:
+    people:
+      person1:
+        ar_agi_joint: 24_190
+      person2:
+        ar_agi_joint: 24_250
+    tax_units:
+      tax_unit1:
+        members: [person1]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+      tax_unit2:
+        members: [person2]
+        filing_status: HEAD_OF_HOUSEHOLD
+        tax_unit_dependents: 2
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    ar_low_income_tax_joint: [92, 104]
+    ar_income_tax_before_non_refundable_credits_joint: [92, 104]

policyengine_us/tests/policy/baseline/gov/states/ar/tax/income/low_income/test_ar_low_income_tax_tables.py

@@ -0,0 +1,64 @@
+"""Invariants of the Arkansas low-income tax tables, checked at every integer AGI.
+
+`ar_low_income_tax_joint` evaluates these scales with `right=True`. The
+published tables charge more tax at higher AGI until a cutoff, above which
+filers use the regular tax table (encoded as an infinite amount). The head of
+household and surviving spouse files encode the same published column
+("Filing Status 3 or 6"), so they must agree. A 2024 data error broke the
+first invariant: two brackets shared a threshold, core summed them, and the
+table charged $196 at $24,201-$24,300 and then $116 at $24,301-$24,400.
+"""
+
+import numpy as np
+import pytest
+from policyengine_core.parameters import ParameterScale
+
+from policyengine_us.system import system
+
+TABLES = system.parameters.gov.states.ar.tax.income.rates.low_income_tax_tables
+SCALES = {
+    node.name.removeprefix(TABLES.name + "."): node
+    for node in TABLES.get_descendants()
+    if isinstance(node, ParameterScale)
+}
+YEARS = range(2015, 2031)
+
+
+def _tax_by_integer_agi(scale, year):
+    at_instant = scale(f"{year}-01-01")
+    top = max(t for t in at_instant.thresholds if np.isfinite(t))
+    agi = np.arange(0, int(top) + 2)
+    return at_instant.calc(agi, right=True)
+
+
+def test_tables_cover_every_filing_status_and_dependent_tier():
+    assert sorted(SCALES) == [
+        "head_of_household.no_or_one_dependent",
+        "head_of_household.two_or_more_dependents",
+        "joint.no_or_one_dependent",
+        "joint.two_or_more_dependents",
+        "single",
+        "surviving_spouse.no_or_one_dependent",
+        "surviving_spouse.two_or_more_dependents",
+    ]
+
+
+@pytest.mark.parametrize("year", YEARS)
+@pytest.mark.parametrize("table", sorted(SCALES))
+def test_tax_rises_with_agi_until_the_cutoff(table, year):
+    tax = _tax_by_integer_agi(SCALES[table], year)
+    finite = np.isfinite(tax)
+
+    assert finite[0] and not finite[-1]
+    # Once AGI passes the cutoff it never re-enters the table.
+    assert not np.any(finite[1:] & ~finite[:-1])
+    assert np.all(np.diff(tax[finite]) >= 0)
+
+
+@pytest.mark.parametrize("year", YEARS)
+@pytest.mark.parametrize("tier", ["no_or_one_dependent", "two_or_more_dependents"])
+def test_head_of_household_and_surviving_spouse_tables_agree(tier, year):
+    head_of_household = _tax_by_integer_agi(SCALES[f"head_of_household.{tier}"], year)
+    surviving_spouse = _tax_by_integer_agi(SCALES[f"surviving_spouse.{tier}"], year)
+
+    np.testing.assert_array_equal(head_of_household, surviving_spouse)