Require Arkansas joint filing with a negative spouse income and use tax table bands

changelog.d/ar-joint-negative-income-tax-table.fixed.md

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+Require Arkansas married couples to file jointly when either spouse has a negative total income, and compute Arkansas regular income tax from the published tax table bands below the table threshold.

policyengine_us/parameters/gov/states/ar/tax/income/rates/main/tax_table/band_offset.yaml

@@ -0,0 +1,42 @@
+description: Arkansas sets the start of each regular income tax table income band this amount above a multiple of the band width.
+# From $75,000 the table's rows run "As Much As $75,001 But Less Than $75,101",
+# so each band starts $1 above a multiple of $100. The row below them spans
+# $74,900 to $75,001, so the $1 offset starts at $75,000. The 2014 and 2015
+# tables end at $50,000, below this row. Negative net taxable income takes the
+# zero offset; the callers floor the resulting tax at zero.
+metadata:
+  type: single_amount
+  threshold_unit: currency-USD
+  amount_unit: currency-USD
+  period: year
+  label: Arkansas regular income tax table band offset
+  reference:
+  - title: 2016 AR1000F and AR1000NR Instructions, 2016 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/LongBookwTaxTables_2016.pdf#page=50
+  - title: 2017 AR1000F and AR1000NR Instructions, 2017 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/AR1000FandAR1000NRInstructions.pdf#page=50
+  - title: 2018 Arkansas Tax Tables, 2018 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2018_Final_TaxTable_with_Cover_Sheet.pdf#page=8
+  - title: 2019 AR1000F and AR1000NR Instructions, 2019 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2019_AR1000F_and_AR1000NR_Instructions.pdf#page=31
+  - title: 2020 AR1000F and AR1000NR Instructions, 2020 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2020_AR1000F_and_AR1000NR_Instructions.pdf#page=31
+  - title: 2021 AR1000F and AR1000NR Instructions, 2021 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2021_AR1000F_and_AR1000NR_Instructions.pdf#page=31
+  - title: 2022 AR1000F and AR1000NR Instructions, 2022 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2022_AR1000F_and_AR1000NR_Instructions.pdf#page=34
+  - title: 2023 AR1000F and AR1000NR Instructions, 2023 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2023_AR1000F_and_AR1000NR_Instructions.pdf#page=34
+  - title: 2024 AR1000F and AR1000NR Instructions, 2024 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=33
+  - title: 2025 AR1000F and AR1000NR Instructions, 2025 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_AR1000F_and_AR1000NR_Instructions.pdf#page=33
+brackets:
+  - threshold:
+      2014-01-01: -.inf
+    amount:
+      2014-01-01: 0
+  - threshold:
+      2014-01-01: 75_000
+    amount:
+      2014-01-01: 1

policyengine_us/parameters/gov/states/ar/tax/income/rates/main/tax_table/band_width.yaml

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+description: Arkansas sets each income band of the regular income tax table to this width.
+values:
+  2014-01-01: 100
+metadata:
+  unit: currency-USD
+  period: year
+  label: Arkansas regular income tax table band width
+  reference:
+  - title: 2014 AR1000F and AR1000NR Instructions, 2014 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/LongBookwTaxTables_2014.pdf#page=28
+  - title: 2015 Arkansas Tax Tables, 2015 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxTables_2015.pdf#page=4
+  - title: 2016 AR1000F and AR1000NR Instructions, 2016 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/LongBookwTaxTables_2016.pdf#page=46
+  - title: 2017 AR1000F and AR1000NR Instructions, 2017 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/AR1000FandAR1000NRInstructions.pdf#page=46
+  - title: 2018 Arkansas Tax Tables, 2018 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2018_Final_TaxTable_with_Cover_Sheet.pdf#page=4
+  - title: 2019 AR1000F and AR1000NR Instructions, 2019 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2019_AR1000F_and_AR1000NR_Instructions.pdf#page=28
+  - title: 2020 AR1000F and AR1000NR Instructions, 2020 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2020_AR1000F_and_AR1000NR_Instructions.pdf#page=28
+  - title: 2021 AR1000F and AR1000NR Instructions, 2021 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2021_AR1000F_and_AR1000NR_Instructions.pdf#page=28
+  - title: 2022 AR1000F and AR1000NR Instructions, 2022 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2022_AR1000F_and_AR1000NR_Instructions.pdf#page=31
+  - title: 2023 AR1000F and AR1000NR Instructions, 2023 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2023_AR1000F_and_AR1000NR_Instructions.pdf#page=31
+  - title: 2024 AR1000F and AR1000NR Instructions, 2024 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=30
+  - title: 2025 AR1000F and AR1000NR Instructions, 2025 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_AR1000F_and_AR1000NR_Instructions.pdf#page=30

policyengine_us/parameters/gov/states/ar/tax/income/rates/main/tax_table/threshold.yaml

@@ -0,0 +1,62 @@
+description: Arkansas uses the regular income tax table for net taxable income below this amount.
+# Each value is the "But Less Than" bound of the table's last row, where the
+# table's note starts ("For $100,001 and over, your tax is ...").
+# At and above it, two DFA instructions conflict, and the model follows the
+# first:
+# - The Indexed Tax Brackets card gives the bracket formula (rate x income
+#   minus the adjustment) and says a formula "must match the table exactly"
+#   (2021 card, file p.1; 2024 card, file p.2). The model applies this
+#   formula to the exact income.
+# - The note under each table's last row adds the top rate to the last row's
+#   tax: "For $100,001 and over, your tax is $3,811 + 3.9% of the excess over
+#   $100,000" (2024 table, file p.34); "$3,809 + 3.9%" (2025 table, file p.34).
+# The note gives less tax than the formula, by the same amount for every
+# income at or above the threshold: $3.19 (2014), $3.69 (2015), $3.36 (2016),
+# $3.46 (2017), $3.26 (2018), $3.36 (2019), $3.30 (2020), $2.50 (2021),
+# $2.80 (2022), $2.30 (2023), $1.60 (2024) and $1.70 (2025). Neither source
+# settles which applies above the table, where there are no rows for the
+# card's formula to match, so keep the formula unless a DFA source does.
+values:
+  2014-01-01: 50_000
+  2016-01-01: 86_001
+  2019-01-01: 87_001
+  2020-01-01: 88_001
+  2021-01-01: 91_001
+  2022-01-01: 94_001
+  2023-01-01: 100_001
+  # No Regular Income Tax Table has been published for 2026 or later, so the
+  # model carries this value forward and applies the table method to the
+  # 2026+ statutory schedules below it.
+metadata:
+  unit: currency-USD
+  period: year
+  label: Arkansas regular income tax table threshold
+  reference:
+  - title: 2014 AR1000F and AR1000NR Instructions, 2014 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/LongBookwTaxTables_2014.pdf#page=30
+  - title: 2015 Arkansas Tax Tables, 2015 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxTables_2015.pdf#page=6
+  - title: 2016 AR1000F and AR1000NR Instructions, 2016 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/LongBookwTaxTables_2016.pdf#page=50
+  - title: 2017 AR1000F and AR1000NR Instructions, 2017 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/AR1000FandAR1000NRInstructions.pdf#page=50
+  - title: 2018 Arkansas Tax Tables, 2018 Regular Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2018_Final_TaxTable_with_Cover_Sheet.pdf#page=8
+  - title: 2019 AR1000F and AR1000NR Instructions, 2019 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2019_AR1000F_and_AR1000NR_Instructions.pdf#page=32
+  - title: 2020 AR1000F and AR1000NR Instructions, 2020 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2020_AR1000F_and_AR1000NR_Instructions.pdf#page=32
+  - title: 2021 AR1000F and AR1000NR Instructions, 2021 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2021_AR1000F_and_AR1000NR_Instructions.pdf#page=32
+  - title: 2022 AR1000F and AR1000NR Instructions, 2022 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2022_AR1000F_and_AR1000NR_Instructions.pdf#page=35
+  - title: 2023 AR1000F and AR1000NR Instructions, 2023 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2023_AR1000F_and_AR1000NR_Instructions.pdf#page=35
+  - title: 2024 AR1000F and AR1000NR Instructions, 2024 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=34
+  - title: 2025 AR1000F and AR1000NR Instructions, 2025 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2025_AR1000F_and_AR1000NR_Instructions.pdf#page=34
+  - title: 2021 Indexed Tax Brackets (a formula must match the table exactly)
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxBrackets_2021.pdf#page=1
+  - title: 2024 Indexed Tax Brackets (a formula must match the table exactly)
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_TaxBrackets.pdf#page=2

policyengine_us/parameters/gov/states/ar/tax/income/rates/main/tax_table/whole_dollar_midpoint.yaml

@@ -0,0 +1,27 @@
+description: Arkansas uses the midpoint of the whole-dollar incomes in each regular income tax table band if this is true, and the midpoint of the band's bounds otherwise.
+# DFA computes each row at the band midpoint and rounds to whole dollars. At
+# the midpoint of the bounds ($14,850 for the $14,800-$14,900 row), some rows
+# land exactly on 50 cents. Through 2021 the table rounds these up (2021:
+# $40,250 x 5.9% - $797.25 = $1,577.50, printed as $1,578). From 2022 it
+# rounds them down (2022: $24,750 x 4.9% - $628.25 = $584.50, printed as $584).
+# That matches evaluating at the midpoint of the whole-dollar incomes the row
+# covers ($24,700 to $24,799: $24,749.50 x 4.9% - $628.25 = $584.48, or $584).
+# With these settings every 2014-2025 row matches the published table.
+values:
+  2014-01-01: false
+  2022-01-01: true
+  # No Regular Income Tax Table has been published for 2026 or later, so the
+  # model carries this value forward.
+metadata:
+  unit: bool
+  period: year
+  label: Arkansas regular income tax table whole-dollar midpoint
+  reference:
+  - title: 2021 Indexed Tax Brackets (the calculations in the table are made at the midpoint of each income level)
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/TaxBrackets_2021.pdf#page=1
+  - title: 2021 AR1000F and AR1000NR Instructions, 2021 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2021_AR1000F_and_AR1000NR_Instructions.pdf#page=30
+  - title: 2022 AR1000F and AR1000NR Instructions, 2022 Regular Income Tax Table
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2022_AR1000F_and_AR1000NR_Instructions.pdf#page=32
+  - title: 2024 Indexed Tax Brackets (the calculations in the table are made at the midpoint of each income level)
+    href: https://www.dfa.arkansas.gov/wp-content/uploads/2024_TaxBrackets.pdf#page=2

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

@@ -231,3 +231,219 @@
         state_code: AR
   output:
     ar_files_separately: false
+
+# A married couple must file jointly if either spouse had a total negative
+# income: "IF ONE SPOUSE HAD A TOTAL NEGATIVE INCOME, YOU MUST FILE MARRIED
+# FILING JOINTLY." (2024 AR1000F/AR1000NR instructions, Filing Status 4, p.12:
+# https://www.dfa.arkansas.gov/wp-content/uploads/2024_AR1000F_and_AR1000NR_Instructions.pdf#page=12;
+# same wording in 2025, p.12).
+- name: Separate tax lower, but the spouse's total income is negative, files jointly
+  period: 2024
+  input:
+    people:
+      person1:
+        ar_income_tax_before_non_refundable_credits_indiv: 0
+        ar_income_tax_before_non_refundable_credits_joint: 100
+        ar_taxable_income_indiv: 50_000
+        ar_net_taxable_income_joint: 50_000
+        ar_gross_income_indiv: 50_000
+      person2:
+        ar_income_tax_before_non_refundable_credits_indiv: 100
+        ar_income_tax_before_non_refundable_credits_joint: 500
+        ar_taxable_income_indiv: 0
+        ar_net_taxable_income_joint: 0
+        ar_gross_income_indiv: -1
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    # Separate tax 100 < joint tax 600, but person2's total income is -1 < 0.
+    ar_files_separately: false
+
+- name: Spouse partnership loss of $10 forces a joint return that costs more (issue 9680)
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 27_850
+      person2:
+        age: 38
+        partnership_s_corp_income: -10
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    ar_gross_income_indiv: [27_850, -10]
+    # Separate path: person1 27,850 - 2,410 = 25,440, 2024 Regular Income Tax
+    # Table row $25,400-$25,500: $584 (p.31); person2 has no taxable income.
+    ar_income_tax_before_non_refundable_credits_indiv: [584, 0]
+    # Separate additional credit: 60 each (25,440 and 0 are below 25,800) = 120,
+    # so the separate path nets 584 - 120 = 464.
+    # Joint path: AGI 27,850 - 10 = 27,840, joint low income table (0-1
+    # dependents) row $27,801-$27,900: $470 (p.29); the joint additional credit
+    # 120 - ceil((27,840 - 25,800) / 100) x 10 phases out to 0, so it nets 470.
+    ar_low_income_tax_joint: [470, 0]
+    # Separate (464) < joint (470), but person2's total income is negative.
+    ar_files_separately: false
+    ar_income_tax_before_non_refundable_credits_unit: 470
+    # 470 - 2 x 29 personal credits = 412
+    ar_non_refundable_credits: 58
+    ar_income_tax: 412
+
+- name: Head partnership loss of $10 also forces a joint return
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        partnership_s_corp_income: -10
+      person2:
+        age: 38
+        employment_income: 27_850
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    ar_gross_income_indiv: [-10, 27_850]
+    ar_income_tax_before_non_refundable_credits_indiv: [0, 584]
+    # Same as above with the spouses swapped: joint 470 - 58 = 412.
+    ar_files_separately: false
+    ar_income_tax: 412
+
+- name: Spouse with zero total income can still file separately (regression)
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 27_850
+      person2:
+        age: 38
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    # Zero is not negative. Separate 584 - 120 = 464 < joint 470 (AGI 27,850,
+    # row $27,801-$27,900), so the couple files separately.
+    ar_files_separately: true
+    ar_income_tax_before_non_refundable_credits_unit: 584
+    # 584 - 58 personal credits - 120 additional credits = 406
+    ar_income_tax: 406
+
+- name: Both spouses with positive income keep the cheaper separate election (regression)
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 40_000
+      person2:
+        age: 38
+        employment_income: 40_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    # Separate: each 40,000 - 2,410 = 37,590, row $37,500-$37,600: $1,055 (p.31).
+    ar_income_tax_before_non_refundable_credits_indiv: [1_055, 1_055]
+    # Joint: 80,000 - 4,820 = 75,180, row $75,101-$75,201: $2,521 (p.33).
+    ar_income_tax_before_non_refundable_credits_joint: [2_521, 0]
+    # Separate 2,110 < joint 2,521; neither total income is negative.
+    ar_files_separately: true
+    ar_income_tax_before_non_refundable_credits_unit: 2_110
+    # 2,110 - 58 = 2,052
+    ar_income_tax: 2_052
+
+- name: Spouse partnership loss of $300 files jointly, where the joint and separate paths tie (issue 9680)
+  # The tie already keeps this couple on the joint path (strict <), so this case
+  # passes without the negative-income rule. The $10 loss cases above isolate
+  # the rule.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 28_450
+      person2:
+        age: 38
+        partnership_s_corp_income: -300
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    # Joint AGI 28,450 - 300 = 28,150, joint low income table row
+    # $28,101-$28,200: $501 (p.29). Separately, person1's 26,040 falls in the
+    # regular row $26,000-$26,100: $606 (p.31), less 45 + 60 of additional
+    # credits = 501, a tie, which keeps the joint return; the negative total
+    # income also requires it.
+    ar_low_income_tax_joint: [501, 0]
+    ar_income_tax_before_non_refundable_credits_indiv: [606, 0]
+    ar_files_separately: false
+    # 501 - 58 = 443
+    ar_income_tax: 443
+
+- name: Spouse capital loss of $500 files jointly, where the joint path is already cheaper
+  # The joint path costs less even without the negative-income rule, so this
+  # case does not isolate the rule. The $10 loss cases above do.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 27_850
+      person2:
+        age: 38
+        short_term_capital_gains: -500
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: AR
+  output:
+    # person2's total income is the -500 capital loss.
+    ar_gross_income_indiv: [27_850, -500]
+    # Separate path: person1 27,850 - 2,410 = 25,440, row $25,400-$25,500:
+    # $584 (p.31), less 60 + 60 of additional credits = 464.
+    ar_income_tax_before_non_refundable_credits_indiv: [584, 0]
+    # Joint path: AGI 27,850 - 500 = 27,350, joint low income table row
+    # $27,301-$27,400: $418 (p.29); the joint additional credit
+    # 120 - ceil((27,350 - 25,800) / 100) x 10 phases out to 0, so it nets 418.
+    ar_low_income_tax_joint: [418, 0]
+    # Joint (418) < separate (464), so the couple files jointly either way.
+    ar_files_separately: false
+    # 418 - 58 = 360
+    ar_income_tax: 360