Nebraska Military Retirement Benefit Exclusion 2022

Fixes PolicyEngine#5011

changelog_entry.yaml

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+

policyengine_us/parameters/gov/states/ne/tax/income/agi/subtractions/military_retirement/fraction.yaml

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+description: Fraction of military retirement benefits allowed as NE AGI subtraction when federal AGI is above threshold (fraction is 1.0 for others).
+values:
+  2022-01-01: 1
+
+metadata:
+  label: fraction of military retirement benefits allowed as NE AGI subtraction when federal AGI is above threshold (fraction is 1.0 for others)
+  unit: /1
+  period: year
+  reference:
+  - title: 2022 NE income tax form and instruction booklet
+    href: https://revenue.nebraska.gov/sites/revenue.nebraska.gov/files/doc/2022_Ne_Individual_Income_Tax_Booklet_8-307-2022_final_8.pdf#page=3
+  - title: Legislative Bill 387
+    href: https://revenue.nebraska.gov/sites/revenue.nebraska.gov/files/doc/info/legislation/2021/LB387.pdf

policyengine_us/tests/policy/baseline/gov/states/ne/tax/income/adjusted_gross_income/ne_military_retirement_subtraction.yaml

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+- name: Test 1, less than agi, for 2022
+  absolute_error_margin: 0.01
+  period: 2022
+  input:
+     adjusted_gross_income: 200_000
+     military_retirement_pay: 30_000
+     state_code: NE
+  output:
+    ne_military_retirement_subtraction: 30_000
+
+- name: Test 2, more than agi, for 2022
+  absolute_error_margin: 0.01
+  period: 2022
+  input:
+     adjusted_gross_income: 20_000
+     military_retirement_pay: 30_000
+     state_code: NE
+  output:
+    ne_military_retirement_subtraction: 20_000

policyengine_us/variables/gov/states/ne/tax/income/adjusted_gross_income/subtractions/ne_military_retirement_substraction.py

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+from policyengine_us.model_api import *
+
+
+class ne_military_retirement_subtraction(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Nebraska military retirement subtraction"
+    unit = USD
+    definition_period = YEAR
+    defined_for = StateCode.NE
+
+    def formula(tax_unit, period, parameters):
+        fagi = tax_unit("adjusted_gross_income", period)
+        p = parameters(
+            period
+        ).gov.states.ne.tax.income.agi.subtractions.military_retirement
+        military_retirement_benefits = add(
+            tax_unit, period, ["military_retirement_pay"]
+        )
+        return min_(military_retirement_benefits * p.fraction, fagi)