Exclude joint filing units from the Delaware elderly or disabled exclusion if only one filer is eligible

changelog_entry.yaml

@@ -0,0 +1,4 @@
+- bump: patch
+  changes:
+    fixed:
+    - Among joint filers, limit the Delaware elderly or disabled exclusion to filers with both head and spouse eligible.

policyengine_us/parameters/gov/states/de/tax/income/subtractions/exclusions/elderly_or_disabled/amount.yaml

@@ -1,6 +1,9 @@
 description: Delaware provides this income exclusion to elderly and disabled filers, based on filing status.
+# The joint amount is defined as double of the Single amount, 
+# we encode it as 1/2 of the joint total as we calculate the 
+# amount on a person level
 JOINT:
-  2021-01-01: 4_000
+  2021-01-01: 2_000
 HEAD_OF_HOUSEHOLD:
   2021-01-01: 2_000
 WIDOW:

policyengine_us/tests/policy/baseline/gov/states/de/tax/income/integration.yaml

@@ -123,3 +123,34 @@
         state_fips: 10  # DE
   output:  # expected results from patched TAXSIM35 2024-02-15 version
     de_income_tax: 7_901.98
+
+- name: Tax unit with taxsimid 84350 in e21.its.csv and e21.ots.csv
+  absolute_error_margin: 0.01
+  period: 2021
+  input:
+    people:
+      person1:
+        age: 63
+        employment_income: 128010
+        taxable_interest_income: 5505
+      person2:
+        age: 63
+        employment_income: 2010
+        taxable_interest_income: 5505
+      person3:
+        age: 11
+    tax_units:
+      tax_unit:
+        members: [person1, person2, person3]
+        premium_tax_credit: 0  # not in TAXSIM35
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        snap: 0  # not in TAXSIM35
+        tanf: 0  # not in TAXSIM35
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_fips: 10  # DE
+  output:  # expected results from patched TAXSIM35 2024-03-07 version
+    de_income_tax: 6585.82

policyengine_us/tests/policy/baseline/gov/states/de/tax/income/subtractions/exclusions/de_elderly_or_disabled_income_exclusion.yaml

@@ -0,0 +1,102 @@
+- name: Eligible individual exclusion
+  period: 2023
+  input:
+    filing_status: SEPARATE
+    de_elderly_or_disabled_income_exclusion_eligible_person: true
+  output:
+    de_elderly_or_disabled_income_exclusion: 2_000
+
+- name: Ineligible individual exclusion
+  period: 2023
+  input:
+    filing_status: SEPARATE
+    de_elderly_or_disabled_income_exclusion_eligible_person: false
+  output:
+    de_elderly_or_disabled_income_exclusion: 0
+
+- name: Joint filing status with two eligible people
+  period: 2023
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: true
+      person2:
+        is_tax_unit_spouse: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: true
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_elderly_or_disabled_income_exclusion: [2_000, 2_000]
+
+- name: Joint filing status with one eligible person
+  period: 2023
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: true
+      person2:
+        is_tax_unit_spouse: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: false
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_elderly_or_disabled_income_exclusion: [0, 0]
+
+- name: Joint filing status with two eligible people
+  period: 2023
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: true
+      person2:
+        is_tax_unit_spouse: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: true
+      person3:
+        is_tax_unit_spouse: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: false
+    tax_units:
+      tax_unit:
+        members: [person1, person2, person3]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: DE
+  output:
+    de_elderly_or_disabled_income_exclusion: [2_000, 2_000, 0]
+
+- name: Head of household filing status with one eligible person
+  period: 2023
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: true
+      person2:
+        is_tax_unit_spouse: true
+        de_elderly_or_disabled_income_exclusion_eligible_person: false
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: HEAD_OF_HOUSEHOLD
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_elderly_or_disabled_income_exclusion: [2_000, 0]

policyengine_us/variables/gov/states/de/tax/income/subtractions/exclusions/de_elderly_or_disabled_income_exclusion.py

@@ -11,13 +11,29 @@ class de_elderly_or_disabled_income_exclusion(Variable):
     defined_for = "de_elderly_or_disabled_income_exclusion_eligible_person"
 
     def formula(person, period, parameters):
+        tax_unit = person.tax_unit
         # First get their filing status.
-        filing_status = person.tax_unit(
-            "state_filing_status_if_married_filing_separately_on_same_return",
-            period,
-        )
+        filing_status = tax_unit("filing_status", period)
         p = parameters(
             period
         ).gov.states.de.tax.income.subtractions.exclusions.elderly_or_disabled
 
-        return p.amount[filing_status]
+        # If filing jointly, both spouses have to be eligible.
+        joint = filing_status == filing_status.possible_values.JOINT
+
+        head = person("is_tax_unit_head", period)
+
+        spouse = person("is_tax_unit_spouse", period)
+
+        eligible_person = person(
+            "de_elderly_or_disabled_income_exclusion_eligible_person", period
+        )
+
+        eligible_head_present = tax_unit.any(head & eligible_person)
+
+        eligible_spouse_present = tax_unit.any(spouse & eligible_person)
+
+        eligible_joint_unit = eligible_head_present & eligible_spouse_present
+
+        eligible_unit = where(joint, eligible_joint_unit, eligible_person)
+        return p.amount[filing_status] * eligible_unit