Fix DE Filing Status 4 per-column credit allocation

changelog.d/de-per-column-credits.fixed.md

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+Fix Delaware Filing Status 4 to allocate non-refundable credits per-column instead of pooling at the tax-unit level.

policyengine_us/tests/policy/baseline/gov/states/de/tax/income/credits/cdcc/de_cdcc_indv.yaml

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+- name: CDCC locked to lower-income spouse (head has higher income)
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_taxable_income_indv: 50_000
+      person2:
+        is_tax_unit_spouse: true
+        de_taxable_income_indv: 10_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        de_cdcc: 200
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_cdcc_indv: [0, 200]
+
+- name: CDCC locked to lower-income spouse (spouse has higher income)
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_taxable_income_indv: 5_000
+      person2:
+        is_tax_unit_spouse: true
+        de_taxable_income_indv: 60_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        de_cdcc: 200
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_cdcc_indv: [200, 0]
+
+- name: CDCC zero when no childcare expenses
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_taxable_income_indv: 30_000
+      person2:
+        is_tax_unit_spouse: true
+        de_taxable_income_indv: 20_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        de_cdcc: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_cdcc_indv: [0, 0]
+
+- name: tied taxable incomes route CDCC to spouse
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_taxable_income_indv: 30_000
+      person2:
+        is_tax_unit_spouse: true
+        de_taxable_income_indv: 30_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        de_cdcc: 200
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    # On tie, head is "higher", spouse is "lower" -> spouse gets CDCC
+    de_cdcc_indv: [0, 200]
+
+- name: dependent never gets CDCC
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_taxable_income_indv: 50_000
+      person2:
+        is_tax_unit_spouse: true
+        de_taxable_income_indv: 10_000
+      person3:
+        is_tax_unit_dependent: true
+        age: 8
+    tax_units:
+      tax_unit:
+        members: [person1, person2, person3]
+        de_cdcc: 200
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: DE
+  output:
+    de_cdcc_indv: [0, 200, 0]

policyengine_us/tests/policy/baseline/gov/states/de/tax/income/credits/personal/de_aged_personal_credit_indv.yaml

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+- name: only head 60+, spouse under 60
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 65
+        is_tax_unit_head: true
+      person2:
+        age: 50
+        is_tax_unit_spouse: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_aged_personal_credit_indv: [110, 0]
+
+- name: aged dependent does not get credit
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 65
+        is_tax_unit_head: true
+      person2:
+        age: 70
+        is_tax_unit_head: false
+        is_tax_unit_spouse: false
+        is_tax_unit_dependent: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_aged_personal_credit_indv: [110, 0]
+
+- name: both spouses 60+ each get $110 in own column
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 60
+        is_tax_unit_head: true
+      person2:
+        age: 80
+        is_tax_unit_spouse: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_aged_personal_credit_indv: [110, 110]
+
+- name: only spouse 60+
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 55
+        is_tax_unit_head: true
+      person2:
+        age: 65
+        is_tax_unit_spouse: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_aged_personal_credit_indv: [0, 110]
+
+- name: neither spouse 60+
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 40
+        is_tax_unit_head: true
+      person2:
+        age: 50
+        is_tax_unit_spouse: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_aged_personal_credit_indv: [0, 0]

policyengine_us/tests/policy/baseline/gov/states/de/tax/income/credits/personal/de_personal_credit_indv.yaml

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+- name: all credits to higher-capacity column (spouse)
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_income_tax_before_non_refundable_credits_indv: 100
+      person2:
+        is_tax_unit_spouse: true
+        de_income_tax_before_non_refundable_credits_indv: 1_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    # 2 exemptions × $110 = $220, all to spouse (more capacity)
+    de_personal_credit_indv: [0, 220]
+
+- name: all credits to higher-capacity column (head)
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_income_tax_before_non_refundable_credits_indv: 5_000
+      person2:
+        is_tax_unit_spouse: true
+        de_income_tax_before_non_refundable_credits_indv: 100
+      child1:
+        is_tax_unit_dependent: true
+        age: 8
+      child2:
+        is_tax_unit_dependent: true
+        age: 12
+    tax_units:
+      tax_unit:
+        members: [person1, person2, child1, child2]
+    households:
+      household:
+        members: [person1, person2, child1, child2]
+        state_code: DE
+  output:
+    # 4 exemptions × $110 = $440, all to head (more capacity)
+    de_personal_credit_indv: [440, 0, 0, 0]
+
+- name: tied capacity routes to head
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_income_tax_before_non_refundable_credits_indv: 500
+      person2:
+        is_tax_unit_spouse: true
+        de_income_tax_before_non_refundable_credits_indv: 500
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    # On tie, head wins; gets all $220
+    de_personal_credit_indv: [220, 0]

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

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+- name: per-column credits cap at column tax (Line 32)
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_income_tax_before_non_refundable_credits_indv: 50
+        de_personal_credit_indv: 110
+        de_aged_personal_credit_indv: 110
+        de_cdcc_indv: 0
+      person2:
+        is_tax_unit_spouse: true
+        de_income_tax_before_non_refundable_credits_indv: 1_000
+        de_personal_credit_indv: 110
+        de_aged_personal_credit_indv: 110
+        de_cdcc_indv: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    # Head: $50 tax, $220 credits → capped at $50, line33 = $0
+    # Spouse: $1000 tax, $220 credits → line33 = $780
+    de_income_tax_after_non_refundable_credits_indv: [0, 780]
+
+- name: full credit absorption
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_income_tax_before_non_refundable_credits_indv: 500
+        de_personal_credit_indv: 110
+        de_aged_personal_credit_indv: 0
+        de_cdcc_indv: 0
+      person2:
+        is_tax_unit_spouse: true
+        de_income_tax_before_non_refundable_credits_indv: 800
+        de_personal_credit_indv: 110
+        de_aged_personal_credit_indv: 0
+        de_cdcc_indv: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    # Head: $500 - $110 = $390
+    # Spouse: $800 - $110 = $690
+    de_income_tax_after_non_refundable_credits_indv: [390, 690]
+
+- name: both spouses 60+ with very low column taxes (aged credit waste)
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_income_tax_before_non_refundable_credits_indv: 50
+        de_personal_credit_indv: 0
+        de_aged_personal_credit_indv: 110
+        de_cdcc_indv: 0
+      person2:
+        is_tax_unit_spouse: true
+        de_income_tax_before_non_refundable_credits_indv: 80
+        de_personal_credit_indv: 0
+        de_aged_personal_credit_indv: 110
+        de_cdcc_indv: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    # Head: $50 tax, $110 aged → capped at $50, line33 = $0 ($60 wasted)
+    # Spouse: $80 tax, $110 aged → capped at $80, line33 = $0 ($30 wasted)
+    de_income_tax_after_non_refundable_credits_indv: [0, 0]
+
+- name: dependents return zero (only head/spouse have line 33)
+  period: 2025
+  input:
+    people:
+      person1:
+        is_tax_unit_head: true
+        de_income_tax_before_non_refundable_credits_indv: 1_000
+        de_personal_credit_indv: 220
+        de_aged_personal_credit_indv: 0
+        de_cdcc_indv: 0
+      person2:
+        is_tax_unit_dependent: true
+        age: 10
+        de_income_tax_before_non_refundable_credits_indv: 0
+        de_personal_credit_indv: 0
+        de_aged_personal_credit_indv: 0
+        de_cdcc_indv: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: DE
+  output:
+    de_income_tax_after_non_refundable_credits_indv: [780, 0]