Tighten the Housing Benefit passport tests (follow-up to #2000's review)

changelog.d/hb-passport-review-followups.changed.md

@@ -0,0 +1 @@
+- Tighten the Housing Benefit passport tests: hold Guarantee Credit at nil in the contributory-benefit property control, and base the applicable-income arithmetic fixtures on earnings and working tax credit rather than Child Benefit.

policyengine_uk/tests/policy/baseline/finance/benefit/family/housing_benefit/applicable_income/housing_benefit_applicable_income.yaml

@@ -47,18 +47,20 @@
     housing_benefit_applicable_income: 1_000
 
 - name: Pension contributions halved
+  # SI 2006/213 reg 36(3)(b): half of the pension contributions come off
+  # earnings. 3,250 - 1,500 / 2 = 2,500.
   period: 2025
   input:
     # Benefits
-    child_benefit: 1_000
+    child_benefit: 0
     income_support: 0
     jsa_income: 0
     esa_income: 0
     # Income
-    employment_income: 0
+    employment_income: 3_250
     self_employment_income: 0
     property_income: 0
-    private_pension_income: 2_250
+    private_pension_income: 0
     # Tax
     income_tax: 0
     national_insurance: 0
@@ -71,47 +73,50 @@
     housing_benefit_applicable_income: 2_500
 
 - name: Added Tax and income
+  # Earnings plus working tax credit, which counts in full where Sch 5
+  # para 56 does not apply. 3,250 + 2,000 - 1,500 / 2 = 4,500.
   period: 2025
   input:
     # Benefits
-    child_benefit: 1_000
+    child_benefit: 0
     income_support: 0
     jsa_income: 0
     esa_income: 0
     # Income
-    employment_income: 0
+    employment_income: 3_250
     self_employment_income: 0
-    property_income: 1_000
-    private_pension_income: 2_250
+    property_income: 0
+    private_pension_income: 0
     # Tax
     income_tax: 0
     national_insurance: 0
     # Other 
-    tax_credits: 1_000
+    tax_credits: 2_000
     pension_contributions: 1_500
     housing_benefit_applicable_income_disregard: 0
     housing_benefit_applicable_income_childcare_element: 0
   output:
     housing_benefit_applicable_income: 4_500
 
 - name: Pension contributions capped at 0
+  # Applicable income is floored at nil: 3,250 - 100,000 / 2 < 0.
   period: 2025
   input:
     # Benefits
-    child_benefit: 1_000
+    child_benefit: 0
     income_support: 0
     jsa_income: 0
     esa_income: 0
     # Income
-    employment_income: 0
+    employment_income: 3_250
     self_employment_income: 0
-    property_income: 1_000
-    private_pension_income: 2_250
+    property_income: 0
+    private_pension_income: 0
     # Tax
     income_tax: 0
     national_insurance: 0
     # Other 
-    tax_credits: 1_000
+    tax_credits: 0
     pension_contributions: 100_000
     housing_benefit_applicable_income_disregard: 0
     housing_benefit_applicable_income_childcare_element: 0

policyengine_uk/tests/test_housing_benefit_income_related_benefit_passport_properties.py

@@ -30,7 +30,9 @@
    family in receipt equals the rent whether its members are of working age,
    a mixed-age couple or over State Pension age.
 7. Contributory JSA and ESA are not a passport: moving an amount from
-   income-based to contribution-based JSA or ESA turns the passport off.
+   income-based to contribution-based JSA or ESA turns the passport off, and
+   with no guarantee credit either (which passports a pension-age family in
+   its own right) the family's savings stay its capital.
 """
 
 import numpy as np
@@ -287,13 +289,18 @@ def test_contributory_jsa_and_esa_are_not_a_passport(units, amount):
         if name.startswith("a") and name.endswith("_0"):
             person["jsa_contrib"] = {YEAR: amount}
             person["esa_contrib"] = {YEAR: amount}
+    # A pension-age family can still have its capital disregarded through the
+    # Guarantee Credit passport, so hold that at nil to isolate this one.
+    for name, benunit in contributory["benunits"].items():
+        if name.startswith("b"):
+            benunit["guarantee_credit"] = {YEAR: 0.0}
     sim = Simulation(situation=contributory)
     on_benefit = np.asarray(
         sim.calculate("in_receipt_of_income_support_jsa_ib_or_esa_ir", YEAR)
     )
     assert not on_benefit.any()
     capital = np.asarray(sim.calculate("housing_benefit_assessable_capital", YEAR))
     savings = np.array([unit["savings"] for unit in units])
-    # Without the passport the family's savings count as its capital (no
+    # With neither passport the family's savings count as its capital (no
     # non-dependants here, so no household apportionment).
     assert np.allclose(capital, savings, atol=0.01)