Correct pension-age Housing Benefit capital threshold history

changelog.d/hb-capital-threshold-history.fixed.md

@@ -0,0 +1 @@
+- Corrected the ordinary pension-age Housing Benefit capital threshold history to £6,000 before 2 November 2009 and £10,000 thereafter.

policyengine_uk/parameters/gov/dwp/housing_benefit/means_test/capital/pension_age/tariff_income/threshold.yaml

@@ -7,4 +7,13 @@ metadata:
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations 2006 reg. 29(2)
       href: https://www.legislation.gov.uk/uksi/2006/214/regulation/29
 values:
-  2006-04-10: 10000
+  2006-04-10:
+    value: 6000
+    reference:
+      - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations 2006, regulation 29(2)(b) as made
+        href: https://www.legislation.gov.uk/uksi/2006/214/regulation/29/made
+  2009-11-02:
+    value: 10000
+    reference:
+      - title: The Social Security (Deemed Income from Capital) Regulations 2009, regulations 1 and 5
+        href: https://www.legislation.gov.uk/uksi/2009/1676/made

policyengine_uk/tests/test_housing_benefit_capital_threshold_history.py

@@ -0,0 +1,32 @@
+"""Ordinary pension-age HB capital history, before fiscal-year conversion."""
+
+from pathlib import Path
+
+import pytest
+import yaml
+from policyengine_core.parameters import Parameter
+
+PARAMETER_PATH = (
+    Path(__file__).resolve().parents[1]
+    / "parameters/gov/dwp/housing_benefit/means_test/capital/pension_age"
+    / "tariff_income/threshold.yaml"
+)
+
+
+@pytest.mark.parametrize(
+    "instant, expected",
+    [
+        ("2006-04-10", 6000),
+        ("2009-11-01", 6000),
+        ("2009-11-02", 10000),
+        ("2015-04-30", 10000),
+        ("2026-04-30", 10000),
+    ],
+)
+def test_ordinary_threshold_history(instant, expected):
+    # Read the enacted calendar history: annual model conversion starts in 2015.
+    # SI 2006/214 reg 29(2)(b), replaced by SI 2009/1676 regs 1 and 5.
+    data = yaml.safe_load(PARAMETER_PATH.read_text())
+    data["values"] = {str(date): value for date, value in data["values"].items()}
+    threshold = Parameter("pension_age_tariff_threshold", data=data)
+    assert threshold(instant) == expected