Correct Housing Benefit allowance age-threshold references #2204

Summary

The Housing Benefit allowance age thresholds have the correct values (25 and 18) but cite the unrelated non-dependant deduction provision. Approved plan A1 changes only those references to Schedule 3 paragraph 1 and adds age-boundary regressions; it does not change rates, add inputs, or implement the rest of the Housing Benefit plan. Working-age Housing Benefit applicable amounts (Schedule 3 Part 1: age bands, ESA main-phase exception and children)

Audited model surface

• Audited release: policyengine-uk 2.106.1
• Audit unit: parameter:gov.dwp.housing_benefit.allowances.age_threshold.older
• Last model modification: 2026-01-17
• Explicitly reviewed units:
  • parameter:gov.dwp.housing_benefit.allowances.age_threshold.older — last model modification: 2026-01-17
  • parameter:gov.dwp.housing_benefit.allowances.age_threshold.younger — last model modification: 2026-01-17
• Audit date: 2026-10-09
• Periods reviewed: 2024–25 boundary regressions; age thresholds unchanged
• Jurisdictions: Great Britain

Findings and implementation parts

1. 25; first dated 2019; cites non-dependant regulation 74. Keep 25. Replace the unrelated citation with Schedule 3 paragraph 1. The loader backdates the first value, so absence of a 2015 entry is not itself an unavailable-parameter error.

Sources: Working-age Housing Benefit applicable amounts (Schedule 3 Part 1: age bands, ESA main-phase exception and children)

• Correct the age-threshold reference to Schedule 3 paragraph 1, retaining the enacted threshold. Add focused adult allowance boundary tests and a changelog fragment. Working-age Housing Benefit applicable amounts (Schedule 3 Part 1: age bands, ESA main-phase exception and children)
  • Add or update reference at policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/age_threshold/older.yaml → metadata.reference using Working-age Housing Benefit applicable amounts (Schedule 3 Part 1: age bands, ESA main-phase exception and children).

2. 18; first dated 2019; cites non-dependant regulation 74. Keep 18. Replace the unrelated citation with Schedule 3 paragraph 1. The loader backdates the first value, so absence of a 2015 entry is not itself an unavailable-parameter error.

Sources: Working-age Housing Benefit applicable amounts (Schedule 3 Part 1: age bands, ESA main-phase exception and children)

• Correct the age-threshold reference to Schedule 3 paragraph 1, retaining the enacted threshold. Add focused adult allowance boundary tests and a changelog fragment. Working-age Housing Benefit applicable amounts (Schedule 3 Part 1: age bands, ESA main-phase exception and children)
  • Add or update reference at policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/age_threshold/younger.yaml → metadata.reference using Working-age Housing Benefit applicable amounts (Schedule 3 Part 1: age bands, ESA main-phase exception and children).

Uncertainties and exclusions

Only approved plan A1. Historical pensioner rates, child allowances and other missing components are separate work. No new inputs. Closed #2198/#2196/#2197 remain closed.