Let pension-age families make new Housing Benefit claims

[MaxGhenis]

Problem

housing_benefit_eligible required a reported Housing Benefit claim (housing_benefit_reported > 0) and would_claim_uc False for every family. would_claim_uc has no formula and defaults to True outside datasets, so in household (situation) simulations no pension-age renter ever received Housing Benefit:

2026, rent £6,240, State Pension £10,000	main	this PR
Single aged 70, council tenant	HB £0	HB £6,240 (on Guarantee Credit, so income is disregarded)
Single aged 70, council tenant, State Pension £15,000	HB £0	HB £5,696.08 (65% taper)
Couple aged 70 and 68, private renter, rent £9,000	HB £0	HB £8,781.99
Mixed-age couple 70 and 60, private renter	UC £14,243.64, HB £0	unchanged
Single aged 40, council tenant	UC £11,338.80, HB £0	unchanged

The same gate hit the Enhanced FRS: policyengine-uk-data draws would_claim_uc for every benefit unit (pensioners included), so wholly pension-age families who report Housing Benefit lost it whenever that draw came out True (39% of pension-age units).

Law

• New Housing Benefit claims are barred except in listed cases: SI 2014/1230 reg 6A, inserted by SI 2022/752 (it replaced reg 6 and the commencement-order bars). Reg 6A(4) exempts "a single person who has reached the qualifying age for state pension credit" and a couple where both members have. Northern Ireland: SR 2016/226 reg 4A, same wording.
• Universal Credit is not available to them: WRA 2012 s.4(1)(b). Mixed-age couples claim UC jointly (UC Regs 2013 reg 3(2)(a)) and can keep pension-age HB only under the saving for couples entitled to HB or Pension Credit on 14 May 2019 (SI 2019/37 art 4; reg 6A(5)).
• A UC claim ends an existing HB award (reg 8(2A)), except for pension-age claimants (reg 8(2B)).
• The qualifying age for State Pension Credit equals State Pension age for everyone born on or after 6 December 1953 (SPCA 2002 s.1(6)), so is_SP_age is the right test.

All texts read on legislation.gov.uk on 2026-09-29.

Change

housing_benefit_eligible = (pension-age route | continuing award) & (social tenant | LHA-eligible) & capital within the limit, where

• pension-age route: every adult in the benefit unit is over State Pension age. No reported claim needed, and would_claim_uc is ignored.
• continuing award: housing_benefit_reported > 0 and not would_claim_uc (the previous rule, unchanged for working-age and mixed-age families; for mixed-age couples it stands in for the SI 2019/37 saving).

The pension-age test counts the same members as is_uc_eligible (any working-age adult) and is_pension_credit_eligible (all adults over State Pension age), so a family on that route gets no UC; the continuing-award route requires not claiming UC, and universal_credit is defined_for would_claim_uc. So no family receives both (a protected mixed-age couple can be eligible for both, and takes HB). would_claim_housing_benefit is unchanged, so dataset take-up still follows reported claims.

Also corrected: the Housing Benefit docs page (eligibility section; it also said would_claim_housing_benefit is drawn stochastically, but it is a formula), the unused housing_benefit/takeup.yaml description ("only current claimants are eligible (no new claims)"), and the comment in uc_legacy_mutual_exclusion.yaml.

Invariants (property-tested in test_housing_benefit_pension_age_properties.py)

1. 0 ≤ HB ≤ benunit_rent; HB ≤ LHA_cap for LHA tenants; no HB for non-renters or above the capital limit; never HB > 0 and UC > 0 for the same family (a model convention: specified and temporary accommodation is not modelled).
2. With no reported benefits, a family is eligible exactly when every adult is over State Pension age, it rents, and its capital is within the limit; eligible families get their full entitlement.
3. Dataset mode (claims_all_entitled_benefits False): HB > 0 implies reported HB; for families with a working-age adult, eligibility equals the previous continuing-award formula (differential against the old rule).
4. Flipping would_claim_uc never changes a wholly pension-age family's HB.
5. A wholly pension-age family's HB is non-increasing in private pension income.

Six family shapes (single/couple pension-age, mixed-age, single/couple working-age, and a pensioner with an 18–19-year-old dependant), all five tenures, Hypothesis derandomize=True, 10 examples of up to 30 families each (45 s). Invariants 2 and 4 fail on main.

Tests

• New housing_benefit_pension_age_claims.yaml, 12 cases with hand-checked values: single pensioner council tenant (Guarantee Credit passport, HB = rent); pensioner couple capped at LHA (£8,000); a tapered new claim (£9,000 − 0.65 × (£20,000 − £13,312) = £4,652.80); capital over £16,000 without Guarantee Credit (ineligible); capital disregarded on Guarantee Credit; would_claim_uc True does not block; dataset-style reporter with would_claim_uc True is paid; mixed-age couple without and with a continuing award; working-age council tenant (no new claim); pension-age owner-occupier; Northern Ireland. 7 of the 12 fail on main.
• policyengine-core test on all HB, UC/legacy mutual-exclusion and capital YAML files: 30 passed. The scratch run of the full suites on this design (1,264 YAML tests; 314 non-microsimulation pytest tests) found no existing test changes outcome: tests without an age input default to 40.

Dataset impact (Enhanced FRS 2024-25, current weights, real runs of main vs this branch)

2026	main	this PR	change
Housing Benefit	£13.705bn	£14.227bn	+£0.522bn
HB caseload (benefit units)	1,631.9k	1,711.7k	+79.8k
of which wholly pension-age	£13.321bn	£13.843bn	+£0.522bn
mixed-age / working-age HB	£0.200bn / £0.184bn	unchanged	0
UC / Pension Credit / Council Tax Reduction	£79.32bn / £6.99bn / £2.35bn	unchanged	0
Household net income			+£0.522bn (= HB change)
Units with both HB > 0 and UC > 0	0	0	0

Every gainer is a wholly pension-age family that reports HB but drew would_claim_uc True; nobody loses HB. Pension-age families who report no HB still get none in the dataset (take-up there is reported-only), so the new-claim route shows up in household calculations, not in dataset totals.

Caveats: the current weights were calibrated to an OBR HB total while the model paid these families nothing, so a policyengine-uk-data rebuild will move these numbers. The dataset's pension-age HB is already well above DWP's split (GB 2025-26: about £11.35bn in PE vs £7.11bn over Pension Credit age in DWP's Spring 2026 tables, with working-age far below DWP); that mismatch predates this fix and comes from the weights, and this fix widens the pension-age gap by about £0.45bn until the rebuild.

Not in this PR (follow-ups filed separately)

• Working-age Housing Benefit outside specified and temporary accommodation was abolished from 1 July 2026 in GB (SI 2025/1148 art 7, inserted by SI 2026/409) and 1 October 2026 in NI (SR 2025/176 art 7). The continuing-award route is left as is here.
• Specified and temporary accommodation claims (reg 6A(2)) at any age are not modelled.
• The pension-age test uses every adult, like is_uc_eligible and is_pension_credit_eligible; in law it is the claimant and any partner, so a pensioner with an 18–19-year-old dependant is still routed to UC. Replace generic child and adult flags with each programme's legal definitions #1896 moves UC and Pension Credit to is_claimant_or_partner; whichever of the two PRs merges second should move this test with them (and Replace generic child and adult flags with each programme's legal definitions #1896's code-health test flags the is_adult read here).
• Pre-existing HB means-test issues found while testing: the Guarantee Credit passport keys on the calculated guarantee_credit rather than receipt of it; the £5/£10 earnings disregards are uprated with CPI and applied to all income, not only earnings; the LHA cap is applied after the taper rather than to eligible rent.

axiom: SI 2014/1230 reg 6A(4) — TheAxiomFoundation/rulespec-uk#370 queued

🤖 Generated with Claude Code

[MaxGhenis]

Merged at 59560c3 on Max's direct request for this fix (2026-09-29). Gates at merge: all 7 checks passed on the latest run and the PR was MERGEABLE. An independent Opus 5.5 review (Subfleet job 20260930-030326-hb1901-review) returned APPROVE with no blockers; its three wording points (receipt vs eligibility for the HB/UC exclusion, the unmodelled 1 July 2026 working-age abolition, every adult as a proxy for claimant and partner) are applied in 59560c3. Axiom parity: TheAxiomFoundation/rulespec-uk#370 (queued). Coordination with #1896 is noted there.