[MaxGhenis]

Fixes #2389

Summary

Adds 11 YAML cases for Winter Fuel Payment and PAWHP couples on Income Support, income-based JSA and income-related ESA. Only the two test files and a changelog fragment change; the model doesn't.

Since #2027, is_on_income_support, is_on_income_based_jsa and is_on_income_related_esa are true only for the member of a couple the award is paid to. #2038 reads the two legal concepts separately (partner_receipt_counts):

• paid to P, for SI 2000/729 and SI 2025/969;
• entitled, including through a partner, for SI 2024/869 reg. 2(5) and SSI 2024/351 reg. 7(2), 10(8) and 2A.

Both readings still pay a couple one payment. Until now, no YAML case put a couple on Income Support, and none put an IS, JSA or ESA couple of pensionable age through the one-payment rule.

New cases

Every expected value is worked by hand from the regulation text, which was fetched from legislation.gov.uk on 2026-10-02. Each case cites its regulation in a comment. The exception is the 2025 PAWHP pensionable-age IS couple: its partner's £0 follows the model's documented reading of reg. 9(d), not the text alone (see below).

Case	Scheme, week	Rule	Expected (claimant, partner, lodger)
IS claimant 60, partner 72, lodger 75	WFP 2025	IS not paid to the partner; reg. 4(2)(a) needs a payee of pensionable age; reg. 3(2)	£0, £100, £100
same	WFP 2024	reg. 2(5) couple; reg. 3(c)	£0, £200, £0
JSA claimant 60, partner 81, lodger 75	WFP 2025	reg. 3(5) for the partner, 3(2) for the lodger	£0, £200, £100
same	WFP 2024	reg. 2(5); reg. 3(a)	£0, £300, £0
ESA couple 70 and 72	WFP 2025	reg. 4(2)(a) excludes the partner; reg. 3(1)	£200, £0
JSA couple 70 and 81	WFP 2025	reg. 4(2)(a); reg. 3(3)	£300, £0
IS couple 70 and 72	WFP 2024	reg. 2(5); reg. 4(1)(a)(i); reg. 3(c)	£200, £0
IS claimant 60, partner 72, lodger 75	PAWHP 2024	reg. 7(2) as made; reg. 10(c)	£0, £200, £0
JSA claimant 60, partner 81, lodger 75	PAWHP 2025	reg. 10(8) and 10(4)(a)(i) for the partner; 10(5)(b) for the lodger	£0, £305.10, £101.70
ESA couple 70 and 81	PAWHP 2024	reg. 7(2); reg. 9(1)(d) as made; reg. 10(b)	£300, £0
IS couple 70 and 72	PAWHP 2025	reg. 9(d) as read in pawhp_eligible (see below); reg. 10(4)(b)	£203.40, £0

The JSA cases show the two readings giving different results in the same week. In England in 2025, JSA is not paid to the partner, so the household gets £300. In Scotland, reg. 10(8) treats the partner as entitled, so it gets £406.80.

The 2025 PAWHP pensionable-age couple follows the model's documented reading of reg. 9(d) as substituted by SSI 2025/282. That is an interpretation. For the 2025 week, reg. 10(8) applies its couple rule only within reg. 10, so reg. 9(d) read literally excludes only a member entitled to a relevant benefit in their own right. With the claimant paid first, the literal text would leave the partner eligible for a second £203.40. pawhp_eligible makes one payment per couple, as reg. 7(2) did for the 2024 week. From April 2026, reg. 2A (SSI 2026/170) supports one payment per couple expressly. The case's comment says so, and main's 2025 Pension Credit couple case already relies on the same reading. Both readings are recorded in TheAxiomFoundation/rulespec-uk#420.

The pensionable-age IS, JSA and ESA cases enter the award on the benefit unit. The model reads an award as entered, whatever the claimant's age, so each case tests the one-payment rule for that award.

Mutation check

probes/mutate4.py makes 8 mutants. Each is run against main's two YAML files and against this branch's.

Mutant	main's suite	this branch
exclusion reads only the member's own receipt (the break #2038 fixed after #2027)	5 failures	7
always "paid to" (ignores partner_receipt_counts)	4	11
always "through the couple"	4	7
is_on_income_support true for both members	0 (survives)	5
is_on_income_based_jsa true for both members	1	5
is_on_income_related_esa true for both members	2	4
Income Support dropped from the WFP list	0 (survives)	3
Income Support dropped from the PAWHP list	0 (survives)	2

Tests run

• policyengine-core test on relevant_benefit_receipt.yaml and pawhp.yaml: 67 passed, 11 of them new.
• The winter YAML suites, run on main before this change, including winter_fuel_allowance.yaml and the parametric reforms: 82 passed.
• pytest policyengine_uk/tests/test_winter_heating_payment_properties.py on main: 3 passed. No Python changes.
• The full YAML suite was not run locally, because only these two files change. CI runs it: green on a912177a8.
• On 2026-10-15, a trial merge of this head with current main (cb1770774, which now includes Count the Pension Age Winter Heating Payment in household and HBAI income #2047; Charge the winter fuel payment back through income tax, person by person #2066 is still open) passes all 77 winter YAML cases. The trial merge was aborted, so the head is unchanged.

Review

Independent review r7 (Subfleet review, job 20261012-095108-wfp-couple-cases-r7): APPROVE on a912177a8, with no P2.

• Its P1 is the 2025 reg. 9(d) reading above. It concerns the existing model, not this PR, and is documented in pawhp_eligible and rulespec-uk#420.
• Its optional P3 (a legacy-benefit case where the non-head member reports the award) is not taken: it would change the reviewed head. Main already covers the reported-award payee rule in its Pension Credit claimant-and-lodger cases.
• Its body nits are fixed here.

Impact

None. No model code or parameter changes, so no microsimulation run is needed.

axiom: n/a: tests only, no rule change (the two receipt readings are queued in TheAxiomFoundation/rulespec-uk#420)

🤖 Generated with Claude Code

[MaxGhenis]

Hand-off to the UK hub (from session 257cd086, the #2038 session).

• Owner session 16ff9026, which opened this PR on 10/12, went silent the same day and is gone from the app. I finished it under the fallback rule.
• Head: a912177a81ebdb85acaa4f672aec52a3d3de55d9. Test-only: two YAML files and a changelog fragment, so no model impact.
• Review: r7 (20261012-095108-wfp-couple-cases-r7) APPROVE on this exact head. Its body nits are fixed. Its P1, the 2025 PAWHP reg. 9(d) reading, is the model's documented interpretation and is recorded in Winter Fuel Payment and PAWHP per person: SI 2025/969 regs 1-4; SI 2024/869 regs 2-4; SI 2000/729 regs 2-3; SSI 2024/351 regs 2, 2A, 5-10 (as amended by SSI 2025/282, 2025/100, 2025/195, 2026/170); ITEPA 2003 s.681I (PE parity: policyengine-uk#2038) TheAxiomFoundation/rulespec-uk#420. Its optional P3 was not taken. Report: ~/reviews/winter-heating-per-person-2026-10-02/subfleet/review_r7.md.
• Passed: every check, including Fix evidence after ready-for-review (gh pr checks rc 0); MERGEABLE/CLEAN; not a draft; no change requests. A 2026-10-15 trial merge with main, which now includes Count the Pension Age Winter Heating Payment in household and HBAI income #2047 (Charge the winter fuel payment back through income tax, person by person #2066 is still open), passes all 77 winter YAML cases.
• Pending: the merge queue. Enqueued once, pinned to the head above, at 02:52Z (position 1). Per hub notice 25, it should not be re-enqueued in a loop.
• No dependencies, holds or decisions. Notes: ~/reviews/winter-heating-per-person-2026-10-02/STATUS.md.

[MaxGhenis]

Merged by the merge queue at the handed-off head a912177a8. Landed by the UK hub on the gates.

• Review: the independent r7 review (20261012-095108-wfp-couple-cases-r7) approved this exact head. Its body nits are fixed. Its P1, the 2025 PAWHP reg. 9(d) reading, is the model's documented interpretation and is tracked in Winter Fuel Payment and PAWHP per person: SI 2025/969 regs 1-4; SI 2024/869 regs 2-4; SI 2000/729 regs 2-3; SSI 2024/351 regs 2, 2A, 5-10 (as amended by SSI 2025/282, 2025/100, 2025/195, 2026/170); ITEPA 2003 s.681I (PE parity: policyengine-uk#2038) TheAxiomFoundation/rulespec-uk#420.
• Checks: every check passed on this head. The PR was MERGEABLE/CLEAN with no CHANGES_REQUESTED.
• Scope: test-only (two YAML files and a changelog fragment), so there is no model impact. A 10/15 trial merge with main, including Count the Pension Age Winter Heating Payment in household and HBAI income #2047, passes all 77 winter YAML cases.
• Queue: enqueued once, pinned to this head (02:52Z), per hub notice 25.