Income Support eligibility reads benefit-unit members who are neither claimant nor partner #2023

income_support_eligible (policyengine_uk/variables/gov/dwp/income_support_eligible.py) applies three conditions to every member of the benefit unit. SSCBA 1992 s.124(1) names only the claimant and, for some conditions, the partner. A member who is neither (for example a non-dependent adult) changes eligibility:

• (aa) none_SP_age = ~benunit.any(benunit.members("is_SP_age", period)) bars the claim if any member is over state pension age. s.124(1)(aa): "he has not attained the qualifying age for state pension credit" (the claimant).
• (h) has_esa_income = benunit("esa_income", period) > 0, and esa_income sums every member's esa_income_reported. s.124(1)(h): "he is not entitled to an employment and support allowance and, if he is a member of a couple, the other member of the couple is not entitled to an income-related employment and support allowance".
• Existing award. already_claiming = add(benunit, period, ["income_support_reported"]) > 0 is satisfied by any member's report. No new claim can be made (UC (Transitional Provisions) Regs 2014 reg 6A(1)), so the award must be the claimant's.

Synthetic examples: a caring single claimant aged 40 who reports Income Support is not eligible once the benefit unit also holds an adult aged 70, or an adult reporting income-related ESA. Both extra adults have is_claimant_or_partner: false. A claimant who reports no Income Support becomes eligible when the extra adult reports it.

Found by the independent review of #2001 (finding 2). The fix is #2013.