Statutory sick pay is counted as government spending, but employers fund it #2369

What happens

statutory_sick_pay is in GOV_SPENDING_VARIABLES (policyengine_uk/variables/gov/gov_spending.py), so gov_spending counts it and gov_balance is net of it. But employers pay SSP and get none of it back. The Statutory Sick Pay Percentage Threshold (Revocations, Transitional and Saving Provisions) (Great Britain and Northern Ireland) Order 2014 (S.I. 2014/897, in force 6 April 2014) revoked the scheme that let employers recover SSP. The COVID-19 SSP rebate scheme was temporary.

Statutory maternity and paternity pay are different: employers recover most of them from HMRC.

The question

What should gov_spending mean for employer-funded transfers? The model gives two readings, and each is defensible:

1. Public spending: leave SSP out of gov_spending. It stays in household_benefits, because households do receive it. The code-health test from Count Scottish Child Payment, Healthy Start and the Two Child Limit Payment in government spending #2366 then needs SSP on its NOT_PAID_BY_GOVERNMENT list, with the reason "employers pay statutory sick pay and cannot recover it (S.I. 2014/897)".
2. Transfers in respect of the household: keep it, and document that gov_spending includes it.

Reading 1 makes gov_balance match public finances more closely. Reading 2 keeps current outputs. Found in the GPT-6.1 Sol review of #2365.

This is a methodology choice, so it is queued for a maintainer decision rather than changed in a fix PR.