Housing Benefit (pensioner) take-up assumed 100%; DWP measures ~85%

PolicyEngine-UK currently applies full take-up for Housing Benefit, while DWP's official take-up series (Income-related benefits: estimates of take-up, FYE 2024 edition — caseload and expenditure bases, central estimates with lower/upper bounds) measures pensioner Housing Benefit take-up around 85%. Pension Credit take-up IS seeded from this same series (parameters/…/pension_credit takeup.yaml cites it), so HB is the inconsistent case: the identical administrative source covers both benefits, one is consumed and one is ignored.

Effect: HB expenditure and poverty impacts among pensioner renters overstate receipt relative to DWP's measured take-up; any UK safety-net comparison touching HB inherits this.

Suggested treatment consistent with the US take-up-contract doctrine: seed a takeup parameter from the DWP central estimates (sourced administrative series, both caseload and expenditure bases available with bounds), or count-calibrate where caseload facts exist in populace-UK's target surface.

Provenance: DWP series staged with verbatim values at ~/scorecard-harvest/uk_dwp/claims_staged.jsonl (take-up lane, 805 rows, central/lower/upper × caseload/expenditure, FYE2023+FYE2024 editions); identified during the PolicyEngine Scorecard UK comparison work (policyengine-scorecard#3).

🤖 Generated with Claude Code

Read the parameters/.../pension_credit takeup.yaml path cited in the issue, then locate the current Housing Benefit full-take-up setting. Compare the available pensioner Housing Benefit values in claims_staged.jsonl and decide which DWP estimate basis is appropriate. Done means pensioner Housing Benefit take-up is sourced consistently with the DWP series and its expenditure and poverty effects no longer assume universal receipt.