Disability benefits: PIP, DLA, Attendance Allowance, Carer's Allowance, disability premiums

[vahid-ahmadi]

Gap

Python has comprehensive disability-benefit modelling:

• policyengine_uk/variables/gov/dwp/pip/ — 16 files: daily-living component, mobility component, eligibility, take-up, transitional rules
• policyengine_uk/variables/gov/dwp/dla/ — 7 files: care + mobility components for under-16s
• Attendance Allowance variables under gov/dwp/
• Carer's Allowance, Carer Element, carer premium
• Disability premiums in income-related benefits (IS, JSA, ESA, HB, CTB)
• DHSC variables for health-related elements

The Rust port has only premium-rate parameters in src/parameters/mod.rs::BenefitParams; no PIP/DLA/AA/CA computation exists.

Why it matters

• The user already has notebooks driven by PIP modelling: nics_pip_analysis*.ipynb, pip_person_level_analysis.csv
• Disability benefits interact with means-tested benefits via premiums and passporting (PIP eligibility unlocks UC LCWRA element, carer element triggered by middle-rate care, etc.) — without them, UC/HB/CTR scoring is wrong for ~6 million claimants
• Reform analyses of PIP eligibility tightening (a frequently-discussed lever) cannot be done

What to port

1. PIP daily-living + mobility components (eligibility from FRS disability flags, take-up)
2. DLA equivalents for under-16s
3. Attendance Allowance for over-state-pension-age
4. Carer's Allowance (incl. earnings test) and carer premium / carer element
5. Disability premiums and how they passport into UC/legacy benefits

Effort

Medium. Mostly look-up logic against FRS variables once eligibility flags are clean. Most computation is rate × eligibility × take-up.

References

• Python: policyengine_uk/variables/gov/dwp/pip/, policyengine_uk/variables/gov/dwp/dla/
• Python params: policyengine_uk/parameters/gov/dwp/pip/, parameters/gov/dwp/dla/
• Rust: src/parameters/mod.rs::BenefitParams (premiums only)