From ffe5f9823fdea3e567911cc77e426196448f155b Mon Sep 17 00:00:00 2001 From: Vahid Ahmadi Date: Wed, 27 May 2026 10:55:56 +0200 Subject: [PATCH 1/2] Add DLA and SDA documentation page (#771) Ticks off the DLA and SDA entries in #771's docs-pages todo list. Combined into one page because both are closed-to-new-claims legacy DWP disability benefits with very small modelling surface area: - DLA: two component variables (dla_m, dla_sc), each taking a categorical band from the dataset input and multiplying the weekly rate by WEEKS_IN_YEAR. The eligibility-by-activity scoring is not re-derived because the dataset records bands directly; the relevant population (under-16s and unmigrated working-age recipients) is set by the calibration step in policyengine-uk-data. - SDA: single weekly flat-rate payment, binary eligibility taken from sda_reported, maximum age-related addition assumed (justified because the remaining 2001-frozen caseload skews old). References cover SSCBA 1992 s.68/s.71, the Welfare Reform Acts that closed both schemes to new claims, and the DWP caseload statistics page used for calibration. --- changelog.d/771-disability-legacy-docs.md | 1 + .../gov/dwp/disability-legacy-benefits.md | 74 +++++++++++++++++++ 2 files changed, 75 insertions(+) create mode 100644 changelog.d/771-disability-legacy-docs.md create mode 100644 docs/book/programs/gov/dwp/disability-legacy-benefits.md diff --git a/changelog.d/771-disability-legacy-docs.md b/changelog.d/771-disability-legacy-docs.md new file mode 100644 index 000000000..cec627899 --- /dev/null +++ b/changelog.d/771-disability-legacy-docs.md @@ -0,0 +1 @@ +- Add a documentation page covering Disability Living Allowance (mobility + self-care components, both DLA bands taken from dataset categoricals) and Severe Disablement Allowance (binary read from `sda_reported`, maximum age-related addition assumed); ticks off two more #771 docs-pages entries. diff --git a/docs/book/programs/gov/dwp/disability-legacy-benefits.md b/docs/book/programs/gov/dwp/disability-legacy-benefits.md new file mode 100644 index 000000000..f817c0260 --- /dev/null +++ b/docs/book/programs/gov/dwp/disability-legacy-benefits.md @@ -0,0 +1,74 @@ +# DLA and Severe Disablement Allowance + +PolicyEngine UK models two **legacy** DWP disability benefits alongside +the current PIP (covered in [its own page](./PIP.ipynb)): + +- **Disability Living Allowance (DLA)** — closed to new working-age + claims in April 2013 but still paid to existing recipients and to + children under 16. +- **Severe Disablement Allowance (SDA)** — closed to new claims in + April 2001 and replaced by Incapacity Benefit / ESA / Universal Credit; + legacy recipients continue to receive it. + +Both are non-means-tested and flow into `household_benefits` via +`personal_benefits`. + +## Disability Living Allowance + +DLA has two independent components, each with its own band structure: + +| Component | Bands | Variable | Parameter file | +|-----------|-------|----------|----------------| +| Mobility (`dla_m`) | Higher / Lower / None | `dla_m` | `gov/dwp/dla/mobility/{higher,lower}.yaml` | +| Self-care (`dla_sc`) | Higher / Middle / Lower / None | `dla_sc` | `gov/dwp/dla/self_care/{higher,middle,lower}.yaml` | + +A claimant's band on each component is taken from the dataset inputs +`dla_m_category` and `dla_sc_category` (each an enum on `Person`). For +each band the formula multiplies the published **weekly** rate by +`WEEKS_IN_YEAR` to produce an annual amount; the combined award is + +```python +dla = dla_sc + dla_m +``` + +i.e. a recipient on the higher mobility rate and the higher self-care +rate stacks both, producing the maximum DLA award. + +### Eligibility (informational) + +PolicyEngine doesn't re-derive eligibility for DLA because the dataset +records categorical band assignments rather than the underlying +self-care / mobility activity scores. New claims have been routed to +PIP for working-age claimants since April 2013, so the population that +remains on DLA is overwhelmingly: + +- children under 16 (DLA continues to be available), +- adults who were on DLA on 8 April 2013 and have not yet been migrated + to PIP at reassessment. + +Migration to PIP is handled by the calibration step in +`policyengine-uk-data`, not by a re-derivation here. + +## Severe Disablement Allowance + +SDA is a single weekly flat-rate payment, exposed as the variable `sda`. +Eligibility is treated as binary and read straight from the dataset +input `sda_reported`: + +```python +sda = (sda_reported > 0) * gov.dwp.sda.maximum * WEEKS_IN_YEAR +``` + +The model assumes recipients are entitled to the **maximum** age-related +addition. This is a deliberate simplification: SDA was closed to new +claims in 2001 and the remaining caseload is small and old enough that +nearly all recipients qualify for the highest age-related addition. + +## References + +- DLA primary statute: [Social Security Contributions and Benefits Act 1992 s. 71](https://www.legislation.gov.uk/ukpga/1992/4/section/71). +- DLA closure to new working-age claims: [Welfare Reform Act 2012 Part 4](https://www.legislation.gov.uk/ukpga/2012/5/part/4) and [The Personal Independence Payment (Transitional Provisions) Regulations 2013 (SI 2013/387)](https://www.legislation.gov.uk/uksi/2013/387/contents). +- DWP, [Disability Living Allowance: detailed information](https://www.gov.uk/disability-living-allowance). +- SDA primary statute: [Social Security Contributions and Benefits Act 1992 s. 68](https://www.legislation.gov.uk/ukpga/1992/4/section/68) (since repealed for new claims). +- SDA closure to new claims: [The Welfare Reform and Pensions Act 1999 s. 65](https://www.legislation.gov.uk/ukpga/1999/30/section/65). +- DWP, [DLA and SDA caseload statistics](https://www.gov.uk/government/collections/disability-living-allowance-statistics) used by `policyengine-uk-data` for calibration. From 463f75346971f8ef0d4d420269ca9edbb3730482 Mon Sep 17 00:00:00 2001 From: Vahid Ahmadi Date: Sat, 6 Jun 2026 21:52:15 +0100 Subject: [PATCH 2/2] Fix household_benefits aggregation claim in DLA/SDA docs There is no personal_benefits variable; dla and sda are added directly to the household_benefits adds list. Co-Authored-By: Claude Opus 4.8 (1M context) --- docs/book/programs/gov/dwp/disability-legacy-benefits.md | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/docs/book/programs/gov/dwp/disability-legacy-benefits.md b/docs/book/programs/gov/dwp/disability-legacy-benefits.md index f817c0260..331a5c133 100644 --- a/docs/book/programs/gov/dwp/disability-legacy-benefits.md +++ b/docs/book/programs/gov/dwp/disability-legacy-benefits.md @@ -10,8 +10,9 @@ the current PIP (covered in [its own page](./PIP.ipynb)): April 2001 and replaced by Incapacity Benefit / ESA / Universal Credit; legacy recipients continue to receive it. -Both are non-means-tested and flow into `household_benefits` via -`personal_benefits`. +Both are non-means-tested and are added directly into the +`household_benefits` aggregate (via the `dla` and `sda` variables in its +`adds` list). ## Disability Living Allowance