Decide Pension Credit minimum guarantee projection basis under SSAA 1992 s.150A #2072

Summary

PolicyEngine UK 2.106.1 stores the correct weekly Pension Credit standard minimum guarantee for single claimants and couples from 2015-16 through 2024-25, and its 2026-27 values of £238.00 and £363.25 match the Great Britain and Northern Ireland uprating orders. Its 2025-26 values are too low, but issue #2083 and pull request #2092 already own that correction. The remaining defect is the projection after 2026-27: both branches use CPI, although section 150A of the Social Security Administration Act 1992 requires the Great Britain amount to increase by at least the Secretary of State's estimate of earnings growth when earnings rise, and Northern Ireland may make a corresponding order. The 2026-27 increase illustrates that the enacted rate may exceed a mechanical earnings floor. A non-negative, one-year-lagged OBR average-earnings index is a defensible forecast proxy, but it is not an enacted 2027-28 rate and cannot predict discretionary uplifts or statutory rounding. Abstract of DWP benefit rate statistics 2025 (Pension Credit worksheet, tables 9 and 10, 2015-16 through 2025-26); The Social Security Benefits Up-rating Order 2025 (article 29(2)); The Social Security Benefits Up-rating Order (Northern Ireland) 2025 (article 29(2)); Benefit and pension rates 2026 to 2027 (Pension Credit table, standard minimum guarantee rows); The Social Security Benefits Up-rating Order 2026 (article 29(2)(a) and (b)); The Social Security Benefits Up-rating Order (Northern Ireland) 2026 (article 29(2)(a)); Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8)); Social Security Administration (Northern Ireland) Act 1992 section 132A (section 132A(1)); A14/2025 Housing Benefit uprating for the financial year ending March 2027 (paragraph 5)

Audited model surface

• Audited release: policyengine-uk 2.106.1
• Audit unit: parameter:gov.dwp.pension_credit.guarantee_credit.minimum_guarantee
• Last model modification: 2026-05-23
• Audit date: 2026-10-05
• Periods reviewed: 2015-16 through 2026-27 explicit values, 2027-28 and later projection behavior
• Jurisdictions: Great Britain, Northern Ireland

Findings and implementation parts

1. From 2027-28, CPI projects both standard minimum guarantee branches below the statutory earnings floor whenever forecast earnings growth exceeds forecast CPI. Using the release's March 2026 OBR assumptions, the first projected increase is about 2.3% under CPI rather than about 3.4% under average earnings.

Sources: Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8)); Social Security Administration (Northern Ireland) Act 1992 section 132A (section 132A(1))

• Create a one-year-lagged OBR average-earnings growth series floored at zero, generate its cumulative index through the existing economic assumptions machinery, and use that index to project both the SINGLE and COUPLE branches after their last enacted value. The zero floor models the absence of a statutory reduction requirement when earnings do not rise. Document that this is a forecast proxy for the statutory minimum, not an enacted future rate, and add focused tests for both relationship types and the non-negative floor. Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8)); Social Security Administration (Northern Ireland) Act 1992 section 132A (section 132A(1)); A14/2025 Housing Benefit uprating for the financial year ending March 2027 (paragraph 5)
  • Add or update reference at policyengine_uk/parameters/gov/dwp/pension_credit/guarantee_credit/minimum_guarantee.yaml → SINGLE.metadata.uprating using Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8)).
  • Add or update reference at policyengine_uk/parameters/gov/dwp/pension_credit/guarantee_credit/minimum_guarantee.yaml → COUPLE.metadata.uprating using Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8)).
  • Add or update reference at policyengine_uk/parameters/gov/dwp/pension_credit/guarantee_credit/minimum_guarantee.yaml → metadata.reference using Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8)); Social Security Administration (Northern Ireland) Act 1992 section 132A (section 132A(1)); A14/2025 Housing Benefit uprating for the financial year ending March 2027 (paragraph 5).

Projection behavior

• gov.dwp.pension_credit.guarantee_credit.minimum_guarantee.SINGLE uses gov.benefit_uprating_cpi after 2026-04-01 (first projected date 2027-04-01): incorrect_in_release. CPI does not enforce the earnings-growth floor that applies to the single standard minimum guarantee when earnings rise. Sources: Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8))
• gov.dwp.pension_credit.guarantee_credit.minimum_guarantee.COUPLE uses gov.benefit_uprating_cpi after 2026-04-01 (first projected date 2027-04-01): incorrect_in_release. CPI does not enforce the earnings-growth floor that applies to the couple standard minimum guarantee when earnings rise. Sources: Social Security Administration Act 1992 section 150A (section 150A(1)(d), (2), (3), (4), and (8))

Uncertainties and exclusions

No 2027-28 standard minimum guarantee had been enacted or published in an official rates table by 5 October 2026. Section 150A leaves the Secretary of State to estimate the general level of earnings and permits rounding, while government may choose a larger increase; the proposed OBR-based series is therefore a transparent forecast assumption rather than a prediction of the eventual order. Northern Ireland may make a corresponding order rather than being directly bound by the Great Britain formula. The 2025-26 error is deliberately excluded from the proposed correction because issue #2083 and pull request #2092 already own it. Earlier Northern Ireland instruments were not checked individually. This review does not certify Pension Credit additions, income definitions, eligibility, the Savings Credit threshold, or Housing Benefit allowances; the latter are enqueued as cited dependency reviews.