Fix Pension Credit and pension-age Housing Benefit earnings uprating

changelog.d/pension-credit-earnings-uprating.fixed.md

@@ -0,0 +1 @@
+Uprate the Pension Credit standard minimum guarantee and the lower Housing Benefit pension-age personal allowances by the previous May-July earnings increase, meeting the SSAA 1992 s150A earnings floor after the last published rates. Derive projected Savings Credit thresholds from the guarantee and a September-CPI-uprated maximum award, keeping the threshold in force when a reform sets a zero phase-in rate, and the higher pension-age allowances as the guarantee plus that maximum. April 2027's single guarantee rises from £238 to £247.282 before rounding, rather than £243.47.

policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/couple/aged.yaml

@@ -15,15 +15,15 @@ metadata:
   period: week
   unit: currency-GBP
   label: Housing Benefit couple pension-age personal allowance
-  # Not uprated by September CPI: the pension-age personal allowances rose 4.75%
-  # in April 2026 (£244.40 to £256.00 single), when September CPI was 3.8%, and
-  # 2.3% in April 2017, when it was 1.0% (Benefit and pension rates 2026 to
-  # 2027, 2017 to 2018). Keeps the lagged calendar-year CPI projection it had
-  # through gov.benefit_uprating_cpi until its own basis is modelled.
-  uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+  # Not uprated as a whole: the allowance is the Pension Credit standard
+  # minimum guarantee plus the maximum Savings Credit (HB A3/2021), which
+  # rise by earnings and September CPI. create_pension_age_allowances.py
+  # derives the years after the published amounts as that sum.
   reference:
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations 2006 (SI 2006/214), Schedule 3, paragraph 1(2)(b)
       href: https://www.legislation.gov.uk/uksi/2006/214/schedule/3
+    - title: DWP Housing Benefit circular A3/2021, paragraphs 3-5 (the allowance is the standard minimum guarantee plus the maximum Savings Credit)
+      href: https://www.gov.uk/government/publications/housing-benefit-adjudication-circulars-2021/a32021-housing-benefit-person-who-have-attained-the-qualifying-age-for-state-pension-credit-amendment-regulations-2021
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations (Northern Ireland) 2006 (SR 2006/406), Schedule 4, paragraph 1 (the same amounts)
       href: https://www.legislation.gov.uk/nisr/2006/406/schedule/4
     - title: Benefit and pension rates 2024 to 2025 - Policy paper

policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/couple/aged_from_cutoff.yaml

@@ -10,13 +10,10 @@ metadata:
   period: week
   unit: currency-GBP
   label: Housing Benefit couple personal allowance, State Pension age reached from April 2021
-  # Not uprated by September CPI: the post-April 2021 pension-age personal
-  # allowances equal the Pension Credit standard minimum guarantee in every year
-  # from 2021-22 to 2026-27, which is reviewed against earnings under Social
-  # Security Administration Act 1992 s150A(1)(d). Keeps the lagged calendar-year
-  # CPI projection it had through gov.benefit_uprating_cpi until its own basis
-  # is modelled.
-  uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+  # Equal to the Pension Credit standard minimum guarantee in 2021-2026;
+  # project at its earnings floor (SSAA 1992 s150A(2)). The HB allowance is
+  # set in Schedule 3 below.
+  uprating: gov.economic_assumptions.indices.earnings_uprating
   reference:
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) (Amendment) Regulations 2021 (SI 2021/188), regulation 2(3), inserting paragraph 1(2)(c) of Schedule 3 to SI 2006/214 from 1 April 2021
       href: https://www.legislation.gov.uk/uksi/2021/188/regulation/2/made

policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/create_pension_age_allowances.py

@@ -0,0 +1,43 @@
+"""Project the higher pension-age Housing Benefit personal allowances.
+
+For claimants who reached State Pension age before 1 April 2021, SI 2006/214
+Schedule 3 paragraph 1(1)(b) and (2)(b) set a personal allowance made up of
+the Pension Credit standard minimum guarantee plus the maximum Savings Credit
+(DWP circular HB A3/2021, paragraphs 3-5). Every published amount from
+2019-20 to 2026-27 is that sum rounded up to the next 5p. The guarantee rises
+with earnings and the maximum with September CPI, so neither index alone
+projects the allowance. Keep the published allowances and derive later years
+as the guarantee plus the maximum, each already uprated by its own index.
+
+Run after general uprating and before fiscal-year conversion, on both the
+main tree and its baseline copy, as the Savings Credit threshold projection
+is. Reprocessing a reform then reads its changed guarantee and maximum.
+"""
+
+from policyengine_core.parameters import ParameterNode
+
+from policyengine_uk.parameters.gov.dwp.pension_credit.savings_credit.create_savings_credit_threshold import (
+    extend_after_last_stated,
+    last_projected_year,
+)
+
+# The Pension Credit amounts each allowance is built from: a lone parent's
+# are a single person's.
+RELATIONS = {"single": "SINGLE", "couple": "COUPLE", "lone_parent": "SINGLE"}
+
+
+def project_pension_age_allowances(parameters: ParameterNode) -> ParameterNode:
+    """Fill the years after each higher allowance's last stated value."""
+    pc = parameters.gov.dwp.pension_credit
+    allowances = parameters.gov.dwp.housing_benefit.allowances
+    last_year = last_projected_year(parameters)
+    for kind, relation in RELATIONS.items():
+        guarantee = pc.guarantee_credit.minimum_guarantee.children[relation]
+        maximum = pc.savings_credit.maximum.children[relation]
+
+        def derive(sample, previous):
+            return guarantee(sample) + maximum(sample)
+
+        extend_after_last_stated(allowances.children[kind].aged, last_year, derive)
+    allowances.clear_parent_cache()
+    return parameters

policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/lone_parent/aged.yaml

@@ -16,15 +16,15 @@ metadata:
   period: week
   unit: currency-GBP
   label: Housing Benefit lone parent pension-age personal allowance
-  # Not uprated by September CPI: the pension-age personal allowances rose 4.75%
-  # in April 2026 (£244.40 to £256.00 single), when September CPI was 3.8%, and
-  # 2.3% in April 2017, when it was 1.0% (Benefit and pension rates 2026 to
-  # 2027, 2017 to 2018). Keeps the lagged calendar-year CPI projection it had
-  # through gov.benefit_uprating_cpi until its own basis is modelled.
-  uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+  # Not uprated as a whole: the allowance is the Pension Credit standard
+  # minimum guarantee plus the maximum Savings Credit (HB A3/2021), which
+  # rise by earnings and September CPI. create_pension_age_allowances.py
+  # derives the years after the published amounts as that sum.
   reference:
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations 2006 (SI 2006/214), Schedule 3, paragraph 1(1)(b)
       href: https://www.legislation.gov.uk/uksi/2006/214/schedule/3
+    - title: DWP Housing Benefit circular A3/2021, paragraphs 3-5 (the allowance is the standard minimum guarantee plus the maximum Savings Credit)
+      href: https://www.gov.uk/government/publications/housing-benefit-adjudication-circulars-2021/a32021-housing-benefit-person-who-have-attained-the-qualifying-age-for-state-pension-credit-amendment-regulations-2021
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations (Northern Ireland) 2006 (SR 2006/406), Schedule 4, paragraph 1 (the same amounts)
       href: https://www.legislation.gov.uk/nisr/2006/406/schedule/4
     - title: Benefit and pension rates 2024 to 2025 - Policy paper

policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/lone_parent/aged_from_cutoff.yaml

@@ -10,13 +10,10 @@ metadata:
   period: week
   unit: currency-GBP
   label: Housing Benefit lone parent personal allowance, State Pension age reached from April 2021
-  # Not uprated by September CPI: the post-April 2021 pension-age personal
-  # allowances equal the Pension Credit standard minimum guarantee in every year
-  # from 2021-22 to 2026-27, which is reviewed against earnings under Social
-  # Security Administration Act 1992 s150A(1)(d). Keeps the lagged calendar-year
-  # CPI projection it had through gov.benefit_uprating_cpi until its own basis
-  # is modelled.
-  uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+  # Equal to the Pension Credit standard minimum guarantee in 2021-2026;
+  # project at its earnings floor (SSAA 1992 s150A(2)). The HB allowance is
+  # set in Schedule 3 below.
+  uprating: gov.economic_assumptions.indices.earnings_uprating
   reference:
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) (Amendment) Regulations 2021 (SI 2021/188), regulation 2(3), inserting paragraph 1(1)(c) of Schedule 3 to SI 2006/214 from 1 April 2021
       href: https://www.legislation.gov.uk/uksi/2021/188/regulation/2/made

policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/single/aged.yaml

@@ -15,15 +15,15 @@ metadata:
   period: week
   unit: currency-GBP
   label: Housing Benefit single pension-age personal allowance
-  # Not uprated by September CPI: the pension-age personal allowances rose 4.75%
-  # in April 2026 (£244.40 to £256.00 single), when September CPI was 3.8%, and
-  # 2.3% in April 2017, when it was 1.0% (Benefit and pension rates 2026 to
-  # 2027, 2017 to 2018). Keeps the lagged calendar-year CPI projection it had
-  # through gov.benefit_uprating_cpi until its own basis is modelled.
-  uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+  # Not uprated as a whole: the allowance is the Pension Credit standard
+  # minimum guarantee plus the maximum Savings Credit (HB A3/2021), which
+  # rise by earnings and September CPI. create_pension_age_allowances.py
+  # derives the years after the published amounts as that sum.
   reference:
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations 2006 (SI 2006/214), Schedule 3, paragraph 1(1)(b)
       href: https://www.legislation.gov.uk/uksi/2006/214/schedule/3
+    - title: DWP Housing Benefit circular A3/2021, paragraphs 3-5 (the allowance is the standard minimum guarantee plus the maximum Savings Credit)
+      href: https://www.gov.uk/government/publications/housing-benefit-adjudication-circulars-2021/a32021-housing-benefit-person-who-have-attained-the-qualifying-age-for-state-pension-credit-amendment-regulations-2021
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) Regulations (Northern Ireland) 2006 (SR 2006/406), Schedule 4, paragraph 1 (the same amounts)
       href: https://www.legislation.gov.uk/nisr/2006/406/schedule/4
     - title: Benefit and pension rates 2024 to 2025 - Policy paper

policyengine_uk/parameters/gov/dwp/housing_benefit/allowances/single/aged_from_cutoff.yaml

@@ -10,13 +10,10 @@ metadata:
   period: week
   unit: currency-GBP
   label: Housing Benefit single personal allowance, State Pension age reached from April 2021
-  # Not uprated by September CPI: the post-April 2021 pension-age personal
-  # allowances equal the Pension Credit standard minimum guarantee in every year
-  # from 2021-22 to 2026-27, which is reviewed against earnings under Social
-  # Security Administration Act 1992 s150A(1)(d). Keeps the lagged calendar-year
-  # CPI projection it had through gov.benefit_uprating_cpi until its own basis
-  # is modelled.
-  uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+  # Equal to the Pension Credit standard minimum guarantee in 2021-2026;
+  # project at its earnings floor (SSAA 1992 s150A(2)). The HB allowance is
+  # set in Schedule 3 below.
+  uprating: gov.economic_assumptions.indices.earnings_uprating
   reference:
     - title: The Housing Benefit (Persons who have attained the qualifying age for state pension credit) (Amendment) Regulations 2021 (SI 2021/188), regulation 2(3), inserting paragraph 1(1)(c) of Schedule 3 to SI 2006/214 from 1 April 2021
       href: https://www.legislation.gov.uk/uksi/2021/188/regulation/2/made

policyengine_uk/parameters/gov/dwp/pension_credit/README.md

@@ -1 +1,26 @@
 # Pension Credit
+
+After the last published rates, the standard minimum guarantee rises each
+April with the previous May-July total-pay average weekly earnings increase,
+using the same statutory input and published precision as the State Pension
+triple lock. This models the earnings minimum in
+[SSAA 1992 s150A(2)](https://www.legislation.gov.uk/ukpga/1992/5/section/150A),
+with no decrease when earnings fall. There is no CPI or 2.5% floor in this
+projection. The three lower Housing Benefit pension-age personal
+allowances, which equal the guarantee, follow the same increase.
+
+The Savings Credit maximum rises with September CPI, following
+[HCWS1101](https://questions-statements.parliament.uk/written-statements/detail/2025-11-26/hcws1101).
+Projected thresholds are derived after uprating:
+`threshold = standard minimum guarantee - maximum / phase_in`.
+At the 60% phase-in rate, this ensures that the formula's maximum award
+follows prices even when the guarantee follows earnings. Published
+thresholds are retained, including their rounding. A zero phase-in rate pays
+no Savings Credit at any threshold, so that year keeps the threshold in force
+before it.
+
+The three higher Housing Benefit pension-age personal allowances, for those
+who reached State Pension age before April 2021, are the guarantee plus the
+maximum Savings Credit (HB A3/2021). After their published amounts they are
+derived as that sum, so the guarantee part follows earnings and the maximum
+follows September CPI.

policyengine_uk/parameters/gov/dwp/pension_credit/guarantee_credit/minimum_guarantee.yaml

@@ -14,12 +14,9 @@ SINGLE:
     2025-04-01: 227.1
     2026-04-01: 238
   metadata:
-    # Not uprated by September CPI: the standard minimum guarantee is reviewed
-    # against earnings under Social Security Administration Act 1992 s150A(1)(d)
-    # (4.8% in April 2026, written statement HCWS1101). Keeps the lagged
-    # calendar-year CPI projection it had through gov.benefit_uprating_cpi until
-    # its own basis is modelled.
-    uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+    # Project at the earnings floor in Social Security Administration Act 1992
+    # s150A(2), using the same May-July AWE input as the State Pension review.
+    uprating: gov.economic_assumptions.indices.earnings_uprating
 COUPLE:
   values:
     2015-04-06: 230.85
@@ -35,18 +32,17 @@ COUPLE:
     2025-04-01: 346.6
     2026-04-01: 363.25
   metadata:
-    # Not uprated by September CPI: the standard minimum guarantee is reviewed
-    # against earnings under Social Security Administration Act 1992 s150A(1)(d)
-    # (4.8% in April 2026, written statement HCWS1101). Keeps the lagged
-    # calendar-year CPI projection it had through gov.benefit_uprating_cpi until
-    # its own basis is modelled.
-    uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+    # Project at the earnings floor in Social Security Administration Act 1992
+    # s150A(2), using the same May-July AWE input as the State Pension review.
+    uprating: gov.economic_assumptions.indices.earnings_uprating
 metadata:
   period: week
   label: Pension Credit minimum guarantee
   unit: currency-GBP
   propagate_metadata_to_children: true
   reference:
+    - title: Social Security Administration Act 1992, section 150A(2)
+      href: https://www.legislation.gov.uk/ukpga/1992/5/section/150A
     - title: The State Pension Credit Regulations 2002 reg. 6
       href: https://www.legislation.gov.uk/uksi/2002/1792/regulation/6/2021-04-12
     - title: Benefit and pension rates 2026 to 2027

policyengine_uk/parameters/gov/dwp/pension_credit/savings_credit/create_savings_credit_threshold.py

@@ -0,0 +1,69 @@
+"""Project Savings Credit thresholds from the guarantee and maximum award.
+
+The standard minimum guarantee rises with earnings, while the Savings Credit
+maximum rises with September CPI (HCWS1101). Under the 60% phase-in rule,
+maximum = phase_in * (standard minimum guarantee - threshold), so the
+threshold is the guarantee less maximum / phase_in. Keep the published
+thresholds, including their rounding, and derive only subsequent years.
+
+A zero phase-in rate pays no Savings Credit at any threshold, and the
+maximum fixes none, so a year with a zero rate keeps the threshold in force
+before it.
+
+Run after general uprating and before fiscal-year conversion, on both the
+main tree and its baseline copy. Reprocessing a reform then reads its changed
+guarantee, maximum and phase-in rate.
+"""
+
+from typing import Any, Callable
+
+from policyengine_core.parameters import Parameter, ParameterNode
+from policyengine_core.parameters.parameter_at_instant import ParameterAtInstant
+
+
+def last_projected_year(parameters: ParameterNode) -> int:
+    """The last year of the earnings index, which the projections run to."""
+    index = parameters.gov.economic_assumptions.indices.earnings_uprating
+    return max(int(entry.instant_str[:4]) for entry in index.values_list)
+
+
+def extend_after_last_stated(
+    parameter: Parameter,
+    last_year: int,
+    derive: Callable[[str, Any], Any],
+) -> None:
+    """Add a value for each year after the parameter's last stated value.
+
+    ``derive(sample, previous)`` gives the year's value from the other
+    parameters at its 30 April ``sample``; ``previous`` is the value in force
+    before it. Each value applies from 1 January, as uprating's do.
+    """
+    last = max(parameter.values_list, key=lambda entry: entry.instant_str)
+    previous = last.value
+    for year in range(int(last.instant_str[:4]) + 1, last_year + 1):
+        previous = derive(f"{year}-04-30", previous)
+        parameter.values_list.append(
+            ParameterAtInstant(parameter.name, f"{year}-01-01", data=previous)
+        )
+    parameter.values_list.sort(key=lambda entry: entry.instant_str, reverse=True)
+    parameter.mark_as_modified()
+
+
+def project_savings_credit_threshold(parameters: ParameterNode) -> ParameterNode:
+    """Fill the years after each threshold's last stated value."""
+    pc = parameters.gov.dwp.pension_credit
+    sc = pc.savings_credit
+    last_year = last_projected_year(parameters)
+    for relation, threshold in sc.threshold.children.items():
+        guarantee = pc.guarantee_credit.minimum_guarantee.children[relation]
+        maximum = sc.maximum.children[relation]
+
+        def derive(sample, previous):
+            phase_in = sc.rate.phase_in(sample)
+            if phase_in == 0:
+                return previous
+            return guarantee(sample) - maximum(sample) / phase_in
+
+        extend_after_last_stated(threshold, last_year, derive)
+    sc.threshold.clear_parent_cache()
+    return parameters

policyengine_uk/parameters/gov/dwp/pension_credit/savings_credit/maximum.yaml

@@ -0,0 +1,18 @@
+description: Maximum weekly Savings Credit, used to derive projected income thresholds.
+SINGLE:
+  values:
+    2026-04-01: 17.96
+COUPLE:
+  values:
+    2026-04-01: 20.10
+metadata:
+  unit: currency-GBP
+  period: week
+  label: Pension Credit Savings Credit maximum
+  uprating: gov.benefit_uprating_cpi
+  propagate_metadata_to_children: true
+  reference:
+    - title: Benefit and pension rates 2026 to 2027 (DWP, gov.uk), Pension Credit
+      href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2026-to-2027/proposed-benefit-and-pension-rates-2026-to-2027#pension-credit
+    - title: Statutory Review of State Pension and Benefit Rates 2026/27, HCWS1101 (Savings Credit maximum increases by September CPI)
+      href: https://questions-statements.parliament.uk/written-statements/detail/2025-11-26/hcws1101

policyengine_uk/parameters/gov/dwp/pension_credit/savings_credit/threshold.yaml

@@ -34,11 +34,9 @@ COUPLE:
 metadata:
   unit: currency-GBP
   period: week
-  # Not uprated by September CPI: the threshold rose 4.9% in April 2026, when
-  # September CPI was 3.8% (Benefit and pension rates 2026 to 2027). Keeps the
-  # lagged calendar-year CPI projection it had through gov.benefit_uprating_cpi
-  # until its own basis is modelled.
-  uprating: gov.economic_assumptions.indices.obr.lagged_cpi
+  # Projected after uprating by create_savings_credit_threshold.py:
+  # standard minimum guarantee - Savings Credit maximum / phase-in rate.
+  # Published thresholds keep their own rounding; only projections are derived.
   propagate_metadata_to_children: true
   reference:
     - title: The State Pension Credit Regulations 2002 reg. 7