Add protected Housing Benefit family premiums

changelog.d/hb-family-premium.added.md

@@ -0,0 +1 @@
+Added protected Housing Benefit family premiums with jurisdiction-specific closure dates and an explicit pre-assessed historical category.

docs/book/assumptions/housing-benefit-child-allowances.md

@@ -4,7 +4,8 @@ PolicyEngine does not currently calculate ordinary child personal allowances in
 the Housing Benefit applicable amount. This omission applies before, during and
 after the historical two-child restriction. The model calculates an adult
 personal allowance from the benefit unit's composition and age, then adds the
-premiums selected by `benefits_premiums`. It does not calculate an ordinary
+premiums selected by `benefits_premiums`, the child disability premiums and the
+protected family premium. It does not calculate an ordinary
 allowance for either the first two children or additional children. See
 `housing_benefit_applicable_amount` in
 [`policyengine_uk/variables/gov/dwp/housing_benefit/`](https://github.com/PolicyEngine/policyengine-uk/blob/main/policyengine_uk/variables/gov/dwp/housing_benefit/housing_benefit_applicable_amount.py).
@@ -111,8 +112,9 @@ included-child count is one possible interface for that discussion; it is not
 a supported model input. This documentation introduces no claim-history or
 exception inputs and changes no calculation.
 
-Child disability premiums and the protected family premium are separate work
-under [#2221](https://github.com/PolicyEngine/policyengine-uk/issues/2221) and
-[#2223](https://github.com/PolicyEngine/policyengine-uk/issues/2223). This page
+The model adds child disability premiums and the protected family premium
+separately, from
+[#2221](https://github.com/PolicyEngine/policyengine-uk/pull/2221) and
+[#2223](https://github.com/PolicyEngine/policyengine-uk/pull/2223). This page
 does not revive [closed PR #2198](https://github.com/PolicyEngine/policyengine-uk/pull/2198)
 or its associated issues.

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

@@ -1,11 +1,11 @@
 # Housing Benefit
 
 The default `housing_benefit_applicable_amount` calculation includes an adult
-personal allowance and selected premiums. It omits ordinary child personal
-allowances, including in periods when no two-child restriction applied.
+personal allowance, selected adult premiums, child disability premiums and the
+protected family premium. It omits ordinary child personal allowances,
+including in periods when no two-child restriction applied.
 
 See [historical child personal allowances and the deferred implementation](../../../../../docs/book/assumptions/housing-benefit-child-allowances.md)
 for the Great Britain and Northern Ireland rules, individual-child protection,
 Child Tax Credit assessment requirements and the missing historical facts.
-The documentation adds no model input or calculation. Child disability and
-protected family premiums remain separate work.
+The documentation adds no model input or calculation.

policyengine_uk/parameters/gov/dwp/housing_benefit/premiums/family/amount.yaml

@@ -0,0 +1,55 @@
+description: Weekly Housing Benefit ordinary family premium for legally protected awards.
+values:
+  2015-04-01:
+    value: 17.45
+    metadata:
+      reference:
+        title: Housing Benefit 2015 family premium rate
+        href: https://www.legislation.gov.uk/uksi/2015/457/article/17/made
+  2020-04-01:
+    value: 17.6
+    metadata:
+      reference:
+        title: Housing Benefit 2020 family premium rate
+        href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2020-to-2021/benefit-and-pension-rates-2020-to-2021
+  2021-04-01:
+    value: 17.65
+    metadata:
+      reference:
+        title: Housing Benefit 2021 family premium rate
+        href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2021-to-2022/benefit-and-pension-rates-2021-to-2022
+  2022-04-01:
+    value: 17.85
+    metadata:
+      reference:
+        title: Housing Benefit 2022 family premium rate
+        href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2023-to-2024/benefit-and-pension-rates-2023-to-2024
+  2023-04-01:
+    value: 18.53
+    metadata:
+      reference:
+        title: Housing Benefit 2023 family premium rate
+        href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2023-to-2024/benefit-and-pension-rates-2023-to-2024
+  2024-04-01:
+    value: 19.15
+    metadata:
+      reference:
+        title: Housing Benefit 2024 family premium rate
+        href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2024-to-2025/benefit-and-pension-rates-2024-to-2025
+  2025-04-01:
+    value: 19.48
+    metadata:
+      reference:
+        title: Housing Benefit 2025 family premium rate
+        href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2026-to-2027/proposed-benefit-and-pension-rates-2026-to-2027
+  2026-04-01:
+    value: 20.22
+    metadata:
+      reference:
+        title: Housing Benefit 2026 family premium rate
+        href: https://www.gov.uk/government/publications/benefit-and-pension-rates-2026-to-2027/proposed-benefit-and-pension-rates-2026-to-2027
+metadata:
+  unit: currency-GBP
+  period: week
+  label: Housing Benefit protected family premium
+  uprating: gov.benefit_uprating_cpi

policyengine_uk/parameters/gov/dwp/housing_benefit/premiums/family/lone_parent_protected_amount.yaml

@@ -0,0 +1,12 @@
+description: Weekly Housing Benefit family premium for working-age lone-parent awards satisfying the pre-April 1998 protection conditions.
+values:
+  2015-04-01: 22.20
+metadata:
+  unit: currency-GBP
+  period: week
+  label: Housing Benefit historical lone-parent family premium
+  reference:
+    - title: GB working-age Schedule 3 paragraph 3, before abolition, saved by SI 2015/1857
+      href: https://www.legislation.gov.uk/uksi/2006/213/schedule/3/part/2/2015-04-06
+    - title: NI working-age Schedule 4 paragraph 3, before abolition, saved by SR 2016/310
+      href: https://www.legislation.gov.uk/nisr/2006/405/schedule/4/part/II/2015-04-06

policyengine_uk/parameters/gov/dwp/housing_benefit/premiums/family/new_claim_end.yaml

@@ -0,0 +1,21 @@
+description: Legal closure dates for Housing Benefit family premiums on new claims, written as YYYYMMDD numbers, with existing qualifying awards protected.
+great_britain:
+  description: GB new-claim closure date.
+  values:
+    2015-01-01: 20160501
+  metadata:
+    unit: date
+    label: Housing Benefit family premium GB new-claim closure date
+    reference:
+      title: SI 2015/1857 regulations 1, 2 and 4
+      href: https://www.legislation.gov.uk/uksi/2015/1857/made
+northern_ireland:
+  description: NI new-claim closure date.
+  values:
+    2015-01-01: 20160905
+  metadata:
+    unit: date
+    label: Housing Benefit family premium NI new-claim closure date
+    reference:
+      title: SR 2016/310 regulations 1, 3 and 5
+      href: https://www.legislation.gov.uk/nisr/2016/310/made

policyengine_uk/tests/policy/baseline/finance/benefit/family/housing_benefit/housing_benefit_family_premium.yaml

@@ -0,0 +1,220 @@
+# Cases: none; ordinary; historical lone parent; no longer lone parent; no child.
+- name: ENGLAND pension regime false protected family categories
+  period: 2026
+  absolute_error_margin: 0.02
+  input:
+    country: [ENGLAND, ENGLAND, ENGLAND, ENGLAND, ENGLAND]
+    housing_benefit_family_premium_category: [NONE, ORDINARY_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, ORDINARY_PROTECTED]
+    is_child_or_young_person_for_legacy_benefits: [true, true, true, true, false]
+    is_lone_parent: [false, true, true, false, true]
+    housing_benefit_pension_age_regulations_apply: [false, false, false, false, false]
+    housing_benefit_eligible: [true, true, true, true, true]
+    eldest_claimant_or_partner_age: [40, 40, 40, 40, 40]
+    is_single_person: [true, false, false, true, false]
+    is_couple: [false, false, false, false, false]
+    benefits_premiums: [100, 100, 100, 100, 100]
+  output:
+    housing_benefit_family_premium: [0, 1051.44, 1154.3999999999999, 1051.44, 0]
+    housing_benefit_applicable_amount: [5068.599999999999, 6120.04, 6223, 6120.04, 5068.599999999999]
+
+# Cases: none; ordinary; historical lone parent; no longer lone parent; no child.
+- name: ENGLAND pension regime true protected family categories
+  period: 2026
+  absolute_error_margin: 0.02
+  input:
+    country: [ENGLAND, ENGLAND, ENGLAND, ENGLAND, ENGLAND]
+    housing_benefit_family_premium_category: [NONE, ORDINARY_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, ORDINARY_PROTECTED]
+    is_child_or_young_person_for_legacy_benefits: [true, true, true, true, false]
+    is_lone_parent: [false, true, true, false, true]
+    housing_benefit_pension_age_regulations_apply: [true, true, true, true, true]
+    # The claimants attained State Pension age before 1 April 2021, so the
+    # higher pension-age personal allowances apply (SI 2021/188).
+    housing_benefit_attained_pension_age_before_cutoff: [true, true, true, true, true]
+    housing_benefit_eligible: [true, true, true, true, true]
+    eldest_claimant_or_partner_age: [75, 75, 75, 75, 75]
+    is_single_person: [true, false, false, true, false]
+    is_couple: [false, false, false, false, false]
+    benefits_premiums: [100, 100, 100, 100, 100]
+  output:
+    housing_benefit_family_premium: [0, 1051.44, 1051.44, 1051.44, 0]
+    housing_benefit_applicable_amount: [13412, 14463.440000000002, 14463.440000000002, 14463.440000000002, 13412]
+
+# Cases: none; ordinary; historical lone parent; no longer lone parent; no child.
+- name: NORTHERN_IRELAND pension regime false protected family categories
+  period: 2026
+  absolute_error_margin: 0.02
+  input:
+    country: [NORTHERN_IRELAND, NORTHERN_IRELAND, NORTHERN_IRELAND, NORTHERN_IRELAND, NORTHERN_IRELAND]
+    housing_benefit_family_premium_category: [NONE, ORDINARY_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, ORDINARY_PROTECTED]
+    is_child_or_young_person_for_legacy_benefits: [true, true, true, true, false]
+    is_lone_parent: [false, true, true, false, true]
+    housing_benefit_pension_age_regulations_apply: [false, false, false, false, false]
+    housing_benefit_eligible: [true, true, true, true, true]
+    eldest_claimant_or_partner_age: [40, 40, 40, 40, 40]
+    is_single_person: [true, false, false, true, false]
+    is_couple: [false, false, false, false, false]
+    benefits_premiums: [100, 100, 100, 100, 100]
+  output:
+    housing_benefit_family_premium: [0, 1051.44, 1154.3999999999999, 1051.44, 0]
+    housing_benefit_applicable_amount: [5068.599999999999, 6120.04, 6223, 6120.04, 5068.599999999999]
+
+# Cases: none; ordinary; historical lone parent; no longer lone parent; no child.
+- name: NORTHERN_IRELAND pension regime true protected family categories
+  period: 2026
+  absolute_error_margin: 0.02
+  input:
+    country: [NORTHERN_IRELAND, NORTHERN_IRELAND, NORTHERN_IRELAND, NORTHERN_IRELAND, NORTHERN_IRELAND]
+    housing_benefit_family_premium_category: [NONE, ORDINARY_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, HISTORICAL_LONE_PARENT_PROTECTED, ORDINARY_PROTECTED]
+    is_child_or_young_person_for_legacy_benefits: [true, true, true, true, false]
+    is_lone_parent: [false, true, true, false, true]
+    housing_benefit_pension_age_regulations_apply: [true, true, true, true, true]
+    # The claimants attained State Pension age before 1 April 2021, so the
+    # higher pension-age personal allowances apply (SR 2021/70).
+    housing_benefit_attained_pension_age_before_cutoff: [true, true, true, true, true]
+    housing_benefit_eligible: [true, true, true, true, true]
+    eldest_claimant_or_partner_age: [75, 75, 75, 75, 75]
+    is_single_person: [true, false, false, true, false]
+    is_couple: [false, false, false, false, false]
+    benefits_premiums: [100, 100, 100, 100, 100]
+  output:
+    housing_benefit_family_premium: [0, 1051.44, 1051.44, 1051.44, 0]
+    housing_benefit_applicable_amount: [13412, 14463.440000000002, 14463.440000000002, 14463.440000000002, 13412]
+
+- name: Ordinary family premium published history 2015
+  period: 2015
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 17.45 * 52
+
+- name: Ordinary family premium published history 2020
+  period: 2020
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 17.6 * 52
+
+- name: Ordinary family premium published history 2021
+  period: 2021
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 17.65 * 52
+
+- name: Ordinary family premium published history 2022
+  period: 2022
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 17.85 * 52
+
+- name: Ordinary family premium published history 2023
+  period: 2023
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 18.53 * 52
+
+- name: Ordinary family premium published history 2024
+  period: 2024
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 19.15 * 52
+
+- name: Ordinary family premium published history 2025
+  period: 2025
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 19.48 * 52
+
+- name: Ordinary family premium published history 2026
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: false
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 20.22 * 52
+
+- name: Before closure ordinary family premium needs no historical category
+  period: 2015
+  absolute_error_margin: 0.01
+  input:
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: true
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium_category: NONE
+    housing_benefit_family_premium: 17.45 * 52
+
+- name: Missing category in closure year does not presume a protected claim
+  period: 2016
+  input:
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: true
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium_category: NONE
+    housing_benefit_family_premium: 0
+
+- name: Parameter reform overrides the protected ordinary amount
+  period: 2026
+  input:
+    gov.dwp.housing_benefit.premiums.family.amount: 0
+    housing_benefit_family_premium_category: ORDINARY_PROTECTED
+    is_child_or_young_person_for_legacy_benefits: true
+    is_lone_parent: true
+    housing_benefit_pension_age_regulations_apply: false
+  output:
+    housing_benefit_family_premium: 0
+
+- name: Child or young person status excludes an unrelated adult and a looked after child
+  period: 2026
+  input:
+    people:
+      parent:
+        age: 40
+        is_claimant_or_partner: true
+      looked_after:
+        age: 10
+        is_looked_after_by_local_authority: true
+      unrelated_adult:
+        age: 30
+    benunits:
+      family:
+        members: [parent, looked_after, unrelated_adult]
+        housing_benefit_family_premium_category: ORDINARY_PROTECTED
+  output:
+    housing_benefit_family_premium: 0

policyengine_uk/variables/gov/dwp/housing_benefit/housing_benefit_applicable_amount.py

@@ -18,6 +18,8 @@ class housing_benefit_applicable_amount(Variable):
         "https://www.legislation.gov.uk/nisr/2006/405/schedule/4/part/I",
         "https://www.legislation.gov.uk/nisr/2006/405/schedule/4",
         "https://www.legislation.gov.uk/nisr/2006/406/schedule/4",
+        "https://www.legislation.gov.uk/uksi/2015/1857/made",
+        "https://www.legislation.gov.uk/nisr/2016/310/made",
     )
 
     def formula(benunit, period, parameters):
@@ -93,8 +95,15 @@ def higher_allowance(category):
             + lone_parent * lone_parent_personal_allowance
         ) * WEEKS_IN_YEAR
         premiums = benunit("benefits_premiums", period)
+        family_premium = benunit("housing_benefit_family_premium", period)
         child_premiums = benunit("housing_benefit_child_disability_premiums", period)
         esa_adjustment = benunit(
             "housing_benefit_main_phase_esa_allowance_adjustment", period
         )
-        return personal_allowance + premiums + child_premiums + esa_adjustment
+        return (
+            personal_allowance
+            + premiums
+            + family_premium
+            + child_premiums
+            + esa_adjustment
+        )