Add Kingston upon Thames council tax reduction (#1771)

MaxGhenis · web-flow · commit d1cbf9b647c7 · 2026-06-07T03:14:51.000+02:00
diff --git a/changelog.d/council-tax-reduction-kingston-upon-thames.md b/changelog.d/council-tax-reduction-kingston-upon-thames.md
@@ -0,0 +1 @@
+- Add working-age Council Tax Reduction for Kingston upon Thames.
diff --git a/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/maximum_support_rate.yaml b/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/maximum_support_rate.yaml
@@ -0,0 +1,10 @@
+description: Maximum share of eligible Council Tax liability covered for working-age households under the Kingston upon Thames Council Tax Reduction scheme.
+values:
+  2026-04-01: 1
+metadata:
+  unit: /1
+  period: year
+  label: Kingston upon Thames Council Tax Reduction maximum support rate
+  reference:
+    - title: Council Tax Reduction Scheme 2026 - 2027
+      href: https://www.kingston.gov.uk/sites/default/files/2026-03/Council%20Tax%20Reduction%20Scheme%202026%20-%202027.pdf
diff --git a/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/capital_limit.yaml b/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/capital_limit.yaml
@@ -0,0 +1,10 @@
+description: Capital limit for working-age households under the Kingston upon Thames Council Tax Reduction scheme.
+values:
+  2026-04-01: 16_000
+metadata:
+  unit: currency-GBP
+  period: year
+  label: Kingston upon Thames Council Tax Reduction capital limit
+  reference:
+    - title: Council Tax Reduction Scheme 2026 - 2027
+      href: https://www.kingston.gov.uk/sites/default/files/2026-03/Council%20Tax%20Reduction%20Scheme%202026%20-%202027.pdf
diff --git a/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/tariff_income_step.yaml b/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/tariff_income_step.yaml
@@ -0,0 +1,10 @@
+description: Capital step above which one pound of weekly tariff income is added for working-age non-Universal Credit claimants under the Kingston upon Thames Council Tax Reduction scheme.
+values:
+  2026-04-01: 250
+metadata:
+  unit: currency-GBP
+  period: week
+  label: Kingston upon Thames Council Tax Reduction tariff income step
+  reference:
+    - title: Council Tax Reduction Scheme 2026 - 2027
+      href: https://www.kingston.gov.uk/sites/default/files/2026-03/Council%20Tax%20Reduction%20Scheme%202026%20-%202027.pdf
diff --git a/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/tariff_income_threshold.yaml b/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/tariff_income_threshold.yaml
@@ -0,0 +1,10 @@
+description: Capital threshold above which tariff income is added for working-age non-Universal Credit claimants under the Kingston upon Thames Council Tax Reduction scheme.
+values:
+  2026-04-01: 6_000
+metadata:
+  unit: currency-GBP
+  period: year
+  label: Kingston upon Thames Council Tax Reduction tariff income threshold
+  reference:
+    - title: Council Tax Reduction Scheme 2026 - 2027
+      href: https://www.kingston.gov.uk/sites/default/files/2026-03/Council%20Tax%20Reduction%20Scheme%202026%20-%202027.pdf
diff --git a/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/withdrawal_rate.yaml b/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/means_test/withdrawal_rate.yaml
@@ -0,0 +1,10 @@
+description: Withdrawal rate for working-age households under the Kingston upon Thames Council Tax Reduction scheme.
+values:
+  2026-04-01: 0.2
+metadata:
+  unit: /1
+  period: year
+  label: Kingston upon Thames Council Tax Reduction withdrawal rate
+  reference:
+    - title: Council Tax Reduction Scheme 2026 - 2027
+      href: https://www.kingston.gov.uk/sites/default/files/2026-03/Council%20Tax%20Reduction%20Scheme%202026%20-%202027.pdf
diff --git a/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/non_dep_deduction/amount.yaml b/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/non_dep_deduction/amount.yaml
@@ -0,0 +1,27 @@
+description: Weekly working-age non-dependant deduction schedule under the Kingston upon Thames Council Tax Reduction scheme.
+brackets:
+  - threshold:
+      2026-04-01: 0
+    amount:
+      2026-04-01: 5.64
+  - threshold:
+      2026-04-01: 279
+    amount:
+      2026-04-01: 11.50
+  - threshold:
+      2026-04-01: 485
+    amount:
+      2026-04-01: 14.43
+  - threshold:
+      2026-04-01: 605
+    amount:
+      2026-04-01: 17.31
+metadata:
+  amount_unit: currency-GBP
+  period: week
+  threshold_unit: currency-GBP
+  type: single_amount
+  label: Kingston upon Thames Council Tax Reduction non-dependant deduction schedule
+  reference:
+    - title: Council Tax Reduction Scheme 2026 - 2027
+      href: https://www.kingston.gov.uk/sites/default/files/2026-03/Council%20Tax%20Reduction%20Scheme%202026%20-%202027.pdf
diff --git a/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/non_dep_deduction/remunerative_work_hours.yaml b/policyengine_uk/parameters/gov/local_authorities/kingston_upon_thames/council_tax_reduction/non_dep_deduction/remunerative_work_hours.yaml
@@ -0,0 +1,10 @@
+description: Weekly hours threshold for remunerative work in the Kingston upon Thames Council Tax Reduction non-dependant deduction schedule.
+values:
+  2026-04-01: 16
+metadata:
+  unit: hour
+  period: week
+  label: Kingston upon Thames Council Tax Reduction remunerative work hours
+  reference:
+    - title: Council Tax Reduction Scheme 2026 - 2027
+      href: https://www.kingston.gov.uk/sites/default/files/2026-03/Council%20Tax%20Reduction%20Scheme%202026%20-%202027.pdf
diff --git a/policyengine_uk/tests/policy/baseline/gov/local_authorities/council_tax_reduction/council_tax_reduction.yaml b/policyengine_uk/tests/policy/baseline/gov/local_authorities/council_tax_reduction/council_tax_reduction.yaml
@@ -251,3 +251,159 @@
   output:
     uc_assessable_capital: 0
     council_tax_reduction: 1_800
+
+- name: Kingston upon Thames working-age claimant can receive full support
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 35
+    benunits:
+      benunit:
+        members: [claimant]
+        would_claim_uc: false
+        claims_all_entitled_benefits: true
+    households:
+      household:
+        members: [claimant]
+        country: ENGLAND
+        local_authority: KINGSTON_UPON_THAMES
+        council_tax: 1_800
+        savings: 0
+  output:
+    council_tax_reduction_scheme_supported: true
+    simulated_council_tax_reduction_benunit: 1_800
+    council_tax_reduction: 1_800
+    council_tax_less_benefit: 0
+
+- name: Kingston upon Thames working-age claimant above capital limit gets no local support
+  period: 2026
+  absolute_error_margin: 0
+  input:
+    people:
+      claimant:
+        age: 35
+        council_tax_benefit_reported: 500
+    benunits:
+      benunit:
+        members: [claimant]
+        claims_all_entitled_benefits: true
+    households:
+      household:
+        members: [claimant]
+        country: ENGLAND
+        local_authority: KINGSTON_UPON_THAMES
+        council_tax: 1_800
+        savings: 16_001
+  output:
+    council_tax_reduction_scheme_supported: true
+    simulated_council_tax_reduction_benunit: 0
+    council_tax_benefit: 0
+    council_tax_reduction: 0
+
+- name: Kingston upon Thames adds one weekly pound of tariff income for any partial 250 pounds above 6,000
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 35
+    benunits:
+      benunit:
+        members: [claimant]
+        would_claim_uc: false
+        claims_all_entitled_benefits: true
+        council_tax_reduction_applicable_amount: 0
+        council_tax_reduction_applicable_income: 0
+    households:
+      household:
+        members: [claimant]
+        country: ENGLAND
+        local_authority: KINGSTON_UPON_THAMES
+        council_tax: 1_800
+        savings: 6_001
+  output:
+    kingston_upon_thames_council_tax_reduction: 1_789.60
+    council_tax_reduction: 1_789.60
+    council_tax_less_benefit: 10.40
+
+- name: Kingston upon Thames applies its 2026 local non-dependant deduction schedule
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 35
+      non_dep:
+        age: 25
+        employment_income: 15_000
+        weekly_hours: 16
+    benunits:
+      claimant_benunit:
+        members: [claimant]
+        would_claim_uc: false
+        claims_all_entitled_benefits: true
+      non_dep_benunit:
+        members: [non_dep]
+    households:
+      household:
+        members: [claimant, non_dep]
+        country: ENGLAND
+        local_authority: KINGSTON_UPON_THAMES
+        council_tax: 1_800
+        savings: 0
+  output:
+    council_tax_reduction_scheme_supported: true
+    council_tax_reduction: 1_202
+
+- name: Kingston upon Thames UC claimant uses UC maximum amount and DWP income
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 35
+    benunits:
+      claimant_benunit:
+        members: [claimant]
+        would_claim_uc: true
+        claims_all_entitled_benefits: true
+        uc_maximum_amount: 5_000
+        uc_income_reduction: 2_500
+        uc_earned_income: 6_000
+        uc_unearned_income: 0
+    households:
+      household:
+        members: [claimant]
+        country: ENGLAND
+        local_authority: KINGSTON_UPON_THAMES
+        council_tax: 1_800
+        savings: 0
+  output:
+    universal_credit: 2_500
+    council_tax_reduction: 1_100
+
+- name: Kingston upon Thames UC claimant uses UC-reported capital
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 35
+    benunits:
+      claimant_benunit:
+        members: [claimant]
+        would_claim_uc: true
+        claims_all_entitled_benefits: true
+        uc_reported_capital: 0
+    households:
+      household:
+        members: [claimant]
+        country: ENGLAND
+        local_authority: KINGSTON_UPON_THAMES
+        council_tax: 1_800
+        savings: 20_000
+  output:
+    uc_assessable_capital: 0
+    council_tax_reduction: 1_800
diff --git a/policyengine_uk/variables/gov/local_authorities/council_tax_reduction/_legacy.py b/policyengine_uk/variables/gov/local_authorities/council_tax_reduction/_legacy.py
@@ -16,6 +16,7 @@ def legacy_council_tax_reduction(
     ctr,
     working_age,
     non_dep_deductions_variable,
+    additional_applicable_income=0,
 ):
     is_household_head_benunit = benunit("benunit_contains_household_head", period)
     would_claim = benunit("would_claim_council_tax_reduction", period)
@@ -31,6 +32,7 @@ def legacy_council_tax_reduction(
     )
     applicable_amount = where(has_uc_award, uc_applicable_amount, applicable_amount)
     applicable_income = where(has_uc_award, uc_applicable_income, applicable_income)
+    applicable_income += additional_applicable_income
     relevant_income_based_benefit = benunit(
         "council_tax_reduction_relevant_income_based_benefit",
         period,
diff --git a/policyengine_uk/variables/gov/local_authorities/council_tax_reduction/config.py b/policyengine_uk/variables/gov/local_authorities/council_tax_reduction/config.py
@@ -23,10 +23,23 @@ def is_merton_working_age(local_authority, country, has_pensioner):
     return (country == Country.ENGLAND) & ~has_pensioner & is_merton(local_authority)
 
 
+def is_kingston_upon_thames(local_authority):
+    return local_authority == LocalAuthority.KINGSTON_UPON_THAMES
+
+
+def is_kingston_upon_thames_working_age(local_authority, country, has_pensioner):
+    return (
+        (country == Country.ENGLAND)
+        & ~has_pensioner
+        & is_kingston_upon_thames(local_authority)
+    )
+
+
 def is_supported_scheme(country, has_pensioner, local_authority):
     return (
         is_england_pensioner_scheme(country, has_pensioner)
         | is_scotland_scheme(country)
         | is_wales_scheme(country)
         | is_merton_working_age(local_authority, country, has_pensioner)
+        | is_kingston_upon_thames_working_age(local_authority, country, has_pensioner)
     )
diff --git a/policyengine_uk/variables/gov/local_authorities/council_tax_reduction/simulated_council_tax_reduction_benunit.py b/policyengine_uk/variables/gov/local_authorities/council_tax_reduction/simulated_council_tax_reduction_benunit.py
@@ -5,7 +5,10 @@
     is_wales_scheme,
 )
 
-LOCAL_COUNCIL_TAX_REDUCTION_VARIABLES = ["merton_council_tax_reduction"]
+LOCAL_COUNCIL_TAX_REDUCTION_VARIABLES = [
+    "merton_council_tax_reduction",
+    "kingston_upon_thames_council_tax_reduction",
+]
 
 
 class simulated_council_tax_reduction_benunit(Variable):
diff --git a/policyengine_uk/variables/gov/local_authorities/kingston_upon_thames/council_tax_reduction/kingston_upon_thames_council_tax_reduction.py b/policyengine_uk/variables/gov/local_authorities/kingston_upon_thames/council_tax_reduction/kingston_upon_thames_council_tax_reduction.py
@@ -0,0 +1,45 @@
+from policyengine_uk.model_api import *
+import numpy as np
+from policyengine_uk.variables.gov.local_authorities.council_tax_reduction._legacy import (
+    legacy_council_tax_reduction,
+)
+from policyengine_uk.variables.gov.local_authorities.council_tax_reduction.config import (
+    is_kingston_upon_thames_working_age,
+)
+
+
+class kingston_upon_thames_council_tax_reduction(Variable):
+    value_type = float
+    entity = BenUnit
+    label = "Kingston upon Thames Council Tax Reduction"
+    definition_period = YEAR
+    unit = GBP
+
+    def formula(benunit, period, parameters):
+        ctr = parameters(
+            period
+        ).gov.local_authorities.kingston_upon_thames.council_tax_reduction
+        household = benunit.household
+        working_age = is_kingston_upon_thames_working_age(
+            household("local_authority", period),
+            household("country", period),
+            household("council_tax_reduction_household_has_pensioner", period),
+        )
+        has_uc_award = benunit("universal_credit", period) > 0
+        capital = household("savings", period)
+        weekly_tariff_income = np.ceil(
+            max_(0, capital - ctr.means_test.tariff_income_threshold)
+            / ctr.means_test.tariff_income_step
+        )
+        return legacy_council_tax_reduction(
+            benunit,
+            period,
+            ctr,
+            working_age,
+            "kingston_upon_thames_council_tax_reduction_non_dep_deductions",
+            additional_applicable_income=where(
+                has_uc_award,
+                0,
+                weekly_tariff_income * WEEKS_IN_YEAR,
+            ),
+        )
diff --git a/policyengine_uk/variables/gov/local_authorities/kingston_upon_thames/council_tax_reduction/kingston_upon_thames_council_tax_reduction_individual_non_dep_deduction.py b/policyengine_uk/variables/gov/local_authorities/kingston_upon_thames/council_tax_reduction/kingston_upon_thames_council_tax_reduction_individual_non_dep_deduction.py
@@ -0,0 +1,34 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.variables.gov.local_authorities.council_tax_reduction._legacy import (
+    normal_gross_income_non_dep_deduction,
+)
+from policyengine_uk.variables.gov.local_authorities.council_tax_reduction.config import (
+    is_kingston_upon_thames_working_age,
+)
+
+
+class kingston_upon_thames_council_tax_reduction_individual_non_dep_deduction(Variable):
+    value_type = float
+    entity = Person
+    label = "Kingston upon Thames CTR individual non-dependent deduction"
+    definition_period = YEAR
+    unit = GBP
+    defined_for = "council_tax_reduction_individual_non_dep_deduction_eligible"
+
+    def formula(person, period, parameters):
+        ctr = parameters(
+            period
+        ).gov.local_authorities.kingston_upon_thames.council_tax_reduction
+        household = person.household
+        working_age = is_kingston_upon_thames_working_age(
+            household("local_authority", period),
+            household("country", period),
+            household("council_tax_reduction_household_has_pensioner", period),
+        )
+        return normal_gross_income_non_dep_deduction(
+            person,
+            period,
+            ctr,
+            working_age,
+            exempt_uc_no_earned_income=True,
+        )
diff --git a/policyengine_uk/variables/gov/local_authorities/kingston_upon_thames/council_tax_reduction/kingston_upon_thames_council_tax_reduction_non_dep_deductions.py b/policyengine_uk/variables/gov/local_authorities/kingston_upon_thames/council_tax_reduction/kingston_upon_thames_council_tax_reduction_non_dep_deductions.py

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+- Add working-age Council Tax Reduction for Kingston upon Thames.`