Add uk-council-tax-reduction comparison; cover CTR on uk-pe (13/25 → 14/25)

comparisons/affected_map.json

@@ -352,6 +352,14 @@
       ],
       "source": "comparisons/uk-child-benefit-ukmod.yaml"
     },
+    {
+      "suite": "uk-council-tax-reduction",
+      "report": "axiom-policyengine-uk-council-tax-reduction.json",
+      "repos": [
+        "TheAxiomFoundation/rulespec-uk"
+      ],
+      "source": "comparisons/uk-council-tax-reduction.yaml"
+    },
     {
       "suite": "uk-employer-nic",
       "report": "axiom-euromod-uk-employer-nic.json",

comparisons/uk-council-tax-reduction.yaml

@@ -0,0 +1,45 @@
+# Council Tax Reduction — rulespec-uk England pension-age scheme vs PolicyEngine-UK
+# on a synthetic pensioner-household grid. The Axiom side is the encoded England
+# pension-age prescribed scheme (SI 2012/2885 Schedule 1),
+# uk/policies/govuk/council-tax-reduction.yaml, evaluated through the axiom rules
+# engine over PolicyEngine's own applicable amount / applicable income /
+# non-dependant deductions / council_tax liability / savings (the uk-pension-credit
+# bridge pattern). PolicyEngine gained a council_tax_reduction formula in 2.89.2
+# (PolicyEngine/policyengine-uk#1769 national core + #1771 Kingston, both merged).
+#
+# council_tax liability is a supplied input on both sides, so the schemes are
+# commensurable and the grid matches to the penny (full award below the
+# applicable amount, the 20 per cent taper interior, the 16000 capital screen,
+# single and couple applicable amounts); the only residuals are sub-0.001
+# PolicyEngine float32 artifacts, inside tolerance.
+#
+# Run locally (needs a PolicyEngine-UK 2.89.2 env, a built axiom rules engine and
+# the rulespec-uk checkout):
+#   uv run python scripts/run_comparison.py uk-council-tax-reduction
+
+name: uk-council-tax-reduction
+title: UK Council Tax Reduction — Axiom vs PolicyEngine
+description: >-
+  Compares the encoded England pension-age Council Tax Reduction scheme
+  (rulespec-uk uk/policies/govuk/council-tax-reduction.yaml, SI 2012/2885) against
+  PolicyEngine-UK council_tax_reduction (2.89.2) at the 2026 validation year on a
+  synthetic pensioner-household grid crossing the 20 per cent taper and the 16000
+  capital limit. council_tax liability is a supplied input on both engines.
+documentation: docs/uk-coverage-matrix.md
+
+runner:
+  type: uk-council-tax-reduction-grid
+  parameters:
+    period: "2026"
+    policyengine_uk_version: "2.89.2"
+    # Links this suite to the rulespec-uk monorepo in the affected map so a
+    # change to the encoded England pension-age scheme triggers a re-run.
+    rulespec_roots:
+      - $HOME/TheAxiomFoundation/rulespec-uk
+
+artifacts:
+  report_basename: axiom-policyengine-uk-council-tax-reduction
+
+dashboard:
+  filename: axiom-policyengine-uk-council-tax-reduction.json
+  suite: uk-council-tax-reduction

conformance/detail/uk-pe.json

@@ -152,18 +152,18 @@
       "oracle_policy_name": "council_tax_reduction",
       "in_scope": true,
       "exclusion_reason": null,
-      "suite": null,
-      "covered": false,
-      "comparisons": null,
-      "matches": null,
-      "raw_match_rate": null,
+      "suite": "uk-council-tax-reduction",
+      "covered": true,
+      "comparisons": 11,
+      "matches": 11,
+      "raw_match_rate": 100.0,
       "explained_rate": null,
-      "unexplained": null,
-      "axiom_attributed_open": null,
-      "oracle_attributed": null,
-      "bridge_artifacts": null,
-      "note": "In-scope uncovered \u2014 council_tax_reduction now HAS a formula in PE-UK 2.89.2 (the matrix ambiguity at HEAD 45eb181c, where the variable was absent, is resolved on this pin); rulespec encodes England pension-age + council schemes but no CTR suite runs yet (matrix row 29 \u2192 LGFA 1992 s.13A + Sch.1A).",
-      "status": "uncovered"
+      "unexplained": 0,
+      "axiom_attributed_open": 0,
+      "oracle_attributed": 0,
+      "bridge_artifacts": 0,
+      "note": "Covered by the uk-council-tax-reduction case-grid suite. council_tax_reduction gained a formula in PE-UK 2.89.2 (#1769 national core + #1771 Kingston, both merged), resolving the matrix ambiguity at HEAD 45eb181c where the variable was absent. The suite compares PE-UK's England pension-age path (gov.local_authorities.england.council_tax_reduction.pensioners: max-support 1, capital limit 16000, withdrawal 0.20) against the rulespec SI 2012/2885 England pension-age scheme (uk/policies/govuk/council-tax-reduction.yaml) on a synthetic pensioner grid, bridging PE's own applicable amount / applicable income / non-dependant deductions / council_tax liability / savings into the rulespec supplied inputs (the uk-pension-credit bridge pattern). council_tax is a supplied input on both sides, so the schemes are commensurable; all 11 cases match to the penny (the taper interior, the capital screen, single and couple), residuals sub-0.001 (PE float32), inside tolerance. The England pension-age income test does not inherit the #1794 Housing Benefit earnings-disregard defect \u2014 council_tax_reduction_applicable_income applies no earnings disregard. matrix row 29 \u2192 LGFA 1992 s.13A + Sch.1A; SI 2012/2885.",
+      "status": "conformant"
     },
     {
       "id": "uk-pe:dla",

conformance/ratchet.yaml

@@ -15,7 +15,7 @@ ratchets:
   axiom_attributed_open_max: 0
   policies_in_scope: 27
 - jurisdiction: uk-pe
-  covered_min: 13
+  covered_min: 14
   unexplained_max: 0
   axiom_attributed_open_max: 0
   policies_in_scope: 25

conformance/scoreboard.json

@@ -72,8 +72,8 @@
       "jurisdiction": "uk-pe",
       "oracle": "policyengine-uk_2.89.2/uk",
       "policies_in_scope": 25,
-      "covered": 13,
-      "covered_pct": 52.0,
+      "covered": 14,
+      "covered_pct": 56.0,
       "excluded": 8,
       "excluded_by_reason": {
         "input_carrying": 8
@@ -87,7 +87,6 @@
         "attendance_allowance",
         "business_rates",
         "capital_gains_tax",
-        "council_tax_reduction",
         "fuel_duty",
         "lbtt_ltt",
         "legacy_means_tested",
@@ -98,7 +97,7 @@
         "winter_fuel_allowance"
       ],
       "blocking_reasons": [
-        "12 of 25 in-scope policies are not covered by a live suite: attendance_allowance, business_rates, capital_gains_tax, council_tax_reduction, fuel_duty, lbtt_ltt, legacy_means_tested, state_pension, tax_free_childcare, tv_licence, vat, winter_fuel_allowance"
+        "11 of 25 in-scope policies are not covered by a live suite: attendance_allowance, business_rates, capital_gains_tax, fuel_duty, lbtt_ltt, legacy_means_tested, state_pension, tax_free_childcare, tv_licence, vat, winter_fuel_allowance"
       ]
     }
   ]

conformance/uk-pe.yaml

@@ -103,10 +103,20 @@ policies:
     output_vars:
       - council_tax_reduction
     in_scope: true
-    suite: null
-    note: In-scope uncovered — council_tax_reduction now HAS a formula in PE-UK 2.89.2 (the matrix ambiguity
-      at HEAD 45eb181c, where the variable was absent, is resolved on this pin); rulespec encodes England
-      pension-age + council schemes but no CTR suite runs yet (matrix row 29 → LGFA 1992 s.13A + Sch.1A).
+    suite: uk-council-tax-reduction
+    note: 'Covered by the uk-council-tax-reduction case-grid suite. council_tax_reduction gained a formula
+      in PE-UK 2.89.2 (#1769 national core + #1771 Kingston, both merged), resolving the matrix ambiguity
+      at HEAD 45eb181c where the variable was absent. The suite compares PE-UK''s England pension-age path
+      (gov.local_authorities.england.council_tax_reduction.pensioners: max-support 1, capital limit 16000,
+      withdrawal 0.20) against the rulespec SI 2012/2885 England pension-age scheme
+      (uk/policies/govuk/council-tax-reduction.yaml) on a synthetic pensioner grid, bridging PE''s own
+      applicable amount / applicable income / non-dependant deductions / council_tax liability / savings
+      into the rulespec supplied inputs (the uk-pension-credit bridge pattern). council_tax is a supplied
+      input on both sides, so the schemes are commensurable; all 11 cases match to the penny (the taper
+      interior, the capital screen, single and couple), residuals sub-0.001 (PE float32), inside tolerance.
+      The England pension-age income test does not inherit the #1794 Housing Benefit earnings-disregard
+      defect — council_tax_reduction_applicable_income applies no earnings disregard. matrix row 29 → LGFA
+      1992 s.13A + Sch.1A; SI 2012/2885.'
   - id: uk-pe:dla
     oracle_policy_name: dla
     oracle_policy_type: rate_from_category

dashboard/public/data/axiom-policyengine-uk-council-tax-reduction.json

@@ -0,0 +1,228 @@
+{
+  "schema_version": "axiom.comparison_report.v2",
+  "suite": "uk-council-tax-reduction",
+  "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+  "population": "case-grid",
+  "validation_year": 2026,
+  "locales": [
+    "UK"
+  ],
+  "scope": {
+    "type": "country",
+    "geoid": "UK"
+  },
+  "engines": {
+    "axiom": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+    "policyengine": "council_tax_reduction"
+  },
+  "tolerance": {
+    "absolute": 0.01,
+    "relative": 2e-07
+  },
+  "case_count": 11,
+  "summary": {
+    "comparison_count": 11,
+    "match_count": 11,
+    "mismatch_count": 0,
+    "axiom_vs_policyengine_match_rate": 100.0,
+    "policyengine_matches": 11,
+    "weighted": {
+      "comparison_weight": 11,
+      "match_weight": 11,
+      "mismatch_weight": 0,
+      "match_rate": 100.0
+    },
+    "mismatches_by_concept": [],
+    "mismatches_by_kind": [],
+    "mismatches_by_scenario": [],
+    "error_count": 0,
+    "errors_by_engine": []
+  },
+  "mismatches": [],
+  "errors": [],
+  "cases": [
+    {
+      "case_id": "ctr-pa-single-full-below-aa",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "full-award-income-below-applicable-amount",
+      "couple": false,
+      "council_tax_liability": 1800.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 4000.0,
+      "household_capital": 0.0,
+      "axiom": 1800.0,
+      "policyengine": 1800.0,
+      "axiom_vs_policyengine": {
+        "difference": 0.0,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-full-income-at-aa",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "full-award-income-near-applicable-amount",
+      "couple": false,
+      "council_tax_liability": 1800.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 12914.0,
+      "household_capital": 0.0,
+      "axiom": 1800.0,
+      "policyengine": 1800.0,
+      "axiom_vs_policyengine": {
+        "difference": 0.0,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-taper-interior-a",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "taper-interior",
+      "couple": false,
+      "council_tax_liability": 3000.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 17163.599609375,
+      "household_capital": 0.0,
+      "axiom": 2229.680078125,
+      "policyengine": 2229.68017578125,
+      "axiom_vs_policyengine": {
+        "difference": -9.765625009094947e-05,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-taper-interior-b",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "taper-interior",
+      "couple": false,
+      "council_tax_liability": 3000.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 22645.19921875,
+      "household_capital": 0.0,
+      "axiom": 1133.36015625,
+      "policyengine": 1133.360107421875,
+      "axiom_vs_policyengine": {
+        "difference": 4.8828125045474735e-05,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-taper-interior-c",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "taper-interior",
+      "couple": false,
+      "council_tax_liability": 2500.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 18514.0,
+      "household_capital": 0.0,
+      "axiom": 1459.6,
+      "policyengine": 1459.5999755859375,
+      "axiom_vs_policyengine": {
+        "difference": 2.441406240905053e-05,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-taper-to-zero",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "taper-exhausts-award",
+      "couple": false,
+      "council_tax_liability": 1800.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 28114.0,
+      "household_capital": 0.0,
+      "axiom": 0.0,
+      "policyengine": 0.0,
+      "axiom_vs_policyengine": {
+        "difference": 0.0,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-capital-at-limit",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "capital-at-limit-eligible",
+      "couple": false,
+      "council_tax_liability": 1800.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 4000.0,
+      "household_capital": 16000.0,
+      "axiom": 1800.0,
+      "policyengine": 1800.0,
+      "axiom_vs_policyengine": {
+        "difference": 0.0,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-capital-over-limit",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "capital-over-limit-excluded",
+      "couple": false,
+      "council_tax_liability": 1800.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 4000.0,
+      "household_capital": 20000.0,
+      "axiom": 0.0,
+      "policyengine": 0.0,
+      "axiom_vs_policyengine": {
+        "difference": 0.0,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-single-high-council-tax",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "full-award-high-liability",
+      "couple": false,
+      "council_tax_liability": 2600.0,
+      "applicable_amount": 13312.0,
+      "applicable_income": 8000.0,
+      "household_capital": 0.0,
+      "axiom": 2600.0,
+      "policyengine": 2600.0,
+      "axiom_vs_policyengine": {
+        "difference": 0.0,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-couple-full-below-aa",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "couple-full-award",
+      "couple": true,
+      "council_tax_liability": 2200.0,
+      "applicable_amount": 19934.19921875,
+      "applicable_income": 6000.0,
+      "household_capital": 0.0,
+      "axiom": 2200.0,
+      "policyengine": 2200.0,
+      "axiom_vs_policyengine": {
+        "difference": 0.0,
+        "match": true
+      }
+    },
+    {
+      "case_id": "ctr-pa-couple-taper-interior",
+      "concept": "uk:policies/govuk/council-tax-reduction#council_tax_reduction_annual_amount",
+      "scenario": "couple-taper-interior",
+      "couple": true,
+      "council_tax_liability": 2400.0,
+      "applicable_amount": 19934.19921875,
+      "applicable_income": 21966.0,
+      "household_capital": 0.0,
+      "axiom": 1993.63984375,
+      "policyengine": 1993.639892578125,
+      "axiom_vs_policyengine": {
+        "difference": -4.8828125045474735e-05,
+        "match": true
+      }
+    }
+  ],
+  "provenance": {
+    "generated": "2026-07-06",
+    "generator": "scripts/generate_uk_council_tax_reduction.py",
+    "axiom_engine": "axiom rules engine over rulespec-uk uk/policies/govuk/council-tax-reduction.yaml",
+    "policyengine_uk": "2.89.2",
+    "commensurability": "PolicyEngine-UK England pension-age Council Tax Reduction (gov.local_authorities.england.council_tax_reduction.pensioners: max-support 1, capital limit 16000, withdrawal 0.20) vs the SI 2012/2885 prescribed pension-age scheme; council_tax liability is a supplied input on both sides. PolicyEngine's computed applicable amount, applicable income and non-dependant deductions are bridged into the rulespec supplied inputs."
+  }
+}