feat: add Wales infrastructure and Green Manifesto scoring

LEGISLATIVE_REFERENCE.md

@@ -415,7 +415,22 @@ yet migrated (governed by `uc_migration.housing_benefit` rates).
 Source: SI 2006/213 reg.70 ([`uksi/2006/213/regulation/70`](https://www.legislation.gov.uk/uksi/2006/213/regulation/70))
 
 Maximum HB = 100% of eligible rent (subject to LHA caps for private renters). The model does
-not compute LHA caps; it uses reported rent directly.
+not compute LHA caps; it uses reported rent directly as eligible rent for all tenures.
+
+LHA cap is implemented in `src/variables/benefits.rs` via `lha_monthly_cap()`. When `params.lha`
+is present and enabled, eligible rent for private renters (TenureType::RentPrivately) is capped
+at the regional LHA rate for the household's bedroom entitlement, computed by
+`lha_bedroom_entitlement()` (implements UC Regs 2013 Sch.4 / HB Regs 2006 Sch.B1).
+
+The LHA rates are stored as region×category monthly amounts in `params.lha.rates_monthly`.
+Since the FRS suppresses BRMA identifiers for disclosure reasons, the model uses region-level
+30th percentile rates (derived from the VOA list of rents via policyengine-uk, uprated using the
+ONS Index of Private Housing Rental Prices). This understates within-region variation but
+captures the main regional gradient. The 2025/26 baseline uses rates frozen at the 2024/25
+reset level (April 2024 reset to 30th percentile, re-frozen April 2025).
+
+Reform scenarios can vary `params.lha.private_rent_index` (multiplicative uprating of all rates,
+e.g. 1.10 = 10% increase) without changing the underlying rate table.
 
 ### 7.2 Applicable Amount
 

changelog.d/added/lha-cap.md

@@ -0,0 +1 @@
+Implement Local Housing Allowance cap for private renters on HB and UC: bedroom entitlement logic (UC Regs 2013 Sch.4), region×category monthly rate table derived from VOA rent data uprated to 2024/25, and a `private_rent_index` scalar for modelling LHA unfreeze or rate changes.

changelog.d/added/wales-green-manifesto.md

@@ -0,0 +1 @@
+Add Wales-specific modelling infrastructure (devolved council tax Band D rates, LTT, `is_in_wales` flag, universal FSM by nation) and score the first two Wales Green Manifesto 2026 policies: council tax abolition in Wales (~£3.7bn/yr) and extending universal free school meals to secondary pupils.

parameters/2025_26.yaml

@@ -236,7 +236,11 @@ tobacco_duty:
 council_tax:
   # Local Government Finance Act 1992 s.1-5
   # DLUHC Council Tax levels statistics 2025/26: England average Band D = £2,280
+  # Wales 2025/26 average Band D: £1,955 (Stats Wales / DLUHC)
+  # Scotland 2025/26 average Band D: £1,528 (Scottish Government)
   average_band_d: 2280.0
+  wales_average_band_d: 1955.0
+  scotland_average_band_d: 1528.0
 
 capital_gains_tax:
   # Taxation of Chargeable Gains Act 1992; Finance Act 2024 s.7 (rate increases)
@@ -247,7 +251,8 @@ capital_gains_tax:
   realisation_rate: 0.50
 
 stamp_duty:
-  # Finance Act 2003 s.55, as amended; bands from 1 April 2025
+  # Finance Act 2003 s.55, as amended; bands from 1 April 2025 (England and NI only)
+  # Wales uses LTT (see land_transaction_tax below); Scotland uses LBTT (not yet separate)
   bands:
     - { rate: 0.0, threshold: 0 }
     - { rate: 0.02, threshold: 125001 }
@@ -256,13 +261,77 @@ stamp_duty:
     - { rate: 0.12, threshold: 1500001 }
   annual_purchase_probability: 0.043  # ~1/23 year average holding period
 
+land_transaction_tax:
+  # Land Transaction Tax and Anti-avoidance of Devolved Taxes (Wales) Act 2017 (ANAW 2017/1)
+  # Welsh Government rates from 10 October 2022 (still current 2025/26)
+  # Welsh Revenue Authority: https://www.wra.gov.wales/land-transaction-tax/
+  # Residential main rates (not higher rates surcharge):
+  #   0%  £0–£225,000
+  #   6%  £225,001–£400,000
+  #   7.5%  £400,001–£750,000
+  #   10%  £750,001–£1,500,000
+  #   12%  over £1,500,000
+  bands:
+    - { rate: 0.0,   threshold: 0 }
+    - { rate: 0.06,  threshold: 225001 }
+    - { rate: 0.075, threshold: 400001 }
+    - { rate: 0.10,  threshold: 750001 }
+    - { rate: 0.12,  threshold: 1500001 }
+  annual_purchase_probability: 0.043
+
+free_school_meals:
+  # Welsh Government: universal free school meals for primary pupils (reception–year 6)
+  # rolled out from January 2024. Source: https://www.gov.wales/universal-primary-free-school-meals
+  # Cost per meal: approx £3.00 (Welsh Government estimate); 190 school days per year.
+  primary_annual_value: 570.0    # £3.00 × 190 days
+  secondary_annual_value: 570.0  # same unit cost assumption
+  # Baseline: Wales primary already universal
+  wales_primary_universal: true
+  # Baseline: Wales secondary NOT universal (Green proposal to extend it)
+  wales_secondary_universal: false
+
 wealth_tax:
   # Hypothetical — no current UK legislation. Disabled by default.
   # Wealth Tax Commission (2020) proposed 1% above £10m.
   enabled: false
   threshold: 10000000.0
   rate: 0.01
 
+# OBR fiscal headroom (UK-wide — not devolved).
+# Source: OBR Spring Statement March 2026, Economic and Fiscal Outlook.
+# Headroom against the supplementary debt rule: PSND ex (ex. BoE) falling as a % of GDP
+# in the fifth year of the forecast (2029/30). At Spring Statement 2026: £9.9bn.
+# Each £1bn of net new borrowing reduces this headroom by approximately £1bn
+# (obr_headroom_sensitivity = 1.0 is the OBR's central assumption absent dynamic scoring).
+lha:
+  # Local Housing Allowance rates for 2025/26.
+  # LHA was re-frozen in April 2025 at the 2024/25 reset rates.
+  # 2024/25 rates: 30th percentile of private rents in each BRMA, reset from freeze.
+  # Source: VOA list of rents (2019–2020 data), uprated to April 2024 using ONS Index of
+  #   Private Housing Rental Prices (index: April 2020 = 109.0, April 2024 ≈ 125.0;
+  #   uprate factor = 1.1468). Aggregated to GOR (region) as FRS suppresses BRMA identifiers.
+  # Categories: [A=shared, B=1-bed, C=2-bed, D=3-bed, E=4+bed] — monthly amounts (£).
+  # Row order: NE, NW, Yorkshire, E.Midlands, W.Midlands, E.ofEngland, London,
+  #            S.East, S.West, Wales, Scotland, N.Ireland.
+  enabled: true
+  private_rent_index: 1.0  # 1.0 = frozen (no uprating). Reform: set >1.0 to unfreeze.
+  rates_monthly:
+    - [323.01,  428.86,  486.06,  566.12,  766.23]   # North East
+    - [332.95,  457.44,  566.12,  657.60,  860.11]   # North West
+    - [323.01,  451.72,  543.26,  600.41,  857.72]   # Yorkshire
+    - [372.71,  486.06,  600.41,  686.18,  914.92]   # East Midlands
+    - [390.10,  514.63,  629.03,  743.38,  972.12]   # West Midlands
+    - [360.23,  629.03,  771.95,  886.35, 1252.29]   # East of England
+    - [580.97, 1200.81, 1469.61, 1735.40, 2172.93]   # London
+    - [392.58,  737.66,  914.92, 1086.46, 1543.90]   # South East
+    - [390.10,  571.83,  737.66,  874.87, 1143.66]   # South West
+    - [299.41,  419.92,  514.63,  566.12,  686.18]   # Wales
+    - [323.01,  468.91,  543.26,  629.03,  886.35]   # Scotland
+    - [273.42,  361.97,  428.86,  514.63,  566.12]   # Northern Ireland
+
+obr_fiscal_headroom_bn: 9.9
+obr_headroom_sensitivity: 1.0
+
 labour_supply:
   # OBR labour supply elasticities (Slutsky decomposition).
   # Source: OBR (2023) "Costing a cut in National Insurance contributions:

reforms/wales_green_manifesto.yaml

@@ -0,0 +1,38 @@
+# Wales Green Party Manifesto 2026 — scoreable policies
+#
+# This reform covers the Tier 1 and Tier 2 policies from the Wales Green
+# Manifesto that can be modelled as parameter changes. Applies for 2025/26.
+#
+# Policies included:
+#   1. Abolish council tax (Wales) — replace with LVT (Tier 3, not yet modelled);
+#      the abolition side is scored here by zeroing the calculated Band D rate.
+#      Revenue loss is captured in the fiscal impact output.
+#   2. Extend free school meals to secondary pupils in Wales (universal,
+#      wales_secondary_universal: true). Baseline already has universal primary.
+#
+# Policies NOT yet included (require additional model components):
+#   - LHA unfreeze: LHA cap not yet modelled (uses reported rent directly)
+#   - LVT replacement: new tax base — Tier 3 structural reform
+#   - Bus fare subsidies: no transport cost variable yet
+#   - Childcare expansion: childcare offer not yet parameterised
+#   - Rent freeze: rent is exogenous input
+
+council_tax:
+  # Abolish council tax in Wales only. Sets wales_average_band_d to zero, which
+  # scales Welsh households' CT to £0 while leaving England/Scotland unchanged.
+  # The fiscal cost is the Welsh CT revenue only (~5% of UK total CT).
+  # Source: Wales Green Manifesto 2026 — "council tax is unfair... we will replace
+  # it with a land value tax that cuts the average bill"
+  average_band_d: 2280.0
+  wales_average_band_d: 0.0
+  scotland_average_band_d: 1528.0
+
+free_school_meals:
+  # Extend universal FSM entitlement to secondary pupils (ages 11–15) in Wales.
+  # Baseline: universal primary already active (wales_primary_universal: true).
+  # Source: Wales Green Manifesto 2026 — "extend universal free school meals to
+  # secondary schools, helping reduce inequality"
+  wales_primary_universal: true
+  wales_secondary_universal: true
+  primary_annual_value: 570.0
+  secondary_annual_value: 570.0

src/data/clean.rs

@@ -34,7 +34,7 @@ fn write_persons(dataset: &Dataset, output_dir: &Path) -> anyhow::Result<()> {
         "property_income", "maintenance_income",
         "miscellaneous_income", "other_income",
         // Employment
-        "is_in_scotland", "hours_worked_annual",
+        "is_in_scotland", "is_in_wales", "hours_worked_annual",
         // Disability rate-band flags
         "dla_care_low", "dla_care_mid", "dla_care_high",
         "dla_mob_low", "dla_mob_high",
@@ -86,6 +86,7 @@ fn write_persons(dataset: &Dataset, output_dir: &Path) -> anyhow::Result<()> {
             format!("{:.2}", p.miscellaneous_income),
             format!("{:.2}", p.other_income),
             p.is_in_scotland.to_string(),
+            p.is_in_wales.to_string(),
             format!("{:.1}", p.hours_worked),
             p.dla_care_low.to_string(),
             p.dla_care_mid.to_string(),
@@ -340,7 +341,7 @@ fn write_microdata_csv_persons<W: std::io::Write>(
         "property_income", "maintenance_income",
         "miscellaneous_income", "other_income",
         // Employment
-        "is_in_scotland", "hours_worked_annual",
+        "is_in_scotland", "is_in_wales", "hours_worked_annual",
         // Status
         "is_disabled", "is_carer",
         // Contributions
@@ -384,6 +385,7 @@ fn write_microdata_csv_persons<W: std::io::Write>(
             format!("{:.2}", p.miscellaneous_income),
             format!("{:.2}", p.other_income),
             p.is_in_scotland.to_string(),
+            p.is_in_wales.to_string(),
             format!("{:.1}", p.hours_worked),
             p.is_disabled.to_string(),
             p.is_carer.to_string(),
@@ -672,12 +674,15 @@ pub fn assemble_dataset(
             bu.would_claim_jsa = bu.person_ids.iter().any(|&pid| people.get(pid).map_or(false, |p| p.jsa_income > 0.0));
         }
     }
-    // Auto-derive is_in_scotland from household region
+    // Auto-derive is_in_scotland / is_in_wales from household region
     for p in &mut people {
         if let Some(hh) = households.get(p.household_id) {
             if hh.region.is_scotland() {
                 p.is_in_scotland = true;
             }
+            if hh.region.is_wales() {
+                p.is_in_wales = true;
+            }
         }
     }
     Dataset {
@@ -838,6 +843,7 @@ pub fn parse_persons_csv<R: std::io::Read>(reader: R) -> anyhow::Result<Vec<Pers
             miscellaneous_income: h.get_f64(&r, "miscellaneous_income"),
             other_income: h.get_f64(&r, "other_income"),
             is_in_scotland: h.get_bool(&r, "is_in_scotland"),
+            is_in_wales: h.get_bool(&r, "is_in_wales"),
             hours_worked: h.get_f64(&r, "hours_worked_annual"),
             dla_care_low: h.get_bool(&r, "dla_care_low"),
             dla_care_mid: h.get_bool(&r, "dla_care_mid"),

src/data/frs.rs

@@ -973,6 +973,7 @@ fn assemble_dataset(
             if let Some(&bu_idx) = bu_map.get(&bu_key) {
                 let pid = people.len();
                 let is_scotland = households[hh_idx].region.is_scotland();
+                let is_wales = households[hh_idx].region.is_wales();
 
                 people.push(Person {
                     id: pid,
@@ -994,6 +995,7 @@ fn assemble_dataset(
                     miscellaneous_income: pr.miscellaneous_income_weekly * WEEKS_IN_YEAR,
                     other_income: 0.0,
                     is_in_scotland: is_scotland,
+                    is_in_wales: is_wales,
                     hours_worked: pr.hours_worked_weekly * 52.0,
                     dla_care_low: pr.dla_care_low,
                     dla_care_mid: pr.dla_care_mid,

src/engine/entities.rs

@@ -35,6 +35,7 @@ pub struct Person {
 
     // Employment
     pub is_in_scotland: bool,
+    pub is_in_wales: bool,
     pub hours_worked: f64,             // annual hours
 
     // Disability/carer status — granular rate-band flags derived from FRS benefit amounts
@@ -124,6 +125,7 @@ impl Default for Person {
             miscellaneous_income: 0.0,
             other_income: 0.0,
             is_in_scotland: false,
+            is_in_wales: false,
             hours_worked: 0.0,
             dla_care_low: false,
             dla_care_mid: false,
@@ -507,6 +509,10 @@ impl Region {
         matches!(self, Region::Scotland)
     }
 
+    pub fn is_wales(&self) -> bool {
+        matches!(self, Region::Wales)
+    }
+
     pub fn from_frs_code(code: i32) -> Self {
         match code {
             1 => Region::NorthEast,
@@ -560,6 +566,26 @@ impl Region {
         }
     }
 
+    /// LHA region index for rate table lookup (0–11, matching rates_monthly row order).
+    /// Order: NE=0, NW=1, Yorks=2, EM=3, WM=4, EofE=5, London=6, SE=7, SW=8,
+    ///        Wales=9, Scotland=10, NI=11.
+    pub fn to_lha_region_idx(&self) -> usize {
+        match self {
+            Region::NorthEast => 0,
+            Region::NorthWest => 1,
+            Region::Yorkshire => 2,
+            Region::EastMidlands => 3,
+            Region::WestMidlands => 4,
+            Region::EastOfEngland => 5,
+            Region::London => 6,
+            Region::SouthEast => 7,
+            Region::SouthWest => 8,
+            Region::Wales => 9,
+            Region::Scotland => 10,
+            Region::NorthernIreland => 11,
+        }
+    }
+
     pub fn name(&self) -> &'static str {
         match self {
             Region::NorthEast => "North East",

src/engine/simulation.rs

@@ -45,6 +45,10 @@ pub struct BenUnitResult {
     pub total_benefits: f64,
     pub uc_max_amount: f64,
     pub uc_income_reduction: f64,
+    /// Calculated free school meals value. When `free_school_meals` params are present,
+    /// this reflects eligibility-based modelling (e.g. Wales universal extension).
+    /// Falls back to the FRS-reported amount if no params provided.
+    pub free_school_meals: f64,
 }
 
 /// Results for a household
@@ -262,11 +266,18 @@ impl Simulation {
                 .map(|&pid| self.people[pid].employee_pension_contributions + self.people[pid].personal_pension_contributions)
                 .sum();
 
-            // In-kind benefits included in HBAI net income
+            // In-kind benefits included in HBAI net income.
+            // When FSM params are present, use the calculated modelled amount rather
+            // than the raw FRS-reported figure so that reform scenarios apply correctly.
             let in_kind_benefits: f64 = hh.benunit_ids.iter()
                 .map(|&bid| {
                     let bu = &self.benunits[bid];
-                    bu.free_school_meals + bu.free_school_fruit_veg + bu.free_school_milk
+                    let fsm = if self.parameters.free_school_meals.is_some() {
+                        benunit_results[bid].free_school_meals
+                    } else {
+                        bu.free_school_meals
+                    };
+                    fsm + bu.free_school_fruit_veg + bu.free_school_milk
                         + bu.healthy_start_vouchers + bu.free_tv_licence
                 })
                 .sum();
@@ -299,10 +310,13 @@ impl Simulation {
                 .map(|&pid| person_results[pid].capital_gains_tax)
                 .sum();
 
-            // Stamp duty (annualised)
-            let stamp_duty = self.parameters.stamp_duty.as_ref()
-                .map(|p| variables::wealth_taxes::calculate_stamp_duty(hh, p))
-                .unwrap_or(0.0);
+            // Property transaction tax: LTT for Wales, SDLT for England/NI.
+            // Routes automatically based on household region.
+            let stamp_duty = variables::wealth_taxes::calculate_property_transaction_tax(
+                hh,
+                self.parameters.stamp_duty.as_ref(),
+                self.parameters.land_transaction_tax.as_ref(),
+            );
 
             // Wealth tax
             let wealth_tax = self.parameters.wealth_tax.as_ref()
@@ -314,14 +328,19 @@ impl Simulation {
                 .map(|p| variables::wealth_taxes::calculate_council_tax(hh, p))
                 .unwrap_or(hh.council_tax);
 
+            // Council tax enters total_tax for fiscal accounting, and housing costs
+            // for AHC. Both use council_tax_calculated so that reform scenarios
+            // (e.g. abolition or revaluation) flow through correctly.
             let total_tax = direct_tax + vat + fuel_duty + alcohol_duty + tobacco_duty
-                + cgt + stamp_duty + wealth_tax;
-            // HBAI net income: gross minus direct taxes and pension contributions, plus benefits.
-            // Excludes indirect taxes (VAT, duties) and transaction/wealth taxes (SDLT, wealth tax)
-            // to match the government HBAI definition used for poverty and distributional analysis.
-            let net_income = net_income_before_vat;
+                + cgt + stamp_duty + wealth_tax + council_tax_calculated;
+            // HBAI net income (BHC): gross minus direct taxes and pension contributions, plus benefits.
+            // Council tax is a housing cost subtracted in the AHC measure (not BHC), per HBAI convention.
+            // We adjust BHC net income for the *change* in council tax relative to the FRS-reported
+            // baseline, so that CT reform scenarios correctly shift households' disposable income.
+            let ct_adjustment = council_tax_calculated - hh.council_tax;
+            let net_income = net_income_before_vat - ct_adjustment;
             // Extended net income: subtracts indirect and wealth taxes for fiscal analysis.
-            let extended_net_income = net_income_before_vat - vat - stamp_duty - wealth_tax;
+            let extended_net_income = net_income - vat - stamp_duty - wealth_tax;
 
             // Modified OECD equivalisation scale (used by HBAI):
             // First adult: 0.67, additional adults (14+): 0.33, children (<14): 0.20
@@ -338,8 +357,8 @@ impl Simulation {
                 0.67 + (adults.saturating_sub(1) as f64) * 0.33 + (children as f64) * 0.20
             };
 
-            // AHC: subtract rent and council tax (housing costs), using HBAI net income
-            let housing_costs = hh.rent + hh.council_tax;
+            // AHC: subtract rent and council tax (housing costs), using calculated CT.
+            let housing_costs = hh.rent + council_tax_calculated;
             let net_income_ahc = net_income - housing_costs;
 
             HouseholdResult {