Methodology note
Create regional mutual banks: note
Models create regional mutual banks in 2028-29. The estimate is illustrative and excludes wider package interactions.
Central fiscal result
+£2.5bn - Net fiscal impact in 2028-29
Low case: +£1.0bn. High case: +£8.0bn. Positive numbers are fiscal costs or borrowing pressure. Negative numbers are Exchequer savings or receipts.
Scenario and baseline
- Models create regional mutual banks by 2028-29.
- Baseline is current policy or published departmental plans.
- Central case uses published party or official anchors where available.
- Wider manifesto interactions are excluded unless stated.
Affected population
- Affected units are people, firms, households or providers depending on policy.
- Direct exposure follows the manifesto or government target group.
- Indirect exposure includes suppliers, workers, consumers and taxpayers.
- Weakest counts are widened in the low and high cases.
Gross impact
- Published anchor or scenario central is +£2.5bn in 2028-29.
- Gross costs or receipts are adjusted for behaviour and delivery risk.
- Tax, benefit or procurement offsets are separated in the fiscal build-up.
- The range is deliberately wider where implementation detail is thin.
Fiscal build-up, central case
- Gross programme or delivery cost: +£2.9bn
- Tax and receipt offsets: -£0.2bn
- Administration and evaluation: +£0.1bn
- Behavioural and pass-through effects: -£0.3bn
Central net impact: +£2.5bn in 2028-29.
Behaviour and pass-through
- Low case assumes stronger delivery or receipts than central.
- Central case applies moderate behavioural leakage and pass-through.
- High case allows weaker delivery, larger take-up or higher costs.
- Output effects follow incidence, capacity and investment channels.
- Distributional gains do not automatically imply GDP gains.
Phasing
- 2026-27: +£0.2bn. Phased implementation and take-up.
- 2027-28: +£1.4bn. Phased implementation and take-up.
- 2028-29: +£2.5bn. Phased implementation and take-up.
- 2029-30: +£2.5bn. Phased implementation and take-up.
Main source groups
- Banerjee and Duflo, "Do Firms Want to Borrow More?" (Review of Economic Studies, 2014): Some firms are credit constrained, so public finance can support investment when well targeted; relevant to development banks and business finance.
- Devereux, Griffith and Klemm, "Corporate Income Tax Reforms and International Tax Competition" (Economic Policy, 2002): Corporate tax changes can affect location, investment and reported profits; relevant to business and bank taxation.
- Institute for Fiscal Studies, "Green Party manifesto: a reaction" (2024): IFS highlighted scale and deliverability risks in Green spending and tax plans; supports sceptical treatment of claimed fiscal space.
- Local Government Association, "Green Party manifesto summary" (2024): Used to define the pledge wording, policy scope and implementation scenario being modelled.
- HM Treasury, "Spending Review 2025" (2025): Spending Review settlements define departmental baselines for new resource and capital commitments; used as the public-spending counterfactual.
- Green Party of England and Wales, "Manifesto for a Fairer, Greener Country" (2024): The manifesto defines the tax, spending, climate, housing and public-service proposals modelled here; used to define the scenario, not as an official costing.