PolicyLens

Methodology note

Expand detention and deportation capacity: calculation note

Assumptions behind the Expand detention and deportation capacity scenario. Implementation detail is incomplete, so uncertainty is explicit.

View main policy page: Expand detention and deportation capacity

Central fiscal result

+£1.0bn - Net fiscal impact in 2027-28

Low case: -£3.0bn. High case: +£6.0bn. Positive numbers are fiscal costs or borrowing pressure. Negative numbers are Exchequer savings or receipts.

Scenario and baseline

  • 24,000 removal-centre places are built or procured.
  • Up to five deportation flights a day are attempted.
  • Treaty disapplication or withdrawal is politically contested.
  • Savings require actual lawful removals.

Affected population

  • Affected units are asylum seekers, Home Office systems and contractors.
  • Local areas hosting detention capacity are indirectly affected.
  • Legal services and courts face increased workload.
  • Accommodation providers lose demand if removals succeed.

Gross impact

  • Central early-year cost pressure is £1bn.
  • Low case assumes removals quickly reduce hotel and support costs.
  • High case assumes detention and litigation dominate.
  • Reform's £42bn decade claim is not mechanically adopted.

Fiscal build-up, central case

  • Detention-capacity and staffing costs: +£2.5bn
  • Flights, escorts and enforcement: +£0.7bn
  • Legal, courts and administration: +£0.8bn
  • Accommodation and support savings: -£3.0bn

Central net impact: +£1.0bn in 2027-28.

Behaviour and pass-through

  • Low case assumes high removal rates and lower future arrivals.
  • Central case assumes legal and diplomatic constraints slow delivery.
  • High case assumes capacity is built but removals lag.
  • Deterrence effects are not counted until evidenced.

Phasing

  • 2026-27: +£1.5bn. Preparation or partial implementation.
  • 2027-28: +£1.0bn. Main scenario year.
  • 2028-29: -£0.5bn. Behaviour and pass-through develop.
  • 2029-30: -£1.5bn. Steady-state uncertainty persists.

Main source groups

  • Dustmann and Frattini, "The Fiscal Effects of Immigration to the UK" (Economic Journal, 2014): Fiscal effects depend on employment, age and service use; asylum/deportation subgroups require separate data; useful background, but weak for costing deportation operations.
  • Migration Advisory Committee, "Migration Advisory Committee evidence base" (2024): Used to support the baseline, affected-population sizing or behavioural assumptions in the illustrative scenario.
  • Reform UK, "The Cost of the Boriswave" (2025): Reform estimates a £154bn discounted lifetime cost for a medium Boriswave settlement scenario; party-side context, not official costing.
  • Reform UK, "Operation Restoring Justice" (2025): Used to define the pledge wording, policy scope and implementation scenario being modelled.
  • Manacorda, Manning and Wadsworth, "The Impact of Immigration on the Structure of Wages: Theory and Evidence from Britain" (Journal of the European Economic Association, 2012): UK immigration had little detectable effect on native wages in the period studied; warns against overstating labour-market gains from removals.
  • Reform UK, "Our Policies" (2026): Reform pledges detention, deportation, treaty changes, no free housing or benefits, and stricter visas; current policy anchor.