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

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

Low case: -GBP 3.0bn. High case: +GBP 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 GBP 1bn.
  • Low case assumes removals quickly reduce hotel and support costs.
  • High case assumes detention and litigation dominate.
  • Reform's GBP 42bn decade claim is not mechanically adopted.

Fiscal build-up, central case

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

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

Main source groups

  • S1: Reform page gives 24,000 places, flights and savings claims.
  • S2: Operation Restoring Justice is the detailed party plan.
  • S3: Migration studies provide context, but operations costing relies mainly on official data.
  • S4: No Home Office impact assessment supports the claimed savings.
  • S5: PolicyLens treats decade savings as highly uncertain.