BNG Calculatorv4.0 / JP039
Statutory Biodiversity Metric v4.0 (JP039)· Defra GOV.UK guidance, last updated 2 June 2026· NSIP extension live 2 November 2026· Reviewed 21 June 2026

On-site vs off-site vs statutory: which BNG route wins

Off-site units typically win on cost and risk for medium-distinctiveness deltas; on-site wins for small deltas under 3 BU; statutory credits never win, they are the punitive backstop.

Awaiting MCIEEM peer review · CIEEM (Chartered Institute of Ecology and Environmental Management)

Typical 1 ha greenfield end-to-end

Route A
On-site delivery
£35k-95k incl 30-yr mgmt
Route B
Off-site units
£45k-160k purchase
Route C
Statutory credits
£340k-2.6m floor (SRM x2)

Scoring matrix

Decision tree

Delta under 3 BU + low or medium distinctiveness + simple habitat creation: on-site. Delta over 3 BU, or high distinctiveness, or difficult habitat (Very High difficulty multiplier): off-site. Compelled trading-rule breach with no compliant supply: statutory.[S1]