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

BNG spatial risk multiplier: in-LPA, neighbouring NCA, outside

Spatial risk discounts off-LPA delivery by 25% to 50%; a unit delivered outside the National Character Area is worth half what an in-LPA unit is worth.

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

The three bands

The discount applies to off-site units sourced outside the developer’s LPA; on-site delivery is by definition in-LPA at 1.0.[S1]

Interaction with trading rules

The trading rules require like-for-like or better habitat replacement; spatial risk applies before the trading rule test. A spatially-discounted off-site unit still has to satisfy the like-for-like rule on distinctiveness and broad habitat type, which can leave the developer with effectively fewer compliant supply options outside the LPA.

Worked equivalence

A 5 BU on-LPA target equivalent in outside-NCA supply: 5 / 0.5 = 10 BU. The developer must buy 10 outside-NCA units to compensate for 5 in-LPA units; combined with higher trading-rule friction, this typically pushes the rational route back to in-LPA supply or on-site.