The additionality position
Defra and Natural England guidance accepts stacked delivery where the BNG units demonstrate additionality beyond the intervention required for nutrient neutrality; the test is whether the BNG units would have arisen anyway from the NN intervention. Where the answer is yes, those units do not count for BNG.[S2]
Catchments permitting combined delivery
Solent (Hampshire and Isle of Wight), Stodmarsh (Kent), Tees Valley and the Broads currently see active combined delivery; supply is region-specific and tied to the catchment’s nutrient designation.
Why the discount is modest, not steep
The intervention often delivers both revenue streams from broadly overlapping habitat creation; the additionality test reduces gross unit yield by 15% to 30%. Buyers should require a written additionality opinion from the operator before contracting.