November 2026

Biodiversity Net Gain exemption for smaller brownfield developments announced in Autumn Budget

The Government has announced plans to exempt smaller brownfield housing developments from mandatory Biodiversity Net Gain (BNG) requirements, in a move designed to reduce development costs and accelerate housebuilding.

The measure was confirmed by Chancellor John Healey in the recent Autumn Budget. Under the proposals, residential developments on brownfield sites of up to 1.5 hectares in England will no longer be required to demonstrate a 10% biodiversity net gain. The exemption aims to improve the viability of smaller brownfield schemes, support housing delivery, and encourage the regeneration of disused urban sites.

The Department for Environment, Food and Rural Affairs consulted earlier this year on a possible brownfield BNG exemption, considering thresholds from 0.5 to 2.5 hectares. The commitment to 1.5 hectares moves the consulted exemptions forward, but further details are yet to be announced.

Further details, including arrangements for mixed-use sites, or potential safeguards for Priority Habitats, have yet to be confirmed. The timescale for amending the legislation has yet to be announced, so it is as yet unclear when these changes will take effect.

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Brownfield site in Kent that Aspect Ecology is currently working on