Biodiversity net gain: what it means for landowners in England
Biodiversity net gain (BNG) is England's requirement, under the Environment Act 2021, for most new development to leave biodiversity at least 10% better than before. Since 6 August 2026, sites of 0.2 hectares or less are exempt unless priority habitat is affected. BNG affects what a site costs to develop, which feeds into land value. Wales takes a different approach.
Updated October 2026. General information, not legal or tax advice.
How does BNG affect my land's value?
If a site can't deliver the gain on site, the developer may need to buy off-site units or statutory credits, which costs money and reduces what they can pay for the land. Sites with low existing habitat value usually find BNG easier.
Does BNG apply to small sites?
Since 6 August 2026, non-major sites of 0.2 hectares or less are exempt unless the development affects priority habitat, and the separate self-build exemption has been withdrawn. Applications made before that date stay under the old rules. Larger sites still need to deliver at least a 10% gain.
Can my land earn money from BNG?
Possibly. Some landowners create habitat on land they keep and sell biodiversity units to developers, under long-term legal agreements. It's a separate decision from selling land for homes.
What happens in Wales?
Wales doesn't use England's 10% metric. Planning Policy Wales expects development to provide a net benefit for biodiversity, assessed differently.
This guide is general information for landowners in England and Wales. It isn't legal, tax or financial advice. Take advice from a solicitor, surveyor or accountant about your own situation.