What BNG requires
Under the Environment Act 2021, most planning permissions in England are granted subject to a general biodiversity gain condition. Before development starts, a biodiversity gain plan must be approved, showing that the development will achieve at least a 10% gain compared with the site’s value before development.
Biodiversity value is calculated with the statutory biodiversity metric, based on the type, size, condition and location of habitats. There is a simplified version for small sites.
How gains are delivered
- Onsite: creating or enhancing habitat within the development.
- Off-site: buying biodiversity units from a registered gain site, or creating habitat on other land you control.
- Statutory credits: a last resort, bought from the government at a deliberately high price.
Significant onsite gains and all off-site gains must be legally secured and managed for at least 30 years.
Exemptions
Householder applications, permitted development, de minimis development and some other categories are exempt. Since August 2026 there is also an exemption for sites of 0.2 hectares or less. See BNG: small sites now exempt.
Practical advice
BNG affects a site’s value and layout, so factor it in before you buy land or fix a design. A baseline habitat survey early on lets the scheme work with existing habitats rather than against them.
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Sources
This article is general information about planning in England at the date shown. It is not advice on any particular site, and the law and policy may have changed since. Please speak to us before relying on it.