Biodiversity net gain exemptions: the full gov.uk list for 2026

The exemptions

• Applications made before 12 February 2024. gov.uk: any planning applications for developments made before that date are exempt.
• Small (minor) developments applied for before 2 April 2024. gov.uk: any planning applications for small developments made before that date are exempt.
• Developments of 0.2 hectares or below. gov.uk: from 6 August 2026, BNG does not apply to planning applications for developments where the site area within the red line boundary is 0.2 hectares or below.
• Householder applications, including home extensions, conservatories and loft conversions, as defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
• The de minimis rule, where the development impacts less than 25 square metres, that is 5 metres by 5 metres, of on-site habitat, or less than 5 metres of on-site linear habitats such as hedgerows.
• Temporary developments. gov.uk: from 6 August 2026, BNG does not apply to short-term developments if the whole development is temporary and planning permission is granted for 5 years or less.
• Self-build and custom build, where planning permission was obtained before 6 August 2026.
• Off-site BNG gain sites, that is developments creating or enhancing habitats solely or mainly to fulfil a BNG planning condition.
• High-speed rail, for development that is part of, or ancillary to, the high-speed railway transport network.
• Crown development and permitted development rights, as exempted under the Environment Act 2021.

Exempt does not mean nothing to do

Two things still bite when a development is exempt from BNG. First, most authorities expect an exemption statement or the relevant declaration with the application, and getting it wrong is a validation problem rather than a planning one. Second, BNG is not the whole of ecology: protected species, priority habitats, tree protection and local plan biodiversity policies all apply independently of whether the statutory 10 percent does. A site with an active badger sett or a bat roost has exactly the same obligations whether or not it clears the 0.2 hectare threshold.

Before you rely on an exemption

1. Measure the red line area properly, not the developable area. The 0.2 hectare test is stated by gov.uk by reference to the site area within the red line boundary.
2. Check the date your application was made, since several of the exemptions are date-based.
3. Read the gov.uk exempt developments page in full rather than a summary, including this one, and check the local planning authority's own validation requirements.
4. Get it confirmed in writing where an exemption is load-bearing for your programme. A wrongly claimed exemption discovered at validation costs a survey season.

Exemptions are quoted from gov.uk guidance on BNG exempt developments, linked in the sources below. Guidance in this area has changed repeatedly, so check the current page before relying on it.