Guide · England · Planning
For small builders, small developers and self-builders. The exemptions changed on 6 August 2026, and the 28 October 2026 Budget announced another one that is not yet in force. This page sticks to what GOV.UK has published.
Last updated 2 November 2026. Based on the GOV.UK exemptions guidance (last updated 6 August 2026) and the Budget 2026 document.
Not legal or planning advice. Check the GOV.UK guidance and speak to your planning authority or a planning consultant about your site.
Priority habitat: if the development impacts priority habitat on site, the 0.2 hectare, de minimis and temporary exemptions do not apply and BNG must be met.
Source: GOV.UK — Biodiversity net gain: exempt developments (Defra, last updated 6 August 2026).
The self-build and custom build exemption no longer applies to planning applications made on or after 6 August 2026. Your self-build is still exempt if you applied for planning permission before 6 August 2026, or if you apply for a variation on or after that date and the original permission was exempt. For a new application, a plot of 0.2 hectares or below may fall under the small-site exemption instead.
The Budget on 28 October 2026 said the government will introduce an exemption from BNG for residential brownfield developments on sites up to 1.5 hectares in England. The full consultation response and impact assessment will be published in due course and will set out the timeline. There is no start date yet, and the detailed scope has not been published. Until it is, plan on today's rules.
For the rest of the Budget, see what the 28 October 2026 Budget changed for people building or extending a home.
Sources: Budget 2026 document (HM Treasury, 28 October 2026); commentary from Forsters LLP (29 October 2026).
If BNG applies, in ConstructionPro.io you add the ecologist's fee and any off-site units you buy as cost lines with their dates. The app doesn't calculate biodiversity units, check whether BNG applies or check compliance.
If your planning application was made on or after 6 August 2026 and the site within the red line boundary is 0.2 hectares or below, BNG does not apply — unless the development impacts priority habitat on site. Check the GOV.UK guidance and ask your planning authority.
Not for new applications. The self-build and custom build exemption no longer applies to planning applications made on or after 6 August 2026. A self-build is still exempt if planning was applied for before 6 August 2026, or for a later variation where the original permission was exempt. A self-build plot of 0.2 hectares or below may instead fall under the small-site exemption.
BNG does not apply where a development impacts less than 25 square metres of on-site habitat or less than 5 metres of on-site linear habitat such as hedgerows, unless it impacts priority habitat.
No. The 28 October 2026 Budget said the government will introduce an exemption for residential brownfield developments on sites up to 1.5 hectares in England. The timeline will be set out in the full consultation response, published in due course. Until then, today’s rules apply.
No. In ConstructionPro.io you add the ecologist’s fee and any off-site units you buy as cost lines with their dates. The app doesn’t calculate biodiversity units, check whether BNG applies or check compliance.
Related: NPPF station-area density for self-builds and the UK market overview.