Biodiversity net gain: exempt developments
A guide to the types of development that will be exempt from the mandatory biodiversity net gain (BNG) requirements.
Applies to England
BNG rules do not apply to the following types of development.
Planning applications鈥痵ubmitted before mandatory BNG听
Any planning applications for developments made before 12 February 2024 are exempt from BNG.
Small听developments
Any planning applications for听small (鈥榤inor鈥�)听developments听made before 2 April 2024 are听exempt听from BNG.听
Read听what听constitutes a听small development.
Variations of planning permission
Transitional arrangements also apply for variations to existing planning permissions. For example,听where the original planning permission was not in scope of BNG, BNG will not apply to future variations听in most cases.
There is more information in the planning practice guidance.
Householder applications
These are small projects householders carry out in their own homes. They can include:听听
- home extensions听
- conservatories听
- loft conversions听
These applications are defined within .
Developments of听0.2 hectares or below
From听6听August 2026,听BNG does not apply to听planning applications for developments听where the site area within the听red line boundary is听0.2 hectares or听below.
Developments subject to the 鈥榙e minimis鈥� rule
BNG does not apply to developments that impact less than:鈥�
- 25 square metres (5m by 5m) of on-site habitat鈥� within the red line boundary
- 5 metres of on-site linear habitats such as hedgerows
This rule is called the 鈥榙e minimis鈥� exemption.
Temporary听developments
From听6听August 2026, BNG does not apply to short-term听developments听if:
- the whole development is temporary
- planning permission is granted for 5 years or less
If there is an impact on听priority habitat on-site, the exemptions for the听following developments do not apply and BNG must be met:听听
- developments of 0.2 hectares or below听听
- developments subject to the 鈥榙e minimis鈥� rule听
- temporary developments
A development 鈥榠mpacts鈥� a habitat if it鈥�decreases its biodiversity value.
Self-build and custom build applications
The self-build and custom build听exemption no longer applies听for new planning applications听made on or after听6听August 2026.
Your self-build or custom build is exempt from BNG if you applied听for:
- planning permission before听6听August 2026听
- a variation of听planning permission on or after听6 August 2026, and the original planning permission was exempt
Find out more about what qualifies as self-build听and custom housebuilding.
Sites created for off-site BNG听gains
Developments creating or enhancing habitats听solely听or mainly听for the purpose of fulfilling the鈥�BNG鈥痯lanning condition for another development are exempt.
This is because these gain sites听are听created to offset听the BNG for another development.
High speed rail transport network
An exemption applies to developments that are part of, or ancillary to, the high-speed railway transport network. This includes connections between all, or parts of the places listed in .
Other exemptions
The following are exempt by the :
- urgent crown developments听
- developments that are granted planning permission by a development order (including permitted development rights)
Further听information
There is more听guidance from Ministry of Housing, Communities and Local Government听(MHCLG), including听on:
- variations听of planning permission
- the听鈥檇e minimis鈥� exemption听鈥撎齣ncluding听what听evidence听you听may need to听submit听to show this exemption applies
- temporary development exemption
Give feedback
.
Updates to this page
-
Updated guidance on self-build and custom build applications. The self-build and custom build exemption no longer applies for new planning applications made on or after 6 August 2026.
-
Clarified that any existing planning applications made before 12 February 2024 are exempt from biodiversity net gain (BNG), including small developments. Clarified that for variations of planning permission, where the original planning permission was not in scope of BNG, mandatory BNG will not apply to future variations. Clarified the exemption for developments subject to the 鈥榙e minimis鈥� rule. Added a link to the list of priority habitats and species in England. Self-build and custom build applications made after 6 August 2026 are no longer exempt from BNG rules. The new exemption for planning applications for developments of 0.2 hectares or below and temporary developments is in place from 6 August 2026.
-
Updated to add clarity about what criteria a development must meet to qualify for exemption as a self-build or custom build. A link has been added to guidance on self-build and custom housebuilding.
-
Removed 'small developments' from the exemptions list as small developments are subject to BNG from 2 April 2024.
-
Updated box at top of page to state that biodiversity net gain (BNG) is mandatory from 12 February 2024 and removed the 'draft guidance' label. Also provided more clarity around the 'Developments below the threshold' exemption. Added other exemptions.
-
Updated to clarify that a small site does not fall into the category of a major development, as defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
-
First published.