Changes to Biodiversity Net Gain Exemptions in 2026

Following the NPPF consultation and subsequent Government announcements, Government has confirmed changes to the exemption options for developments that would otherwise be required to meet the Biodiversity Net Gain (BNG) condition.

We are updating Planning Portal to reflect these changes and ensure applicants have access to the latest information when completing their planning applications. The changes, which are set out in legislation, will affect how certain developments are assessed for BNG requirements.

New exemption options 

The following exemptions will be available for applications submitted on/after 6^th August 2026. 

• Developments of 0.2 hectares or below – A blanket exemption for all developments where the site area within the red line boundary is 0.2 hectares (2000 square metres) or below. 

• Temporary developments – An exemption for any development that is only permitted for a period of 5 years or less, including any earlier grant(s) of planning permission for the same temporary development i.e. the total period(s) cannot exceed 5 years. 

To be eligible for either of the new exemption options, there must also be no impact to any priority habitat, which are those listed by government under their Natural Environment and Rural Communities (NERC) Act powers. 

Removed exemption options 

The current exemption for self-build / custom build homes is being removed, and will not be valid on applications submitted on/after 6^th August 2026. 

It is expected that most of these developments will be covered by the new exemption for ‘developments of 0.2 hectares or below’ as detailed above. 

Changes to the Planning Portal 

We will be updating our system to account for the changes detailed above.

We plan to do this after business hours on 5^th August 2026, so that the changes are in place for 6^th August 2026. 

We will also be updating the validation logic shown once an exemption is selected, to ensure users clearly state their eligibility and consider the evidence they may need to provide. 

Additionally, for the retained ‘de minimis’ exemption option, we are adding content to direct users to the ‘developments of 0.2 hectares or below’ exemption where appropriate, as this will likely be simpler to evidence. 

Finally, we are making other minor changes to the Biodiversity Net Gain question to improve validation and error messaging. 

What does this mean for applicants and agents? 

If you have a draft application that you plan to submit on/after 6^th August 2026 and you feel it should be exempt from Biodiversity Net Gain, then you should: 

1. Review the Biodiversity Net Gain question prior to submission to ensure it is complete; 

2. Check that a valid exemption option has been selected; 

3. Answer any questions based on that exemption; and 

4. Ensure sufficient reasoning, justification and evidence has been provided. 

What does this mean for local planning authorities? 

Applications received from 6^th August 2026 onward may show the new exemption options. 

Any that still rely on the ‘Self-build and custom build development’ exemption should be reviewed and potentially deemed invalid. 

However, if the site area is 0.2 hectares or below a pragmatic route may be to advise the applicant/agent that the development is still exempt on that basis (if it does not impact any priority habitats). 

Please note that application data for Biodiversity Net Gain is only available in our current JSON data standard, not our legacy XML. To automate processing of this data, please get in touch with us and/or your IT supplier to discuss how you can update your systems to receive and utilise it.