New exemptions and revised thresholds for Biodiversity Net Gain from 6th August (England only)

The Defra guidance has been updated to reflect the changes and the CLA have updated the two relevant BNG guidance notes which can be found here.

It is important to note that these changes apply to planning applications submitted from 6th August. The new regulations do not apply to applications submitted before this date: applications and planning permissions already submitted will remain subject to the existing BNG legislation.

From 6 August 2026, BNG requirements will no longer apply to planning applications for where the site area is 0.2 hectares or below and does not harm a priority habitat. The 0.2 hectare area is applicable when the whole site falls under the threshold only and does not apply to 0.2 hectare of every site for development.

These developments will still be subject to environmental protections via the National Planning Policy Framework (NPPF) and wider regulatory requirements but will no longer need to demonstrate a 10% net gain either on or off site. Planning applications will be refused where a significant harm to biodiversity cannot be avoided, mitigated or compensated against, even on an exempt site.

From 6th August, it will no longer be possible to apply for exemption from BNG for self or custom build dwellings. It is anticipated that the new 0.2 hectare exemption will capture many of these developments. Self and custom-build applications submitted before 6th August but undetermined at the time of the removal of the exemption will remain exempt.

From 6th August, planning permission for temporary development which is for five years or less will also be exempt, unless a priority habitat is impacted. This recognises that delivery of BNG on these sites is limited due to their temporary nature.

Amendments have also been introduced for the biodiversity gain hierarchy. For non-major development, the hierarchy no longer favours on-site BNG but affords on-site and off-site the same level of recognition. Statutory credits remain as the last resort option.

Later in 2026

Following these changes to the BNG regime, we expect the following to also be amended in early 2027:

• Development with the primary objective to conserve or enhance biodiversity will be exempt from BNG.
• Development that enhances parks, playing fields and public gardens will also be exempt from BNG.
• Changes to the BNG metric.

In June, the CLA responded to a Defra consultation on a new exemption for development sites of up to 0.2ha from BNG.

The consultation asked whether a targeted exemption should be introduced, how brownfield residential development for this purpose should be defined, and what thresholds might be appropriate.

The CLA objected to the proposed targeted exemption for brownfield development as it will not solve the ongoing viability problem for residential brownfield development and risks undermining the off-site BNG market.

Recognising that there is scope for a better solution, the CLA has suggested an alternative approach for Defra. This would require residential brownfield sites up to 2.5ha to meet simpler BNG obligations through the delivery of less valuable units (such as grassland units). This approach would materially improve the viability and deliverability of these sites without undermining the off-site BNG market. Although it would not secure an exact like-for-like replacement plus 10%, it would still deliver a measurable benefit for nature, whereas the proposed targeted exemption would deliver none. We continue to monitor the situation and await a response from government on this proposal. 

Mandatory BNG for Nationally Significant Infrastructure Projects is expected to be implemented from 2 November 2026.

Defra will implement the same BNG requirements for all NSIP sectors and types of development, but there are some changes from original plans. There will also be flexibility on how the off-site regime will operate for these larger scale developments, allowing all BNG to be aggregated and delivered in any one of the Local Planning Areas affected by the project.

If you have any questions regarding these announcements, please contact the CLA for more information.