Biodiversity Net Gain changes from 6 August 2026: what developers need to know
The Government has made a series of amendments to Biodiversity Net Gain (BNG) that came into force on 6 August 2026, introducing new exemptions for the smallest developments while also removing some existing ones. The changes are intended to reduce the administrative burden on minor developments, although many schemes will still need ecological input to determine whether an exemption actually applies.
So, what has changed and what does it mean in practice?
A new 0.2 hectare exemption
Perhaps the most significant change is the introduction of a new site area threshold.
Planning applications submitted on or after 6 August 2026 for sites 0.2 hectares or smaller will generally be exempt from mandatory BNG requirements.
However, there is one important caveat.
The exemption does not apply where development would negatively affect an onsite priority habitat. If priority habitat is present and impacted, the development will still need to comply with the full BNG process regardless of site size.
This means that even very small sites may still require an ecological assessment to establish whether priority habitats are present before assuming that BNG is not required.
Existing de minimis exemption remains
The existing de minimis exemption is unchanged.
Developments affecting less than 25m² of non-linear habitat or less than 5 metres of linear habitat, such as hedgerows, remain exempt from mandatory BNG requirements.
Temporary developments now exempt
A new exemption has also been introduced for temporary developments.
Where planning conditions require both the removal of the development and the reinstatement of the land within five years, mandatory BNG will no longer apply, provided priority habitats are not adversely affected.
Self-build exemption removed
One notable change is the removal of the previous exemption for self-build and custom-build developments.
Instead, these projects will now be treated in the same way as any other planning application. Smaller self-build schemes may still qualify for the new 0.2 hectare exemption, but larger sites will generally be expected to deliver BNG in the normal way.
Minor (“small”) sites can choose the offsite option in the first instance
There is also a modification to the biodiversity gain hierarchy for minor development, meaning that minor sites which aren’t exempt from BNG (e.g. over 0.2 hectares) can choose to go straight to delivering BNG offsite.
A small development is defined as:
- a residential development where the number of dwellings is between 1 and 9 on a site of an area 1 hectare or less, or if the number of dwellings is unknown
- the site area is less than 0.5 hectares
- a commercial development where floor space created is less than 1,000 square metres or total site area is less than 1 hectare;
- a development that is not the winning and working of minerals or the use of land for mineral-working deposits
- a development that is not waste development
Existing applications are unaffected
These amendments are not retrospective.
Planning applications submitted before 6 August 2026 will continue to be assessed under the current BNG legislation. In most cases, only applications made on or after that date will benefit from the new exemptions.
What does this mean for developers?
For many small developments, these changes will simplify the planning process and remove the need to prepare a Biodiversity Gain Plan.
However, it is important not to assume that every site below 0.2 hectares is automatically exempt. Ecological constraints, particularly the presence of priority habitats, can still trigger the need for full BNG compliance.
Early ecological advice remains valuable, not only to establish whether an exemption applies but also to identify protected species, priority habitats and other planning constraints that sit outside the BNG process.
Need advice?
If you're unsure whether your development qualifies for one of the new exemptions, our ecologists can help assess your site and advise on the most proportionate route through the planning process.
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Source: https://defraenvironment.blog.gov.uk/2026/07/14/biodiversity-net-gain-amendments-and-transitional-arrangements-published/ published 14/07/2
