Biodiversity net gain: Key developments for landowners
Introduced by the Environment Act 2021 (“Act”) and, in large part, taking effect in February 2024 the biodiversity net gain regime (“BNG”) has introduced a new framework for both developers and landowners to engage with the provision and delivery of BNG.
How the BNG regime works
The biodiversity gain objective of the Act will be met when, in relation to development for which planning permission is granted, the post-development biodiversity value exceeds the predevelopment biodiversity value of the onsite habitat by at least 10%.
The latest exemptions
There are a number of statutory exemptions to the BNG requirements, most recently updated in August 2026. Where a development subject to a planning application satisfies the criteria of an exemption, that development will not be required to comply with the BNG requirements introduced by the Act. The most recent amendments to the BNG exemptions provide for the following:
- BNG does not apply to planning applications for developments where the site area within the red line boundary is 0.2 hectares or below.
- BNG does not apply to short-term developments if: the whole development is temporary; or planning permission is granted for 5 years or less.
Both of the above exemptions are not applicable where priority habitat is effected by the proposed development.
- The self-build and custom build exemption no longer applies for new planning applications made on or after 6 August 2026. This exemption has now been revoked.
Opportunities for off-site delivery
A notable exemption is for developments creating or enhancing habitats solely, or mainly, for the purpose of fulfilling the BNG planning condition for another development. The requirement for developers to seek to secure the 10% gain to meet the BNG objective ‘offsite’ where it is not possible to achieve it onsite means that many landowners have sought to dedicate parts of their land as offsite gain areas.
Whilst there are a number of statutory obligations which come with designating land in this way, most notably the requirement for the gain to be maintained for a period of 30 years, it does provide an opportunity for landowners to diversify land which may previously have not served an active ecological purpose.
BNG for nationally significant infrastructure projects
The BNG regime will apply distinctly to the Nationally Significant Infrastructure Project (“NSIP”) Regime with an adapted framework of obligations tailored to this specific type of development. BNG is targeted to come into effect on 2 November 2026 for NSIP projects. This regime will focus on the BNG boundary, not all of the habitats within the entirety of the area subject to the DCO. These projects will be able to use both onsite or offsite delivery as a starting point, meaning that there may be greater focus on offsite opportunities from the outset from the developers delivering these projects.
What this means in practice
Recent changes to the BNG regime and the forthcoming extension to nationally significant infrastructure projects may create further opportunities for landowners considering off-site habitat delivery. However, any arrangement should be assessed carefully in light of its long-term management requirements, commercial terms and impact on wider estate objectives.
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