Biodiversity Net Gain reforms announced – what planning applicants need to know
Johannah Legg, Ecological and Natural Resources Advisor, explains why the latest Biodiversity Net Gain reforms could be important for those preparing a planning application, and why early ecological advice remains key.
The Government has confirmed a number of changes to the Biodiversity Net Gain (BNG) regime, with new legislation coming into force on 6 August 2026. The changes are intended to reduce the administrative burden for smaller developments while maintaining protection for England's most valuable habitats.
For landowners, developers and planning applicants, these amendments could have a significant impact on whether BNG is required and how it is delivered.
What is changing?
New exemption for very small developments
From 6 August 2026, most developments on sites of 0.2 hectares or less will generally be exempt from the mandatory BNG requirement.
However, this exemption does not apply where priority habitat is present on the site and would be adversely affected. In these circumstances, BNG requirements will still apply.
For many small rural developments, extensions and modest redevelopment schemes, this may remove the requirement to deliver mandatory BNG, prepare a Biodiversity Gain Plan and undertake the associated metric calculations.
Temporary developments
A new exemption has also been introduced for developments with a temporary planning permission of five years or less, provided the land will be fully reinstated afterwards.
Again, this exemption is unavailable where priority habitat would be impacted.
Self-build exemption removed
While new exemptions have been introduced, the Government has also confirmed that the previous exemption for self-build and custom-build housing will be removed.
This means qualifying self-build developments submitted after the implementation date will generally need to comply with mandatory BNG in the same way as other residential developments.
Transitional arrangements
Importantly, the changes are not retrospective.
Applications submitted before the new regulations come into force will continue to be assessed under the current rules, while applications submitted afterwards will follow the amended regime. Defra has published transitional arrangements to clarify which set of regulations applies.
What does this mean for planning applications?
If you are preparing a planning application over the coming weeks, the timing of submission may become an important consideration.
For example:
Some small developments may benefit from the new 0.2-hectare exemption if submitted after the regulations come into force.
Conversely, self-build proposals may lose their current exemption if submitted after 6 August 2026.
Regardless of whether BNG applies, sites should still be reviewed by an ecologist to identify any priority habitats, protected species constraints or other ecological considerations.
How Stags can help
At Stags, our Planning, Design and Ecology teams work closely together from the earliest stages of a project, ensuring ecological considerations are integrated into the design and planning process rather than addressed later in the application. This coordinated approach helps identify potential constraints early, minimise delays and ensure planning applications are supported by proportionate ecological advice.
Whether it is a single dwelling, agricultural development or a larger residential scheme, we can advise on how the new BNG exemptions may apply and guide you through the most appropriate route to securing planning permission.
Contact Stags Professional Services on 01823 653424 to speak with your local planning specialist and get clear, practical guidance on how to move your project forward with confidence.
Johannah Legg, Ecological and Natural Resources Advisor, explains why the latest Biodiversity Net Gain reforms could be important for those preparing a planning application, and why early ecological advice remains key.
