You may have seen our article, in June, regarding the expected amendments to England’s mandatory Biodiversity Net Gain (BNG) regime which we were awaiting confirmation on. That confirmation has now landed, and the changes will come into force on 6 August 2026, changing which developments require BNG and how some applications are assessed.
While the core requirement to deliver a minimum 10% biodiversity net gain remains unchanged, the new regulations are intended to reduce costs and complexity for smaller developments while retaining protections for priority habitats. The key changes include:
New exemption for developments of 0.2 hectares or less
Planning applications for developments on sites 0.2 hectares or smaller are now generally exempt from mandatory BNG. However, this exemption does not apply where development would negatively affect onsite priority habitat. In those circumstances, BNG requirements continue to apply.
The Government estimates that the new threshold will remove a significant proportion of smaller planning applications from the mandatory BNG process.
New exemption for temporary developments
A further exemption has been introduced for temporary planning permissions of five years or less, provided the land will be reinstated at the end of the temporary use.
As with the new area-based exemption, this exemption cannot be used where the development would adversely affect onsite priority habitat.
Self-build and custom-build exemption removed
The previous exemption for small-scale self-build and custom-build developments has been withdrawn. As a result, planning applications for self-build and custom-build projects submitted on or after 6 August 2026 are now subject to the same BNG requirements as other qualifying developments, unless another exemption applies.
Biodiversity gain hierarchy relaxed for minor development
For minor developments that remain within scope of BNG, the biodiversity gain hierarchy has been amended. Previously, applicants were generally expected to prioritise onsite habitat creation or enhancement before relying on offsite biodiversity gains. From 6 August 2026, offsite biodiversity gains are treated on an equal footing with onsite habitat creation and enhancement for minor developments, providing greater flexibility where onsite delivery is constrained.
What has not changed?
The reforms do not alter the fundamental principles of mandatory BNG.
Developers must still deliver at least 10% biodiversity net gain for developments that remain within scope, use the statutory biodiversity metric, secure biodiversity gains for a minimum of 30 years and demonstrate compliance through the planning process where BNG applies.
For developers, landowners and planning professionals, these amendments simplify compliance for many smaller schemes while maintaining the overarching objective of ensuring that development contributes to nature recovery.
In our experience, where sites do not affect priority habitats, the changes will simplify the process and assist with viability, however, it should be kept in mind that these legislative changes are separate to, and do not change, any adopted Local Plan requirements for BNG which will vary from Council to Council.
BNG is something which we always “flag” early doors on projects and within development appraisals, and we work with great ecologists to find pragmatic solutions where possible, so if you have any queries as to how this may affect your proposals, get in touch!