Biodiversity Net Gain (BNG) has been a mandatory requirement for most new developments in England since February 2024, requiring applicants to demonstrate a measurable 10% uplift in biodiversity value compared to pre-development baseline conditions. 

Two years on from its introduction, 2026 brought the most significant package of reforms to the BNG regime since it became law. Public sector bodies; whether as local planning authorities (LPAs), landowners, or undertaking their own capital projects should take note of what has changed and what is coming next.

What has changed and when

In July 2026, the government laid before Parliament new regulations giving effect to the first batch of BNG reforms, with the changes coming into force on 6 August 2026. These follow the government's April 2026 consultation response on improving BNG implementation for minor, medium and brownfield development.

The New 0.2-hectare exemption

The most significant change is the introduction of a new area-based exemption for developments with a red-line area of 0.2 hectares or less. The government estimates that this will exempt around 50% of residential planning permissions that were previously subject to mandatory BNG requirements. The exemption applies unless onsite priority habitat is negatively impacted. 

Critically, this new exemption applies only to new applications for planning permission made from 6 August 2026: existing applications and permissions already granted continue to be subject to the existing BNG legislation.

Temporary development exemption

A new temporary development exemption is also introduced for land which is to be reinstated within five years or less, again subject to the caveat that onsite priority habitat is not negatively impacted. 

This will be of particular relevance to public bodies managing temporary works or short-term infrastructure projects.

Removal of the self-build and custom build exemption

The existing exemption for self-build and custom build development is removed from 6 August 2026. 

In practice, many such applications are expected to fall within the new 0.2-hectare threshold, but schemes above that size will now be subject to mandatory BNG for the first time.

Changes to the Biodiversity Gain hierarchy for minor development

For minor developments that are not exempt from BNG (i.e. those above 0.2 hectares), the biodiversity gain hierarchy is amended so that offsite biodiversity gains are given the same priority as onsite habitat creation or enhancement. 

This provides greater flexibility for smaller sites where delivering habitat gains on-site is particularly challenging: for example, dense urban or brownfield sites. Statutory biodiversity credits remain the last resort in all cases.

BNG for Nationally Significant Infrastructure Projects

Looking ahead, it is currently expected that from 2 November 2026 BNG will become mandatory for Nationally Significant Infrastructure Projects (NSIPs) for the first time. A consistent 10% BNG requirement will apply across all NSIP types, with on-site and off-site gains treated equally (unlike the standard hierarchy applicable to planning applications). 

This is a significant development for public bodies involved in major infrastructure commissioning and delivery. The government has published guidance relating to BNG for NSIPs.

What comes next?

The government has confirmed that further reforms will follow, including: an exemption for development whose primary objective is to conserve or enhance biodiversity; an exemption for development that enhances parks, playing fields and public gardens; and changes to the statutory biodiversity metric (including the spatial risk multiplier). 

A separate consultation on a targeted exemption for certain brownfield residential development closed on 10 June 2026 and the government's response is awaited.

Additionally: Officer delegation of biodiversity gain plan submissions

It is worth noting that a further change of direct operational relevance to LPAs takes effect on 31 October 2026. The Town and Country Planning (Discharge of Local Planning Authority Functions) (England) Regulations 2026, comes into force on 31 October 2026. 

Schedule 1 to the Regulations, which lists the applications that must be determined by an officer rather than by committee, expressly includes the submission of a biodiversity gain plan.

In practice, this means that from 31 October 2026, biodiversity gain plan submissions cannot go to planning committee for determination. LPAs should review their schemes of delegation before that date to ensure they are compliant.

What does this mean for Local Planning Authorities?

Local planning authorities should update their processes to reflect the new exemptions and the revised biodiversity gain hierarchy for minor development from 6 August 2026, being mindful of the transitional arrangements that are in place. It will be important to understand how new exemptions should be applied, what exemptions will no longer be in force and what is considered 'minor' and 'major' development.

Whilst exempt developments will no longer need to satisfy the mandatory 10% BNG requirement, they remain subject to existing environmental protections. 

The government has confirmed it will update Planning Practice Guidance to support implementation of the August changes.

Conclusion

The 2026 BNG reforms have been described as representing a pragmatic recalibration of the regime in response to practical experience and stakeholder feedback.

There has been a reported focus on proportionality, for example exempting the smallest sites while expanding BNG to major national infrastructure. 

However, more changes bring about more work for LPAs and for those working in the planning regime to ensure that the correct position is being applied at all times and that there is clarity around what regulations should apply to each application.

In light of these changes and the further reforms anticipated in the months ahead, public sector bodies should review their current development pipelines, permitting processes and land management strategies.

We regularly advise LPAs, developers and landowners on BNG matters. If you have any questions, please do get in touch.