BNG UPDATE: Government to exempt ~50% of sites and unlock off-site flexibility

On 15 April 2026, the UK Government published its response to their consultation on improving the implementation of Biodiversity Net Gain (BNG) for minor, medium and brownfield development.

The headline is clear: BNG is being simplified where it is considered to be adding disproportionate cost, complexity, and delay—particularly on smaller sites.

What’s Changing (Expected Before 31st July 2026)

The Government will introduce secondary legislation to:

Introduce a new site-based exemption for sites which are 0.2 hectares or less
Remove the self-build and custom build exemption, anticipating many of these will fall within the 0.2ha exemption
Exempt temporary permissions (up to 5 years)
Amend the biodiversity gain hierarchy for minor development, allowing minor development to move straight to purchasing off-site biodiversity units before maximising on-site BNG
Change spatial risk rules to align with Local Nature Recovery Strategy (LNRS) areas only

What This Means In Practice

Development ≤0.2ha (red line boundary area) will be exempt from BNG. However, this exemption does not apply where priority habitats are affected (e.g. native hedgerows, etc). These sites will still be subject to BNG. The Government estimates this will remove BNG requirements from ~50% of residential applications. Many former self/custom build schemes will now fall under this new exemption.
Off-site BNG becomes a viable default (for minor sites). For non-exempt minor development, the biodiversity gain hierarchy will be relaxed, so that:

Off-site units will carry equal weight to on-site delivery
Small developers can avoid 30-year habitat creation and management obligations
Reduces risk of unviable or undeliverable on-site habitat creation
This is a significant shift toward cost certainty and programme control for minor development.

Easier access to off-site units: Spatial risk will now be assessed using LNRS areas only, replacing Local Planning Authority boundaries and National Character Areas. This widens the pool of available biodiversity units for developers when offsetting a given site and reduces cost inflation caused by artificial geographic constraints.

**What’s Not changing**

BNG is not being removed for all minor development
Sites under 0.2ha which impact priority habitats will still require BNG assessment
The mitigation hierarchy and national planning policy still applies. Sites under 0.2ha may still require Preliminary Ecological Appraisal (PEA) and Ecological Impact Assessment (EcIA), where relevant.
Planning permission can still be refused where impacts to biodiversity are unacceptable.
Irreplaceable habitats still require bespoke compensation

Transitional Position

Current BNG rules remain in force until legislation is enacted.

Any planning consent with a BNG condition will still require:

A Biodiversity Gain Plan
A Habitat Management and Monitoring Plan (if applicable)
Approval before commencement

What’s Next

Further consultation is now underway on brownfield residential exemptions (closing 10 June 2026)
Updated statutory metric tools and guidance are expected later in 2026
Transitional guidance is expected to clarify how current applications will be treated

Strategic Takeaways For Developers, Planning consultants, Architects and Local Authorities

These changes are a move toward more practical, delivery-focused BNG, meaning:

Fewer small sites caught by BNG, which can often be of negligible or the lowest biodiversity impact
Greater flexibility to use off-site solutions
Reduced long-term liabilities for small developers
Reduced volume and burden of BNG for Local Authorities

For most small schemes this means lower cost, less risk, and faster planning outcomes, provided the Government’s strategy is set correctly from the outset.