Key Proposed Changes
Defra has set out three significant proposals:
1. New 0.2 hectare area-based exemption
A new area-based exemption threshold of 0.2 hectares is proposed, replacing the current 25 square metre exemption. This would simplify how small sites are assessed and potentially reduce unnecessary BNG requirements on minor developments.
2. Removal of self-build and custom-build exemption
The current exemption for self-build and custom-build housing would be removed, meaning these developments would now be subject to standard BNG requirements.
3. Extended temporary development exemption
The exemption for temporary planning permissions would be extended, increasing the threshold from two years to five years. Developments with permissions up to five years would therefore be exempt from BNG obligations under the proposal.
What This Means for Rural Development
If implemented, these changes could significantly reduce the number of rural developments required to deliver BNG.
This is particularly relevant for:
- Temporary and permanent agricultural dwellings
- Agricultural buildings and farmyards
- Access tracks and rural infrastructure
- Replacement dwellings (including Mansell Case scenarios)
The introduction of a larger, clearer area-based exemption should also help applicants better understand when BNG applies, reducing uncertainty at the planning stage.
However, it is important to note that landscaping and biodiversity enhancements will still be expected in many cases, in line with local planning policy requirements.
Next Steps
Defra has confirmed its intention to bring forward the necessary secondary legislation before the summer recess in 2026, with the aim of changes coming into force before 31 July 2026, subject to parliamentary scheduling.
Until then, the current Biodiversity Net Gain legislation remains fully in effect.
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