Update on BNG exemptions: Small and Brownfield Site
The UK Government has released a significant update to Biodiversity Net Gain (BNG) on 15 April 2026 which materially change BNG requirements for small and brownfield sites.
Low Ecological Value Small Site:
- 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, woodland, certain ponds, grassland etc). These sites will still be subject to BNG.
- Removal of the self-build/custom build exemption
- Temporary permissions (up to 5 years) becoming exempt
- A revised biodiversity gain hierarchy for minor development, allowing developers to go straight to off-site units, avoid long-term (30-year) onsite habitat management obligations.
- Relaxed spatial risk rules, aligning only with Local Nature Recovery Strategy (LNRS) areas opposed to Local Planning Authority boundaries and National Character Areas currently used.
- This does not affect the ecological mitigation hierarchy, so these sites may still require Preliminary Ecological Appraisal (PEA) and Ecological Impact Assessment (EcIA), where relevant.
Brownfield Site:
Further consultation is now underway on brownfield residential exemptions (closing 10 June 2026)
When?
Changes are expected by 31 July 2026. The government will be providing transitional guidance to clarify treatment of current applications. Current BNG rules remain in force until the new legislation is enacted and any planning consent will require a Biodiversity Gain Plan approved before commencement