Brownfield BNG exemption tracker
As of 3 October 2026 there is no brownfield exemption from mandatory biodiversity net gain in England. The government consulted between 15 April and 10 June 2026 on a targeted exemption for residential development on brownfield land with thresholds up to 2.5 hectares. It had not published a response when we last checked, so brownfield sites remain in scope. This page is updated when the position changes.
Key facts
- Consultation on a targeted residential brownfield exemption ran 15 April to 10 June 2026.
- Proposed thresholds: residential schemes on previously developed land up to 2.5 hectares.
- No government response published when checked on 3 October 2026.
- Brownfield sites remain in scope; the 0.2 hectare small sites exemption may still apply.
- Previously developed land often has very low baseline value, so deficits can be small but still require units.
Last checked: 3 October 2026
Status log
| Date | Status |
|---|---|
| 15 April 2026 | Consultation opened on a targeted exemption for residential brownfield development |
| 10 June 2026 | Consultation closed |
| 6 August 2026 | Separate changes commenced (0.2 hectare exemption, temporary development, minor development equal footing); brownfield not included |
| 3 October 2026 | No government response; brownfield remains in scope |
What was proposed?
An exemption for residential development on previously developed land below a size threshold, with safeguards for sites that have become valuable for nature, such as open mosaic habitat. The consultation asked about thresholds, the definition of brownfield and how to protect priority habitat.
What should developers do now?
Treat brownfield sites as in scope. Previously developed land usually has a low baseline, so the 10% uplift and any lost habitat produce a modest deficit that is met with fractional units. Sites of 0.2 hectares or less with no priority habitat affected are already exempt. If an exemption is introduced it will apply to applications made after its commencement date, so a live application should proceed on the current rules.
Why brownfield is harder than it looks
Previously developed land can hold open mosaic habitat on previously developed land, a priority habitat that often scores highly in the metric. A brownfield exemption would need to protect it, which is why the consultation asked about safeguards. Developers should survey early: a site that looks like rubble and buddleia can carry a high distinctiveness baseline.
What a future exemption might look like
- Residential development on previously developed land up to a size threshold (2.5 hectares was consulted on)
- Conditions protecting priority habitat and designated sites
- Application only to applications made after commencement
What to watch for in the response
- The size threshold adopted, if any
- How previously developed land is defined
- Safeguards for open mosaic habitat and other priority habitats
- The commencement date and transitional rules
Key takeaways
- No brownfield exemption yet
- Consultation closed 10 June 2026 with no response when last checked
- Brownfield sites remain in scope; the 0.2 hectare exemption may apply
- Survey early for open mosaic habitat
Frequently asked questions
Is open mosaic habitat on brownfield a problem?
It is a priority habitat. Negatively affecting it would remove the 0.2 hectare exemption and require like for like replacement.
Will the exemption be backdated?
Changes to date have applied to applications made on or after commencement, not retrospectively.
Does commercial brownfield benefit?
The consultation covered residential development.
How will I know when it changes?
This page and the exemption checker are updated when the government responds.
Does the 0.2 hectare exemption already help brownfield sites?
Yes, where the site is 0.2 hectares or less and no priority habitat is negatively affected.
Where is the consultation published?
On gov.uk under Defra consultations; the status log above is updated when a response is published.
Sources
Written by BNG Sourced by Green Acres BNG specialists and reviewed by Mike Dungait, Managing Director of Green Acres BNG, who has registered and manages two habitat banks. Indicative information, not legal or planning advice. Confirm with your ecologist and planning authority.
Related: BNG sourcing check, exemption checker, BNG unit prices, glossary, do I need BNG?, the 0.2 hectare exemption.
Need units for a live application?
Tell us your requirement and we'll start sourcing today.
Start the free sourcing check
One requirement, one point of contact, supply from across England.
Free for developers. Your details are only used to source your units.