What is Biodiversity Net Gain?
Biodiversity Net Gain (BNG) is a mandatory requirement for most planning applications in England. It requires development to leave biodiversity in a measurably better state than prior to development, by achieving at least a 10% net gain in biodiversity value. Applicants should consider BNG at the earliest stage of their planning proposal so that habitat impacts are avoided or reduced wherever possible and any necessary enhancement can be planned effectively. Providing complete and accurate information at the outset will help avoid delay and support efficient determination of the application.
When Biodiversity Net Gain Applies
BNG applies to most residential, commercial and other development that requires planning permission. Some development may be exempt, and applicants should review the latest national guidance to confirm whether the requirement applies to their proposal. Where BNG is required, the biodiversity gain objective is secured through a statutory condition attached to the approved planning permission.
How is Biodiversity Net Gain Delivered?
To retain and enhance biodiversity, developers should consider the following options for achieving biodiversity gains:
- On-site- the creation or enhancing of habitats within the development site
- Off-site- the creation or enhancing of habitats elsewhere
- Statutory Biodiversity Credits-the purchasing of biodiversity credits from the government.
It is to be noted that the purchasing of Biodiversity Credits is to be treated as a last resort in the instance that the developer cannot meet the BNG requirement through on-site or off-site units.
Changes to BNG – August 2026
As of 6 August 2026, some key changes were introduced to the Biodiversity Gain (Town and Country Planning) (England) Regulations 2026.
For Planning Purposes, the key changes include:
0.2 Hectare Exemption
Biodiversity Net Gain no longer applies to a planning application where the area of the site, within the red line boundary, is 0.2 hectares or less and the proposed development does not impact on-site priority habitat.
If the area within the red line boundary is under 0.2 hectares but is deemed to still impact priority habitat, Biodiversity Net Gain still applies.
Exemption for Temporary Development
Biodiversity Net Gain is now exempt where the whole development is temporary and meets the following criteria:
- Planning permission is required for a period of five years or less;
- The development/use is to be removed/ discontinued and the land re-instated to its former condition within that period
- No priority habitat is impacted by the temporary development.
This new exemption also includes an anti-avoidance provision. This means that permission for temporary developments cannot be extended and surpass the five year limit whilst still claiming the BNG exemption.
Removal of the self build/ custom-build exemption for new applications
Prior to these changes, qualifying self and custom-build development was exempt from providing Biodiversity Net Gain. For new applications submitted on or after the 6 August 2026, this exemption no longer applies.
For planning applications submitted prior to the 6 August 2026, the exemption remains in place and certain later variations can retain the exemption.
BNG Hierarchy Relaxed for Minor Developments
From 6 August 2026, BNG applicable non-major/ minor development can now either deliver net gain on site or use registered off-site biodiversity units without first having to demonstrate that on-site net gain is not possible.
In simple terms, On site and Off-site BNG delivery is now placed on an equal footing for small sites. A developer can choose the off-site option for the delivery of BNG from the outset without first have to exhaust the on-site option.