Biodiversity Net Gain is a way of ensuring development has a measurable positive impact on biodiversity by comparing the biodiversity value of the site pre-development with the biodiversity value of the site post development.
The Environment Act November 2021 mandates the provision of 10% Biodiversity Net Gain (BNG) on the majority of development sites for 30 years. This came into force on 12 February 2024 and will apply to outline, full and temporary applications. From this date, major development (unless otherwise exempt) will have to deliver net gains for biodiversity leading to positive outcomes for nature, better places for local communities, and more consistent and transparent requirements for developers. Further information is available on the Defra website. The exempt developments are set out in the regulations. Planning permission can now only be granted where a 10% gain is made, as this is a mandatory requirement.
BNG for small sites came into force on 2 April 2024. The definition of small sites is summarised below. Small site development includes:
- Residential development where the number of dwellings is between 1 and 9, or if unknown the site area is less than 0.5 hectares
- Commercial development where floor space created is less than 1,000 square metres or the total site area is less than 1 hectare
The Government has just published amendments to the BNG regulations relating to exemptions 14.07.26. The date the changes come into force is Thursday 6 August 2026.
Read the small sites metric and user guide
Links to specific guidance are listed below. In addition, the Future Homes Hub and the Planning Advisory Service (PAS) have launched ‘BNG Online’. This is a free digital resource offering practical guidance and advice on complying with BNG. It also directs users to a range of digital tools that can help to meet the requirements.
- The Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026
- The Explanatory Memorandum to The Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026 No. 790
- Commencement Regulations – The Environment Act 2021 (Commencement No. 8 and Transitional Provisions) Regulations 2024 No. 44 (C.4)
- The Biodiversity Gain Site Register Regulations 2024 No. 45
- The Biodiversity Gain Site Register (Financial penalties and Fees) Regulations 2024 No.46
- The Biodiversity Gain Requirements (Exemptions) Regulations 2024 No. 47
- The Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations 2024 No. 48
- The Biodiversity Gain (Town and Country Planning (Consequential Amendments) Regulations 2024 No. 49
- The Biodiversity Gain (Town and Country Planning) (Modifications and Amendments) (England) Regulations 2024 No. 50
- Make on-site biodiversity gains as a developer
- Make off-site biodiversity gains as a developer
- Authorise an agent to act your behalf form
- Record allocation of off-site biodiversity gains to a development
- Record allocation of off-site biodiversity gains form
- Register a biodiversity gain site
- Register a biodiversity site and allocate to a development
For specific information relating to Kent please visit the Kent Nature Partnership website, Kent County Council also has a page dedicated to Biodiversity Net Gain including guidance on the planning application process.
Kent County Council has produced interim guidance including the approach to be taken in assessing the strategic significance of a habitat when completing the statutory metric.
This guidance will be replaced by the Local Nature Recovery Strategy (LNRS) which is due for completion 2025. KCC has also produced a BNG site register which identifies potential, off site delivery sites. Both can be found on the Making Space for Nature website.
PermalinkThe council has produced some informal guidance to help developers successfully implement BNG as part of their proposals. The council recommends developers refer to this guidance early in the process when formulating schemes.
- Timeline for Biodiversity Net Gain (BNG) in the Planning Process
- Thanet District Council Guidance for Establishing Independent Habitat Banks