Biodiversity Net Gain (BNG)
Introduction
Biodiversity Net Gain is an approach to development that leaves biodiversity in a measurably better state after development than before, after first avoiding and minimising harm.
All developments (except for some exceptions, such as householder applications) have to deliver 10% BNG. This requirement does not replace, but is in addition to, the existing policy and legal requirements related to biodiversity and development
To measure BNG and assess the impacts of planning applications Defra’s Biodiversity Metric (or for smaller sites the small sites metric) should be used.
Biodiversity Net Gain: Good practice principles for development (published by CIEEM) should be followed when designing developments and preparing planning applications. Further advice can be obtained from the council via our pre-application advice service.
Planning applicants will need to provide information on the biodiversity value of their application site and how they plan to deliver 10% BNG as part of their application. Details can be found on our validation webpages.
In most cases, BNG should be provided on the development site (particularly where proposals impact designated sites, irreplaceable habitats or priority habitats), but in some cases, and in agreement with the council, it may be necessary to provide the net gain off-site. This could be on land within the planning applicant’s control or via another landowner or BNG broker. The council has worked with the Gloucestershire Nature and Climate Fund to enable a supply of potential off-site BNG delivery locations.
Government guidance on the BNG process is available at: Developer guidance
Gloucestershire Local Nature Recovery Strategy and BNG
Local Nature Recovery Strategies are spatial strategies introduced by the Environment Act 2021 which aim to guide nature restoration to contribute to the expansion of the Nature Recovery Network across England. The strategies help to understand where nature recovery actions in the area would be most effective and will make the greatest collective impact for biodiversity. The Gloucestershire Local Nature Recovery Strategy (LNRS) establishes biodiversity priorities and maps proposals for actions to push the recovery of nature and improvement of biodiversity across the county. Gloucestershire County Council was appointed by Defra as the Responsible Authority for the Gloucestershire LNRS which was published on the 13th of February 2026.
Developers should use the LNRS to design green infrastructure that delivers for people and positively impacts nature and its recovery across the county. The LNRS should also be used by planning applicants when determining how and where to deliver BNG as part of their development, including to inform the location of off-site BNG. Development projects which create, enhance or recover habitat in locations mapped in the LNRS will generate a higher biodiversity value within the metric than they would in other locations which are not mapped within the LNRS. The BNG statutory metric user guides contain guidance on how to assign strategic significance for habitats in the biodiversity metric using the LNRS.
Planning applicants should refer to the relevant guidance for BNG to ensure that the LNRS and strategic significance have been appropriately considered and recorded within their BNG proposals prior to submitting their application to the local planning authority. Further information published by Local Government Association Planning Advisory Service provides guidance on how strategic significance should be recorded after the publication of the LNRS. Guidance documents are periodically updated to reflect changes in national and local legislation, policy and guidance.
In conjunction with referring to the LNRS, applicants may need to consult with an ecological professional to decide on the most appropriate creation, enhancement or restoration measures or to inform habitat and land management plans. Alternatively, applicants can engage with CDC’s pre-application advice service: Get advice on your planning application - Cotswold District Council.
Condition compliance
Further details on BNG must be submitted as part of the “statutory biodiversity gain condition” and development cannot commence until that condition has been discharged. Please note that this condition, in line with the relevant legislation, will not appear on your decision notice as a condition (only as an informative), but it will still apply. Information on how to discharge this condition is available below:
How to discharge the biodiversity gain condition - pdf - 119 Kb
Habitat Management and Monitoring Plans (HMMPs)
These HMMPs should normally follow the template provided by Natural England.
It is important that all HMMPs clearly set out the timeframes and deadlines for action and monitoring to enable the Council to review the success of BNG delivery. These key dates include –
- Commencement date – the date upon which the Habitat Creation and Enhancement Works have commenced
- Completion Date – date when the Habitat Creation and Enhancement Works have been completed
- Monitoring Dates – usually at years 1, 2, 5, 10, 15, 20, 25 and 30 following completion
All HMMPs should confirm that the relevant aerodromes or airfields have been consulted – this is to ensure that any proposed habitat creation will not lead to an increased risk of bird strike.
S.106 agreements and financial contributions to Council monitoring costs
Cotswold District Council can secure biodiversity net gain through two primary mechanisms: section 106 legal agreements and planning conditions. Template s106 legal agreements will be published on the Council’s website shortly. The mechanism required for your development will depend on the type of biodiversity gains being delivered:
- A planning condition will be used to secure non-significant on-site gains.
- A s106 legal agreement will be used to secure monitoring fees for on-site significant gains.
- A s106 agreement will also be required to secure monitoring fees and a 30-year management strategy for all off-site gains, regardless of their significance.
Purchasing off-site units from a registered habitat bank will not require you to enter into a section 106 legal agreement because the habitat bank will already have an agreement in place with the Council.
It is important that significant on-site and all off-site BNG is monitored and this will form part of the agreed Habitat Management and Monitoring Plans (HMMPs), which will set out the monitoring responsibilities of the land-owner or developer.
The Council will need to ensure that this monitoring takes place and that they have fully reviewed all monitoring reports, assisting landowners and developers to deliver the planned enhancements to biodiversity. To cover the cost of this work, the Council will require developers or landowners to make a financial contribution. Payments for this financial contribution will be secured in the relevant s.106 agreement.
Potential Habitat Banks
The Council is preparing guidance to support landowners who wish to provide habitat banks. Until such time as that guidance is completed, potential habitat bank providers may wish to look at some of the useful guidance provided by other Councils, for example South Oxfordshire District Council.