Breadcrumb Home Planning Planning policy and guidance Biodiversity Net Gain Biodiversity Net Gain Biodiversity Net Gain (BNG) is a planning requirement that ensures certain types of development deliver an overall improvement in biodiversity through the creation, enhancement and long-term management of habitats. Where mandatory BNG applies, planning permissions are subject to a biodiversity gain condition. This requires development to achieve a minimum 10% increase in biodiversity value compared with the pre-development baseline and to maintain those gains for at least 30 years. Find out more information on the BNG for developers government webpage. What to submit with your planning application Applications that are subject to the biodiversity gain condition should be accompanied by sufficient information to demonstrate that the development can achieve the required BNG supported by the following information: A Biodiversity Net Gain Assessment A completed Statutory Biodiversity Metric submitted in Excel (.xlsm) format Baseline and proposed habitat plan For further details, see our Validation checklist For developments subject to mandatory BNG, where planning permission is granted, the following will be required before you commence any development: A final Biodiversity Gain Plan. See this Template A Habitat Management and Monitoring Plan for sites with significant onsite gains or offsite gains. See this HMMP Tools. For phased developments, details of how BNG will be delivered in each phase. A habitat plan/drawing showing baseline, retained, enhanced and created habitats, provided in PDF and GIS Shapefile formats, using the relevant UKHab classification methodology or GiGL data standards. Where an applicant considers that a proposal is exempt from the mandatory BNG requirements, the planning application should be accompanied by a Statement of Exemption setting out the relevant exemption and supporting justification. Where biodiversity gain is being delivered offsite or through statutory credits, the following will be required before you start the development: Copy of any agreements Proof of purchase Significant habitat Significant on-site habitat enhancements, together with any off-site gains, must be secured and managed for a minimum period of 30 years to ensure the target habitat condition is achieved and maintained. These biodiversity gains must be secured through appropriate legal mechanisms, which may include planning conditions, Section 106 agreements or conservation covenants. Find out more information on the legal agreements for BNG government webpage. Find out more information on the priority habitats government webapge. Monitoring over 30-year period OPDC is responsible for overseeing the monitoring of significant biodiversity gains secured through the planning process. Monitoring reports will be reviewed at specified intervals to assess progress and support the effective delivery of habitat creation and enhancement measures. Monitoring reports must be submitted to OPDC throughout the 30-year management period at the following years: 1, 2, 5, 10, 15, 20, 25 and 30 years. Biodiversity gain monitoring contribution To recover the cost associated with reviewing monitoring reports, a financial biodiversity gain monitoring contribution will be required. Where applicable, these costs will be secured as a one-off payment through a Section 106 agreement. Fee schedule Site Category Criteria Monitoring Fee Large site Site area above 2.5ha £13,921 Medium site Site area up to 2.5 ha or 10-49 homes £6,716 Medium site (with green roof) Site area up to 2.5 ha or 10-49 homes £7,679 Large Infrastructure/NSIPs Nationally Significant Infrastructure Projects Bespoke (case-by-case) Explanatory notes Monitoring charges for Nationally Significant Infrastructure Projects (NSIPs) and other major infrastructure proposals will be determined on a case-by-case basis, reflecting the scale, complexity and duration of monitoring requirements. The monitoring fees shown above are current at the date of publication (October 2026) and may be reviewed annually. Any future revisions will be published on this webpage. The fees do not include any financial penalties payable in the event of a breach or unsuccessful habitat enhancement.