Biodiversity Net Gain

The information below sets out our response to some common issues and questions about our approach to Biodiversity Net Gain (BNG) for developers and those with an interest in the subject.

What is Biodiversity Net Gain?

Biodiversity net gain (BNG) is an approach introduced under the Environment Act 2021, to ensure that developments and land management leave the natural environment in a better state than it was beforehand. It contributes towards nature recovery by helping to deliver habitat creation and enhancements as part of the design of new development.

Why Does It Matter?

Measurable BNG provides an opportunity to improve the connectivity of nature on a landscape scale, by promoting bigger, better, and joined up habitats. We need BNG because the State of Nature Report (2023) shows that the abundance of 753 terrestrial and freshwater species have declined by approximately 19% in the UK since 1970, and nearly 1 in 6 species (16%) are now threatened with extinction. A collective strategy is therefore necessary to restore and conserve biodiversity.

FAQs and Key Considerations


The law mandates delivering a minimum biodiversity uplift of at least 10% in addition to standard biodiversity mitigation and compensation measures. Our  Emerging Local Plan supports a target of 20% BNG.

Mandatory BNG applies to all Town and Country Planning Act (1990) developments, excluding exemptions and small sites, starting from 12 February 2024.

BNG will become mandatory for minor sites on 2 April 2024.

Exemptions include specific development types such as householder applications, biodiversity gain sites, and small-scale self-build and custom housebuilding. However, developments exempt from mandatory net gain still require opportunities for biodiversity enhancements in accordance with local and national policies.

Mandatory national BNG does not apply to permitted development and prior approval applications.

Find further details on exemptions here.

BNG is measured using the Statutory Biodiversity Metric, a tool that guides designs and land management decisions to support biodiversity better. The metric divides the baseline assessment into three different unit modules based on habitat type. These can be ‘area’, ‘hedgerow’ or ‘watercourse’ unit modules, each subject to its 10% net gain requirement. The catalogued habitats are converted into biodiversity units, which are used as proxy for habitat value. Habitat value is determined based on distinctiveness, extent, condition, and strategic significance.

For more information on how BNG is measured, please visit the User Guide.

Strategic significance is the local significance of a habitat based on its location and habitat type. Assessors should assign a strategic significance category within the Metric for each individual habitat parcel both at baseline and at post-intervention. In the absence of the Local Nature Recovery Strategy (LNRS), assessors should use published plans, strategies or polices which are relevant to the habitat’s location to determine the strategic significance of the habitat and reference the relevant documents in their justification.

Further local guidance on Strategic Significance will be updated within our guidance as soon as possible.

For all applications not classed as exempt or small, the statutory full biodiversity metric is used, completed by a competent ecologist. All sites containing a watercourse (excluding culverts and ditches) will require a River Condition Assessment undertaken by an accredited River MoRPh surveyor.

Small sites have a separate metric, which must be completed by a competent person.

In cases where priority habitats, irreplaceable habitats, protected sites, and/or European protected species are present on site, or the habitats on site are not listed within the small site metric, then the full metric must be used. For any off-site interventions as part of small site developments, a full metric will need to be used, and land managers will need to complete the off-site tab.

For more information, please visit the DEFRA guidance on statutory biodiversity metric tools.

BNG should ideally be achieved on-site, following the biodiversity gain hierarchy. Off-site BNG should be located as close as possible to the development site to benefit local biodiversity and communities. Further details on the biodiversity gain hierarchy can be found here.

Significant on-site and all off-site BNG land will need to be formally registered on the Natural England Biodiversity Gain Site Register. At present, applicants will need to arrange BNG offsets within their own landholdings or with a third-party, such as landowners and habitat banks. Currently, we  are unable to provide a list of third-party participants or act as a broker. As a last resort, applicants can purchase credits from the statutory biodiversity credit scheme which go towards habitat creation plans across the UK. However, this will need to be approved by us prior to purchase, and applicants will need to justify how they have rigorously followed the BNG principles and rules.

The following information must be submitted with a Major planning application submitted on/after 12th February 2024:

  • A Biodiversity Statement
  • Completed biodiversity metric spreadsheet
  • On-site Biodiversity baseline plan
  • On-site Biodiversity draft proposed plan
  • Off-site Biodiversity gain details, if relevant – baseline and proposed habitats (metric and plans)

The required contents and format of these documents is set out below.

A Biodiversity Statement

To comply with national requirements, the Biodiversity Statement must include the following:

  • whether the applicant believes that planning permission, if granted, would be subject to the biodiversity gain condition;
  • the pre-development biodiversity value of the onsite habitat on the date of application (or an earlier date)
  • where the applicant wishes to use an earlier date, the proposed earlier date and the reasons for proposing that date;
  • the publication date and version of the biodiversity metric used to calculate the pre-development biodiversity value
  • whether the pre-development biodiversity value is affected by degradation (see details in Planning Practice Guidance)*
  • details of any irreplaceable habitat present, if applicable (see Planning Practice Guidance and Irreplaceable Habitats Regulations 2024).

*Note that any habitats damaged or destroyed by unauthorised activities occurring post 30th Jan 2020 will need to be included within the calculations based on their former habitat type and condition and degradation activities in connection with a previous planning permission carried out after 25 August 2023 should also be recorded as the biodiversity value immediately before the carrying out the activities.

In addition to the above, to enable the LPA to determine whether the general biodiversity gain condition is capable of being successfully discharged, and whether a S106 legal agreement is required, the Biodiversity Statement must also include the following (or if desired these details can be submitted in the form of a draft submission of a Biodiversity Gain Plan):

  • the proposed post-development biodiversity value of the onsite habitat
  • details of the project design steps taken to avoid and minimise adverse biodiversity impacts, the approach to enhancing biodiversity on-site including contribution to habitat connectivity with areas beyond the site, and consideration of the restoration and creation of priority habitats in a local context (see ‘Designing for BNG’)
  • details of any proposed off-site biodiversity enhancements, use of local habitat bank and/or use of National Credits scheme (see Biodiversity Units and National Credits sections of guidance)
  • condition assessment sheets used in completion of the biodiversity metric – these should be provided as an Appendix to the Biodiversity Statement, for habitats that require condition assessment (see Defra Biodiversity Metric)

A draft Biodiversity Gain Plan may be submitted at the validation stage to provide information on the strategy on how BNG is to be delivered and secured.

Completed Biodiversity Metric

The Statutory Defra Metric must be used.  The metric should be submitted in its entirety, as an Excel spreadsheet (macros disabled). Do not delete unpopulated tabs, even if they are not relevant to the application.

Information submitted must include:

  • Input tabs of the spreadsheet, including background details, pre-development biodiversity value, details of any irreplaceable habitats present, the draft proposed post-development biodiversity value and any draft off-site biodiversity details if required to achieve target
  • Results tabs of the spreadsheet, including trading summaries, showing no trading errors

The biodiversity metric must be completed by a competent person.

A PDF version must also be submitted, to allow the spreadsheet to be uploaded onto our planning portal.

Biodiversity Site Plans

To comply with national requirements, the following must be submitted:

  • An On-site Biodiversity baseline plan, drawn to an identified scale and with North arrow, showing on-site habitats (in UK Habitat classification) which must align with the biodiversity metric spreadsheet.

In addition to the above, to enable the LPA to determine whether the general biodiversity gain condition is capable of being successfully discharged, the Biodiversity Statement must also include the following:

  • An On-site Biodiversity draft proposed plan drawn to an identified scale and with North arrow, showing on-site habitats proposed, to achieve net gain.

If off-site biodiversity measures are proposed, equivalent details must also be provided i.e. baseline and proposed habitat plans.

The evidence required to demonstrate exemption will depend upon the basis of the exemption. Examples of scenarios of exemptions, are provided in the national BNG Planning Practice Guidance.

If the LPA is satisfied that at least 10% biodiversity net gain is capable of being achieved, the general biodiversity gain condition will be attached to the planning permission. This will require the submission of, and subsequent implementation of, a full Biodiversity Gain Plan.

A finalised Biodiversity Gain Plan, using Defra’s template or equivalent set of information, must be submitted and approved by the LPA, prior to the commencement of development. This must then be implemented in accordance with the General Biodiversity Condition.

Details on Biodiversity Gain Plan covers the following aspects:

  • Submission details e.g. data, planning application number, name of LPA
  • How the biodiversity gain hierarchy has been followed
  • Arrangements for maintenance and monitoring of habitats
  • Completed biodiversity metric calculation tool (as an Appendix)
  • Pre-development and post-development biodiversity values
  • Irreplaceable habitats information including bespoke compensation, if relevant
  • Registered off-site gains allocated to the development
  • Value of the registered off-site gain in relation to the development
  • Purchase biodiversity credits, if relevant
  • Pre- and post-development plans

A Habitat Management and Monitoring Plan, using Defra’s template or equivalent set of information, must be submitted and approved, prior to commencement of development, if the site includes significant on-site habitat enhancements. The definition of significant on-site habitat enhancements will be considered on a case by case basis, in line with the latest guidance.

Significant on-site and off-site BNG must be legally secured for a minimum of 30 years, typically through planning conditions, S106 agreements, and conservation covenants.

For more information, please visit the DEFRA guidance on legal agreements to secure BNG

Information will be provided on our monitoring charging schedule in due course. In addition, a legal agreement template will be available on our website soon, this can be provided upon request to

Applicants are responsible for monitoring BNG progress and submitting reports to us at agreed intervals across the management and monitoring period. Reports should contain relevant data, including biodiversity targets, habitat condition assessments, updated statutory metric, details of progress towards target conditions, changes since last monitoring report, recommendations for changes to the Biodiversity Gain Plan as appropriate, and updated GIS shapefiles where necessary.