Biodiversity Net Gain (BNG)

Local planning application requirements

Biodiversity net gain (BNG) means development must improve biodiversity. Planning permission now requires a biodiversity gain condition, ensuring the project's biodiversity value is at least 10% higher than before. This is mandatory under the Town and Country Planning Act 1990, updated by the Environment Act 2021. View Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021).

The 2024 BNG guidance outlines a priority list called the biodiversity gain hierarchy. It prioritises avoiding harm to habitats, then mitigating impacts by enhancing or creating habitats on-site before using offsite gains or biodiversity credits.

If a planning application falls under the biodiversity gain requirement, it must include the following information. This helps us assess biodiversity net gain (BNG) as part of the planning process.

The application must include a statement confirming whether the applicant believes the development would be subject to the biodiversity gain condition. If not, they must explain why.

For developments claiming an exemption due to minimal impact or self-build/custom-build status, a BNG Statement of Exemption must be submitted. This statement should clearly explain the reason for the exemption and include any supporting details.

Where development is considered to be subject to the biodiversity gain condition, the following information should be provided:

Biodiversity Net Gain Assessment
Completed BNG Metric submitted in Excel form
BNG plan(s) submitted in both PDF and GIS Shapefile format, utilising the relevant version of UKHab methodology and
Completed LBTH BNG checklist.

The BNG assessment

The BNG (Biodiversity Net Gain) Assessment must include:

A statement confirming whether the applicant believes the biodiversity gain condition will apply if planning permission is granted.
The biodiversity value of the site before development, using the relevant biodiversity metric (Statutory Metric or Small Sites Statutory Metric). This must include calculations, the metric’s publication date, and its version.
If using an earlier assessment date, the chosen date and the reason for it.
A statement indicating if the biodiversity value has decreased due to activities on the site (known as "degradation").
If unauthorised degradation happened between 30 January 2020, and the application date, the biodiversity value should be based on the condition of the site before those activities took place.
If authorised activities (with planning permission) reduced biodiversity after 25 August 2023, confirmation of whether the development has started or is still incomplete. The biodiversity value should be based on the condition before those activities began.
A description of any irreplaceable habitat present on the site at the time of application (or an earlier date).
Site plans (before and after development) drawn to scale, showing the site boundary, existing habitats, and any irreplaceable habitats, using the appropriate UKHab methodology.
The biodiversity value after development, including measures to reduce harm to existing habitats and actions taken to achieve biodiversity net gain.

Statutory Metric or Small Sites Statutory Metric

The completed Statutory Metric or Small Sites Statutory Metric, as relevant, should be submitted in Excel form, and should be completed in full including sufficient details, an absence of any major errors (see relevant user guidance).

Where a Small Sites Statutory Metric (SSM) is used, the applicant should confirm the following in the BNG Assessment:

the only habitats available in the SSM are present on-site, this means any site containing any additional habitats such as riparian zones not included in the SSM must use the Statutory Metric,
there are no priority habitats present on-site
there are no statutory protected sites or habitats present and
there are no European protected species present.

For phased developments, the submitted details should demonstrate how the development as a whole will achieve at least 10 per cent net gain.

Further information is also required, but can be provided either at full application stage as a draft, and is to be secured as a condition for post-planning approval if permission is granted. This includes:

a final Biodiversity Gain Plan.
a habitat management and monitoring plan (HMMP), which is mandatory where there are significant onsite or offsite enhancements. This must detail how you will manage habitats, monitor habitats, report on monitoring results, review management proposals, change habitat management to support the intended outcomes. This applies to developments with off-site gains and significant on-site habitat enhancements. Examples of this include developments providing medium or higher distinctiveness habitats, and full description of what is considered significant onsite enhancements is provided separately.
if your site is exempt from providing a HMMP and legal agreement, details on how the proposed landscaping will be managed and maintained should still be provided.

A legal agreement will also be required, which will be produced by LBTH. This should set out how the habitat(s) will be maintained, responsibilities for creation or enhancement works, and responsibilities for maintenance management and monitoring for at least 30 years. This also only applies to developments with off-site gains and significant on-site habitat enhancements.

Where applicants consider that the development would not be subject to the biodiversity gain condition, Article 7 of The Town and Country Planning (Development Management Procedure) (England) Order 2015 provides that the applicant must provide a statement as part of the planning application setting out the reasons why they believe this is the case.

When required

This requirement applies to major schemes from 12 February 2024 and minor schemes from 2 April 2024. If a planning application for a development was made before day one of mandatory BNG on 12 February 2024 for major schemes or 2 April 2024 for minor schemes, the development is exempt from BNG.

There will be developments which would be exempt from BNG, exemptions include:

variations of planning permissions decided made before day one of mandatory BNG on 12 February 2024 for major schemes or 2 April 2024 for minor schemes
retrospective planning permission made under section 73A of the Town and Country Planning Act 1990 (as amended)
development with no impact on priority habitat and where impacts fall below the specified 'de minimis' threshold, including less than 25m² of habitat with value greater than zero, or 5m long for linear habitats such as hedgerows and rivers
householder applications
off-site gain developments, where habitats are being enhanced for wildlife and
certain self-build and custom build developments, under nine dwellings and on a site no larger than 0.5 hectares.

Policy / drivers

BNG is mandatory under Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021).