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Biodiversity Net Gain

Information about Biodiversity Net Gain and its impact on planning applications

Biodiversity net gain (BNG) aims to leave the natural environment in a better state than it was, which is measurable. The statutory framework for biodiversity net gain has been designed to ensure that the biodiversity gain objective of achieving at least a 10% gain in biodiversity value will be met for development granted planning permission.

BNG became mandatory on 12 February 2024 for Major developments.  It is mandatory for small sites from 2 April 2024 and for nationally significant infrastructure projects from 25 November 2025.

How biodiversity net gain is applied through the planning process

It is important that biodiversity net gain is considered throughout the planning process.  

Additional information needs to be submitted at the application stage, and when granted, to discharge the biodiversity net gain condition. This is known as the biodiversity net gain plan stage. 

This is to ensure that the biodiversity gain objective is met. 

Applications in scope for Biodiversity net gain

Major developments:

  • Residential development comprising of 10 or more dwellings or where site is >0.5ha
  • Non-residential buildings where floor space is >1000sqm of site is >1ha
  • Working with minerals and waste developments

Small sites:

  • Residential developments comprising 1-9 dwellings on a site <1 ha or a site <0.5ha where the number of dwellings is unknown
  • Non-residential buildings where floor space is <1000smq or site is <1 ha

Application for Biodiversity net gain

To apply, you must complete:

If this information has not been provided, the Council will refuse to validate the application. Within the planning application form applicants will be asked to confirm whether this information accompanies the application. Where these details have been provided elsewhere in accompanying documents, applicants are encouraged to refer to these rather than duplicate this information within the application form.

The section below explains the types of application that are exempt from biodiversity net gain. 

Applications exempt from biodiversity net gain

Applications exempt from BNG as from 2 April 2024:

  • Householder
  • Self-build and custom build
    • Which consists of no more than 9 dwellings and is carried out on a site which has an area no larger than 0.5 hectares
  • Section 73A Variation/removal of condition
    • Retrospective planning permissions made under section 73A (VOCS)
  • Section 73 Variation/removal of condition
    • Section 73 permissions where the original permission which the section 73 relates to was either granted before 12 February 2024 or the application for the original permission was made before 12 February 2024. Post 12 February 2024 it would have been provided with the original permission so not required
    • Note: A BNG condition cannot be removed or varied. May require a BNG plan if the S73 application affects the post development biodiversity value
  • Permission in principle
    • Note: Tech details would not be exempt
  • Reserved matters
  • Development of a biodiversity gain site
    • Development which is solely or mainly for the purpose of fulfilling, in whole or part, the biodiversity net gain conditions which applies to another development
  • Urgent Crown development
  • Development related to high speed railway transport network
  • Development order under Section 59
  • Development subject to the de minimis exemption
    • The development must not impact on any onsite priority habitat. If there is an impact on other onsite habitat, that impact must be on less than 25 sqm (i.e. less than 5 x 5 metre square).
    • An applicant must state if they are applying this exemption on the application form and provide reasons for this. The exemption is designed to cover planning permissions for:
      • Development which only impacts on onsite habitat with a biodiversity value of zero so no gain would be required if there was no exemption;
      • Developments where there is only a de minimis impact on other onsite habitat to ensure biodiversity net gain is applied proportionally;
      • Minor development in established areas of habitat where the development would have less than 25 square metres (or less than 5 metres for linear habitat) impact on this habitat (unless priority habitat); and
      • Change of uses to development where there is no or only a de minimis impact on onsite habitat.

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