Biodiversity Net Gain (BNG)

Biodiversity net gain (BNG) is an approach to development to make sure that biodiversity is left in a measurably better state than before development. It encourages development to deliver biodiversity improvements through habitat creation or enhancement and avoiding and mitigating harm.

In England, Biodiversity Net Gain is legislated to become mandatory under Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021) for all planning applications, unless otherwise exempt from the following dates:

  • Major development: 12 February 2024
  • Small scale development: 2 April 2024
  • Nationally Significant Infrastructure Projects (NSIP): November 2025

Developers must assess the pre and post-development habitat value of their proposals to establish that a minimum 10% gain can be achieved prior to submitting a planning application. The delivery of BNG either on-site, off-site or using a new statutory national biodiversity credits scheme will be monitored and enforced over a 30-year period.

Mansfield District Council has produced a guidance note to provide applicants with details of when onsite enhancement of biodiversity will be considered as ‘significant’. It also sets out the circumstances which enhancements will be secured via a condition or a S106 agreement.

Mansfield District Council also has a BNG Supplementary Planning Document (SPD) which sets out the preferred approach to providing BNG from new development in Mansfield District. The SPD can be found at

Further information can be found through Government guidance which is reviewed and updated regularly.