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  • Gail Collins

Biodiversity Net Gain Launch Date Revealed

The Government has revealed the long-awaited commencement date for mandatory biodiversity net gain (BNG) for both major and smaller developments.

The BNG policy, introduced by the 2021 Environment Act, will require developers to demonstrate how they plan to achieve a minimum 10% increase in biodiversity with all new developments in order to obtain planning permission.


From 12th February 2024, BNG will be mandatory for new planning applications for major development made under the Town and Country Planning Act (TCPA) 1990, subject to the confirmed exemptions. Major development includes residential developments with 10 or more dwellings, or where the site area is greater than 0.5 hectares. BNG will apply to new applications for planning permission, except for applications for retrospective permission, the exemptions and transitional arrangements.


BNG for small sites will have an extended transition period and will apply from 2nd April 2024. Small site development includes:


  • Residential development where the number of dwellings is between 1 and 9, or if unknown the site area is less than 0.5 hectares

  • Commercial development where floor space created is less than 1,000 square metres or the total site area is less than 1 hectare

Applications for development will not be deemed valid after the respective dates unless supported by the relevant information contained within the following guidance:


Transitional arrangements are also in place to ensure that BNG does not apply to a planning permission if the application was made before 12th February. It is understood that these transitional arrangements mean that if you received planning permission before 12th February (and that permission wasn’t subject to BNG), if you then apply via the planning permission via Section 73 of the TCPA 1990 to vary a planning condition on that permission, the new permission granted (under section 73) would also be exempt from BNG.


Further guidance on BNG can be found at the following web-link:





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