Biodiversity Net Gain, guidance for developers and ecological consultants

Commencement dates

BNG becomes mandatory for applications for major development made on or after 12 February 2024 and for applications for minor development (small sites) made on or after 2 April 2024. 

A small site means:  

• residential development where the number of dwellings is between one and nine, or if this is unknown, the site area is less than 0.5 hectares 
• commercial development where floor space created is less than 1,000 square metres or total site area is less than one hectare

Exemptions

The following types of development are exempt from the BNG requirement (opens new window):

• Householder development.
• Permitted development.
• Development subject to the de minimis exemption - defined as development that does not impact a priority habitat and impacts less than: 
  • 25m2 (5m by 5m) of habitat
  • 5m of linear habitat such as hedgerows. 
• Self-build and custom build development when all the following conditions apply:
  • it consists of no more than nine dwellings
  • it's on a site which has an area no larger than 0.5ha 
  • it consists exclusively of dwellings which are self-build or custom housebuilding as defined in section 1(A1) of the Self-build and Custom Housebuilding Act 2015. (opens new window)
• Development of a biodiversity net gain site, where that requires planning permission.

Variations and reserved matters are exempt from mandatory net gain if the original or outline application was made prior to the relevant commencement date above.