Biodiversity net gain: exempt developments

The developments listed in this guide are exempt from BNG rules.

Existing planning applications 

If a planning application for a development’s planning permission was made before day one of mandatory BNG on 12 February 2024, the development is exempt from BNG.

Variations of planning permission

Transitional arrangements also apply for variations to existing planning permissions. There is more information in the planning practice guidance.

Small sitesdevelopments (exempt until 2 April 2024)

A small sitedevelopment does not fall into the category of a major development, as defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.

A small sitedevelopment means:  could include a:  

• residential development where the number of dwellings is between 1 and 9,9 on a site of an area 1 hectare or less, or if thisthe number of dwellings is unknown, the site area is less than 0.5 hectares hectares
• commercial development where floor space created is less than 1,000 square metres or total site area is less than 1 hectare 
• development that is not the winning and working of minerals or the use of land for mineral-working deposits 
• development that is not waste development

Developments below the threshold

A development that’s below the threshold means that it does not impact a priority habitat and impacts less than: than:   

• 25 square metres (5m by 5m) of habitat on-site habitat   
• 5 metres of on-site linear habitats such as hedgerows

A development ‘impacts’ a habitat if it decreases the biodiversity value.   

Find out more about this exemption.

Householder applications

These are applications made by householders as defined within article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.

It includes, for example, small projects like home extensions, conservatories or loft conversions

Self-build and custom build applications

An exemption applies to this type of development when it meets all the following conditions apply:   conditions:   

• it consists of no more than 9 dwellings 
• it’s on a site that has an area no larger than 0.5 hectares    
• it consists exclusively of dwellings that are self-build or custom housebuilding as defined in section 1(A1) of the Self-build and Custom Housebuilding Act 2015

Biodiversity gain site

Developments undertaken mainly for the purpose of fulfilling the BNG planning condition for another development are exempt.

High speed rail transport network

An exemption applies to any development forming part of, or ancillary to, the high-speed railway transport network, comprising connections between all or any of the places or parts of the transport network specified in section 1(2) of the High Speed Rail (Preparation) Act 2013

Other exemptions

The following are exempt by the Environment Act 2021:

• urgent crown developments 
• developments that are granted planning permission by a development order (including permitted development rights)

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