Biodiversity Net Gain Exemptions 


A guide to the types of development that will be exempt from the mandatory biodiversity net gain (BNG) requirements.

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Biodiversity Net Gain

What are the Biodiversity Net Gain Exemptions ?

Incorporation into the planning process has intertwined biodiversity gain requirements with conservation covenants, local lists, plans, national validation requirements, nationally significant infrastructure projects, protected species, Sites of Special Scientific Interest (SSSI), statutory protected sites, and other relevant policies under the UK government's legal framework. Overlaps are evident where existing local policies are applicable, such as the Wildlife and Countryside Act 1981, the Town and Country Planning Act 1990, and the Conservation of Habitats and Species Regulations 2017.


Developments subject to biodiversity net gain regulations must have a BNG plan and report. Otherwise, issues affecting rural communities, like existing conservation covenants or protected species surveys, must be resolved before the local council considers granting planning permission. While it is advantageous to avoid the BNG planning condition, determining whether your project is subject to these regulations is essential.

BNG Exemptions Examples

  • Alternative Planning Applications


    • Planning decisions are closely linked with biodiversity net gain, relying on assurances that legal requirements will be successfully met. The additional details provided through biodiversity gain plans serve as the foundation for the proposed method of achieving mandatory BNG.
    • While the results of traditional planning condition applications may differ based on the biodiversity net gain plan and report, alternative applications, certain permissions, and other specific stipulations might render adherence to BNG unnecessary. For example, the policy does not apply to several other planning acceptance routes, such as old mineral permissions, permitted development rights, pre-commencement condition agreements, simplified planning zones, subsequent technical details consent, successful enforcement appeals, transitional arrangements, and any actions to secure planning permission through a development order, including local development orders and neighbourhood development orders.

  • Biodiversity Gain Sites


    • The optimal result for any development subject to mandatory requirements is to achieve a 10% on-site biodiversity net gain. If the mitigation hierarchy fails to initiate sufficient habitat creation and enhancement to surpass the desired threshold, sourcing off-site biodiversity gains becomes a fallback strategy to attain or exceed a 10% net gain for BNG.
    • To facilitate off-site provisions, numerous biodiversity net gain sites nationwide have been established to produce these off-site gains. When space is available, our team member will review a biodiversity gain site register to identify an appropriate land parcel. Subsequently, statutory biodiversity credits are purchased as off-site biodiversity units from landowners, matching the quantity needed to fulfil the increase within the site's red-line boundary.
    • When biodiversity gain sites are designed to cultivate statutory credits, their advantages compensate for any biodiversity value deficits, thus exempting them from off-site BNG regulations.

  • Custom Build and Self-Build Developments

    • Certain circumstances allow for an exemption to self-build or custom housebuilding as outlined in Section 1 of the Self-Build and Custom Housebuilding Act 2015. Exemptions are granted for small-scale self-build or custom-build projects that include nine or fewer dwellings on a site no larger than 0.5 hectares, provided the development solely comprises dwellings that are custom-built or self-built, adhering to the principles of self or custom-build development.

  • De Minimis Exemptions


    • In minor developments, the de minimis exemption precludes the BNG objective if the non-major development plans are likely to cause only minimal harm to irreplaceable habitats. Specifically, the de minimis threshold is applicable if the developer affects less than 25 square meters of the on-site habitat with a biodiversity value above zero, unless it is a priority habitat, such as modified grassland, or impacts less than five meters of on-site linear habitats like hedgerows and watercourses.
    • Any loss or degradation of habitat that leads to a decrease in the site’s biodiversity value will affect the development's impact on the natural environment. Degradation of habitat during development can happen if there is a change in the condition or type of habitat, resulting in a negative unit score. This issue becomes more critical when it involves an irreplaceable habitat, but cumulative harm to multiple linear habitats could also impede minor applications, even if it stems from hedgerow units or watercourse units.


  • Homeowner Applications


    • Minor development projects like home extensions, loft conversions, or conservatory construction are exempt from the biodiversity net gain requirement. The application form for householder applications clearly states that such developments are not subject to mandatory BNG regulations.
    • However, it's crucial to distinguish between small homeowner-managed developments and minor residential or non-residential developments on a small site. A specific metric for small sites has been established, and starting from 2 April 2024, developers must apply it to any project considered a minor development. For instance, in residential projects, a small site is defined as having 1 to 9 dwellings on an area less than one hectare, or, if the dwelling count is unspecified, a site no larger than 0.5 hectares. In contrast, a small non-residential development is characterized by proposed floor space under 1,000 square metres and a site area under one hectare.

  • Ongoing Planning Applications

    • While it may soon be a moot point given the time elapsed since the universal implementation, planning applications submitted before the BNG requirements commenced on 12 February 2024 are not subject to the policy's conditions. However, if the application was not approved before this date, the local council may have already mandated compliance. During the transition period, local authorities nationwide had the discretion to require adherence to the policy, which could be especially relevant if the application pertains to reserved matters.

  • Rail Transport Networks


    • According to Section 1 of the High-Speed Rail (Preparation) Act 2013, developments that are part of, or ancillary to, a high-speed railway transport network are automatically classified as exempt. This includes developments that establish rail connections between Birmingham, the East Midlands, Leeds, London, Manchester, and Sheffield, as well as parts of the transport network extending to airports, cycleways, footpaths, light railways, and roads deemed pertinent by the Secretary of State.

  • Urgent Crown Developments


    • Section 293 of the Town and Country Planning Act 1990 safeguards Crown land by imposing protective measures against potentially damaging development acti
    • While certain planning policies like biodiversity net gain may be bypassed, urgent Crown developments must still adhere to restrictions as any other public development would. This means the Crown is required to seek planning permission, hazardous substances consent, listed building consent, Tree Preservation Order consent, and consent for demolition within a conservation area from the local authority.
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