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BNG: what’s happened and what’s coming next

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Aerial landscape view of homes on an English housing estate - Getty

Here in the Defra Biodiversity Net Gain (BNG) team, we’ve likened BNG to a baby elephant! It’s big, complex and needs a herd to nurture it to adulthood. Feeding into the Environmental Improvement Plan’s nature recovery targets, BNG gives the development industry an opportunity to work with the planning system to make sure development improves and protects our precious biodiversity, rather than further eroding it. It also has the potential to boost green jobs, innovation in habitat mapping and make green space more accessible to the public.

When is BNG happening?

Following our consultation on BNG implementations and regulation, we made the decision to phase BNG’s introduction , starting with most major developments from January 2024. More time will be given to small sites (April 2024, see definition in the consultation response) and nationally significant infrastructure projects (NSIPs) (expected in 2025). This will allow developers, landowners and local planning authorities more time to familiarise themselves with the requirements and learn lessons from early practitioners.

Mandatory BNG will only apply to new applications for planning permission for major development made after January 2024. We are working with DLUHC on transitional arrangements to ensure that BNG is not applied retrospectively to planning applications that have been submitted or have already been granted permission before the implementation date. For example, applications made under s73 where the earlier permission was submitted or granted before this date. We will set out more detail on these arrangements in due course.

What’s been the journey so far in 2023?


What’s the difference between biodiversity units and credits?

In BNG, there is a key difference between biodiversity units and credits:

  • Biodiversity units refers to the output of the biodiversity metric. It’s also the term used for the sale of off-site biodiversity units – i.e. ‘1 unit of modified grassland costs £xx’.
  • Statutory credits are the last resort option for developers provided by Government, if the site’s BNG cannot be delivered onsite or via purchasing off-site biodiversity units.

What can you expect before BNG becomes mandatory?

Secondary Legislation

Following on from our consultation response, we’re drafting the following statutory instruments:

  • Exemptions: which types of developments will be exempt from mandatory BNG.
  • Irreplaceable Habitats: which habitats should be considered as irreplaceable for BNG purposes and therefore subject to bespoke compensation
  • The Register: how the register will work and what will be mandated (including the need for land managers to register off-site biodiversity units).
  • Planning System: how BNG will work through the planning process, including approval of the biodiversity gain plan and the process for phased development.
  • Commencement regulations: Switching on the provisions in the Environment Act 2021 for the implementation date and setting out transitional arrangements for certain routes to planning permission.

We'll be providing further information on these ahead of BNG becoming mandatory.

Case studies

We’re planning on publishing on and off-site examples of BNG on this blog, to help bring BNG to life and aid best practice: make sure to sign up to the Land Use Blog alerts to receive notifications of these!

Written guidance

All guidance will be published on this page on a rolling basis. We are working on the below guidance; this list is not exhaustive and further topics may be added:

Habitat management and monitoring plan 

Biodiversity net gain plan

Meeting a development's total biodiversity net gain (onsite and offsite) 

Securing biodiversity gain sites 

Metric updates 

Biodiversity gain sites register 

30+ years 

Statutory credits 

Phased development

Irreplaceable habitats


Redline boundary

Baseline and degradation of habitats



Small sites, small sites metric


Responsible bodies

Prospective responsible bodies will need to apply to Defra to be designated: the designation process is now open. We will publish guidance on applying to become a responsible body when the application process is launched. Official designations will be made 12 weeks after the designation process has closed.

Habitat Management Monitoring Plan (HMMP) templates

Natural England will make HMMP templates available before BNG becomes mandatory. These will be suggested for land managers and their responsible bodies/local planning authorities to use.

Digital tools

The credit sales service and the biodiversity register will launch when BNG becomes mandatory.



Sharing and comments

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  1. Comment by simon Lamb posted on

    I can't see what the implications of offsite BNG for cattle grazing will be anywhere. Will summer and or winter grazing be allowed? If so to what degree?

    • Replies to simon Lamb>

      Comment by Anna posted on

      Hi Simon,
      Thanks for your question: light grazing is allowed (and can work well) for the management of certain habitat types in BNG, including some grassland and heathland. We'd recommend speaking to an ecologist on the specific habitat types that this would be a good option for and to determine the appropriate grazing intensity.
      Hope this helps,
      Anna - BNG landowner engagement


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