Biodiversity Net Gain (BNG)

Biodiversity net gain (BNG) is a way of creating and improving natural habitats. BNG makes sure development has a measurably positive impact ('net gain') on biodiversity, compared to what was there before development. It does this by requiring developers to increase biodiversity by a minimum of 10%.

It is in addition to existing legislation for protected habitats and species, but is also a mandatory requirement in the Environment Act 2021.


DEFRA has published a biodiversity metric tool, which uses biodiversity units to measure the value of a habitat. It calculates units based on the size, distinctiveness, condition and strategic significance of the habitat.

You can then use these units as credits to off-set biodiversity loss your development may cause.

You can gain units either on-site or off-site. You can gain on-site units by improving the habitat on-site via landscaping and green infrastructure. If you are unable to improve biodiversity directly on-site, you can do it on other land you already own, or in partnership with public or private landowners, to gain off-site units.

If you cannot gain on-site or off-site units, you need to buy statutory biodiversity credits from the government. This must be a last resort. The government will use the revenue to invest in habitat creation in England.  

How this will affect your planning application

The following application types are in scope and will require further information:

  • Major developments and Priority Habitat Sites from 12 February 2024*
  • Minor development sites from 2 April 2024**
  • Nationally Significant Infrastructure Projects (NSIPs) from November 2025

*Major Definitions

Major development is defined as:

Residential development

  1. Where the number of dwellings being proposed is ten (10) or more
  2. If the specific number of dwellings to be provided is not known, a site area exceeding 0.5 hectares.

Non-residential development

  1. The provision of a building or buildings where the allocated floor space being created as a result of the development is 1,000 square metres or more
  2. Where the development has an area of 1 hectare or more
  3. Change of use applications over 1,000 square metres or more
  4. All full applications concerning mineral extraction and waste development.

**Minor Definitions

Minor development is defined as:

Residential development

  1. Development where the number of dwellings proposed is between one and nine inclusive on a site and has an area of less than one hectare
  2. If the number of dwellings is unknown, then the site area must be less than 0.5 hectares.

Non-residential development

  1. Development defined as less than 1,000 square metres of proposed floor space
  2. Sites smaller than one hectare

The following application types are out of scope and are exempt:

  • Specific applications including retrospective application made under Section 73A, Section 73 Permissions (where the original permission was either granted before 12 February 2024 or the original permission was made before 12 February 2024), Permission in principle (not including the technical details consent) and the approval of reserved matters for outline planning permission.
  • Permitted development
  • Other planning routes including local development orders, simplified planning zones, neighbourhood development orders, successful enforcement appeals and deemed planning permissions.
  • A householder application
  • A development impacting habitat of an area below a threshold of 25m2, or 5m for linear habitats (De Minimis)
  • A biodiversity gain site
  • A small scale self-build and custom housebuilding

How we will secure BNG

We will normally use planning conditions to secure on-site habitat enhancements. You will need to secure and maintain the enhancements for at least 30 years. Other potential conditions could include monitoring and reporting arrangements.

We are likely to use a legal agreement (such as a Section 106 agreement) to secure any off-site enhancements, including their management and monitoring.

What you need to submit

All developers must submit a:

  • Biodiversity Net Gain Statement
  • Site plan, drawn to an identified scale marked with the direction of north, showing on-site habitat existing on the date of application (or an earlier date), including any irreplaceable habitat
  • Completed biodiversity metric (as an Excel-file type), for both pre-development and post-development
  • A draft BNG plan

You have to submit final a Biodiversity Gain Plan, which we must approve, before you start work. You need to provide us with a draft version of the plan with your application.

You also need to submit a Habitat Management and Monitoring Plan (HMMP), to show how you will manage and monitor the biodiversity enhancements for at least 30 years.

You can download a:

which you need to complete and submit as part of your application.

You must submit both plans through the Discharge of Conditions application process.

Further information

You can find more details about BNG on GOV.UK.


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