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Biodiversity Net Gain

Biodiversity Net Gain (BNG) is an approach to development and land management that leaves biodiversity in a measurably better state than before, after first avoiding and minimising harm.

Current planning policy encourages developments to provide a BNG but prohibits net losses.

We have a Biodiversity Action Plan (BAP). This document sets out the highest priorities for action to conserve Northamptonshire's most threatened and declining habitats and species.

We will work with developers to pursue BNG when assessing planning proposals. Sometimes it is not possible to develop land and avoid a net loss. Where residual losses of biodiversity are unavoidable, developers can arrange for the creation habitat of equal or greater value to wildlife. This is called ‘biodiversity offsetting’.

Biodiversity offsetting is a form of compensation, the final step in the mitigation hierarchy. Biodiversity offsetting may not be suitable in all instances, particularly when proposals impact designated sites, irreplaceable habitats or priority habitats. Biodiversity offsetting is provided at our discretion following a comprehensive review of the proposed development.

Mandatory Biodiversity Net Gain

Government has set out next steps on plans for new housing, commercial and infrastructure developments to be “nature positive” by confirming that upcoming legislation to bring in these rules will be laid in November.

Under the updated timetable developers in England will be required to deliver 10% “Biodiversity Net Gain” from January 2024 onwards for new housing, industrial or commercial developments. Biodiversity Net Gain for small sites will be applicable from April 2024, and implementation for Nationally Significant Infrastructure Projects remains planned for 2025.

By the end of November the Department for Environment, Food and Rural Affairs (DEFRA) will publish all guidance and the regulations Mandatory Biodiversity Net Gain will only apply to new applications for planning permission for major development made after November 2023. More information can be found on the Gov.UK website.

When BNG information will need to be supplied

All major and minor developments will need to submit Biodiversity Gain Information. This includes the following categories of applications

  • Full planning application
  • Full planning application (with listed building consent)
  • Full planning application (with demolition in a conservation area)
  • Full planning with advertisement consent
  • Outline application with some matters reserved
  • Outline application with all matters reserved
  • Reserved matters application

A final Biodiversity Gain Plan (BGP) must be submitted and approved by us prior to commencement of the development.

All planning projects subject to BNG requirements should consider biodiversity from the very outset, prior to site design, and ideally at site selection stage. This should help minimise the need for providing replacement habitats.


Householder applications, changes of use, and permitted development are exempt from formal BNG mandatory requirements.

What the Biodiversity Gain information should include

We will expect Biodiversity Gain Information to include a report, completed metric spreadsheet and GIS imagery. This may include further information towards a complete Biodiversity Gain Plan should such information be available.

The Biodiversity Gain information must cover the following:

  • The pre-development biodiversity value of the site as calculated using the relevant Defra metric (provided in Excel format). The main metric should be assessed using the Defra condition sheets. Any habitats damaged or destroyed post 30 January 2020 will need to be included within the calculations based on their former condition
  • The project design steps taken to avoid and minimise adverse biodiversity impacts (provided in text document)
  • The proposed approach to enhancing biodiversity on-site (provided in text document)
  • Any proposed off-site biodiversity enhancements (including the use of credits) that have been planned or arranged for the development (provided in text document)
  • A working assessment of the expected Biodiversity Net Gain (provided in text document)
  • The completed metric spreadsheets used to calculate the pre-development biodiversity value and to approximate the post-development value (provided in Excel format)
  • Habitat condition sheet assessment with justifications (provided in text document)
  • Maps of baseline habitats, an annotated Ecological Mitigation Map, and illustrative post-development habitat proposals including retained and proposed new features (required as a separate document with imagery produced using GIS software)

BNG practice is still in development, so the guidance provided here is likely to evolve. Please check this page for updates, directly before submitting your planning application.

Natural England have produced a Green Infrastructure Planning and Design Guide which provides practical, evidence-based advice for good quality green infrastructure, including how to:

  • plan
  • design
  • deliver
  • manage

This approach to development incentivises the avoidance of damage and loss of highly valued habitats and aims to result in the creation and improvement of habitats in locations which will deliver the best outcomes for biodiversity.

If you have any queries you can contact the ecology team by email at [email protected].

Last updated 18 December 2023