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Biodiversity Net Gain (BNG)

Biodiversity net gain (BNG) is an approach to development that leaves nature in measurably better condition by creating and enhancing habitats.

Delivering BNG is mandatory for major and minor development sites, with some exemptions. For sites subject to mandatory BNG, planning permission will include a pre-commencement biodiversity gain condition, ensuring the project's biodiversity value is at least 10% higher than before.

Find out more about BNG for developers.

It is important to note that the mandatory requirement for BNG does not change existing requirements and protections for the natural environment, such as protecting designated nature conservation sites and important habitats and species. Developments must still respond to biodiversity policy in the Tower Hamlets Local Plan.

What to submit with your planning application

Where development is subject to the biodiversity gain condition, the following information should be provided:

  1. Biodiversity Net Gain Assessment – details of what is required can be found in the LBTH BNG Checklist
  2. Completed BNG Metric submitted in Excel form
  3. BNG plan(s) submitted in both PDF and GIS Shapefile format, utilising the relevant version of UKHab methodology and
  4. Completed LBTH BNG checklist.

For developments claiming an exemption, a BNG Statement of Exemption must be submitted. This statement should clearly explain the reason for the exemption and include any supporting details.

Exemption from BNG

An application must include a statement confirming whether the applicant believes the development would be subject to the biodiversity gain condition. If not, they must clearly explain the reason for the exemption and include any supporting details.

Developments exempt from BNG as of 6 August 2026:

  • Sites under 0.2ha (where priority habitat is not impacted)
  • Temporary development for land to be reinstated within 5 years (where priority habitat is not impacted)
  • Sites where less than 25m2 of non-priority habitat, or less than 5m of linear habitat (hedgerows or watercourses) within the red line boundary are impacted (de minimis exemption)
  • Self- or custom build developments submitted prior to August 6 2026.

View more information about priority habitats.

View more information about what type of developments are exempt from BNG.

Delivering BNG in development

Delivery of BNG must follow the ‘biodiversity gain hierarchy’. You can combine all 3 steps but must follow the steps in order:

  1. In the first instance you should retain and protect areas of high biodiversity value and avoid or reduce negative impacts on biodiversity. BNG should be delivered on site as far as possible.
    1. You must not undertake pre-emptive site clearance to reduce the biodiversity value of your site prior to the granting of planning application.
  2. If reaching 10% net gain is not possible on site, BNG can be delivered off-site, or in a combination of on- and off-site gains. Developers can either make off-site biodiversity gains on their own land outside the development site, or buy off-site biodiversity units (i.e. from a habitat bank)
    1. Any off-site biodiversity units must be secured by a legal agreement. View more information about delivering BNG offsite
  3. If it is not possible to achieve the target net gain via on- or off-site BNG, a developer must purchase statutory biodiversity credits from the government.

For developments subject to mandatory BNG and granted planning permission, the following will be required

  • A final Biodiversity Gain Plan
  • For sites with significant onsite gains or offsite gains, a habitat management and monitoring plan (HMMP). This must detail how you will manage and monitor habitats, report on monitoring results, review management proposals, change habitat management to support the intended outcomes.
  • If an a HMMP is not required, details on how the proposed landscaping will be managed and maintained should still be provided.
  • For phased developments, details of how BNG will be delivered in each phase.

Significant on site gains

Significant onsite gains are areas of habitat enhancement which contribute significantly to your development’s BNG relative to the biodiversity value before development.

What counts as significant depends on the existing habitats within your development site and the scale of development you are proposing.

Examples of significant onsite gains include (but are not limited to):

  • Retained habitats which are being enhanced
  • Significant new tree planting
  • Extensive (biodiverse) green roofs
  • New native woodlands and mixed native scrub, orchards and hedgerows
  • Wildflower meadows and areas of biodiverse grassland
  • New ponds, wetlands and SuDS (such as swales, ditches and rain gardens)
  • Improvements in and around watercourses (i.e. riparian zone enhancement)

Significant onsite gains and any offsite gains must be maintained for a minimum of 30 years so that they achieve the stated target habitat condition. They must be legally secured by planning condition, section 106 agreement or conservation covenant. More information about legal agreements for BNG.

Monitoring fees

The council must ensure that the relevant monitoring for significant biodiversity gains takes place at the correct times and that all monitoring reports are fully reviewed, assisting landowners and developers to deliver the planned enhancements to biodiversity.

Monitoring costs will be required to cover the time taken to oversee monitoring of significant on-site enhancements, and shall be secured via s106 agreements.

Monitoring fees will be agreed on a case-by-case basis, and will vary depending on site size, difficulty of habitat type creation and accessibility of a site for assessment.

Policy

BNG is mandatory under Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021).