Guide Biodiversity Net Gain

3. Biodiversity Net Gain Requirements for Development Proposals

What information do you need to submit for Validation?

There are new national mandatory validation requirements that must be submitted to allow the LPA to validate the application.

1. The Planning Portal forms have been updated to include the requirement to submit the following information for relevant applications:

• • A statement with written confirmation that mandatory Biodiversity Net Gain does or does not apply

• • The baseline biodiversity value of the onsite habitats, on the date of application (or an earlier date)

• • Where the applicant wishes to use an earlier date, they must detail the proposed earlier date and the reasons for proposing that date

• • The publication date and version of the biodiversity metric used to calculate the baseline value. The publication date of the Statutory Metric is 29/11/2023 and mandatory BNG became a legal requirement as of 12/02/2024. Either date is acceptable. For clarity:

• • • Version of the Metric = Statutory Biodiversity Metric or Small Sites Metric
    • Publication date = 29/11/2023 OR 12/02/2024 (this applies for both metric types as above)

• • Whether any habitat degradation has taken place before the Biodiversity Metric calculations were carried out

• • A description of any irreplaceable habitat(s) on the land the application relates

2. The Statutory Biodiversity Metric/Small Sites Metric* with:

• • Date of Metric completion on the Start Page

• • Baseline calculations fully completed

• • Name of competent person who completed the Metric (to also include the name of the Watercourse accredited person, if different)

* Note, we can only accept these in excel format (.xls) with macros enabled

3. A Map showing:

• • All onsite habitats existing on the date the baseline biodiversity value was calculated, using UK Habitat Classification, including any irreplaceable habitat (s)
  • All onsite habitat parcels should be labelled with a reference number that matches the reference number within the Metric

• • An identified scale and direction of North

• • This can be submitted as a separate document, or it may be included within the ecological report

If this information has not been provided, the local planning authority is unable to validate the application.

What information do you need to submit before Determination?

BNG is a material consideration when determining applications and BNG Planning Practice Guidance (Para 013-015) make it clear that the LPA needs to understand how the BNG requirement is to be met prior to determining the application, so that necessary planning conditions can be imposed and/or planning obligation (S.106 Agreements) signed. 

The following information can be submitted after validation, but is recommended to be included with the initial planning submission to allow for a timely consideration before determination:

1. Written information to include the following – this could be in the form of a draft Biodiversity Gain Plan:

• • The proposed methods of delivery of the biodiversity gain objective including onsite gains, offsite gains and the use of statutory biodiversity credits
  • How the biodiversity gain hierarchy has been considered and adhered to
  • Information about any potential planning obligations required to deliver the biodiversity gain objective connected to the planning application (e.g. should a 106 agreement be required to secure significant areas of onsite habitat)

2. The Statutory Biodiversity Metric/Small Sites Metric with:

• • Completed sections for onsite pre-development and post-development calculations
  • Condition Assessment forms for each habit parcel surveyed, undertaken at an appropriate time of year.
  • Where detailed plans are not available, you should use a default 70:30 ratio of ‘urban – developed land; sealed surface’ to ‘urban – vegetated garden’ when assessing habitats within areas outlined for housing.
  • Evidence for metric decisions should be provided and signposted within the ‘User comments’ column of the metric calculation tool

3. An accurate, scaled map(s) showing:

• • Where pre-development and post-development biodiversity units will occur onsite showing both UK Habitat Classification parcels and corresponding numbers of biodiversity units
  • Where significant onsite enhancement is proposed and labelled to confirm a Habitat Management and Monitoring Plan will apply to this area
  • Any habitats to be retained or enhanced and labelled to confirm a Construction Environmental Management Plan will apply to this area
  • Any offsite parcels of land proposed to deliver biodiversity units with baseline and post-development UK Habitat Classification parcels and corresponding numbers of biodiversity units

What information will be required prior to Commencement?

The statutory framework for biodiversity net gain involves the discharge of the general biodiversity gain condition following the grant of planning permission to ensure the objective of at least 10% net gain will be met for a development. The determination of the Biodiversity Gain Plan (BGP) is the mechanism to confirm whether the development meets the biodiversity gain objective.  Development may not commence until the Biodiversity Gain Plan is approved.

Biodiversity Gain Plan

The Biodiversity Gain Plan sets out how the biodiversity gain objective of at least a 10% gain will be met for the development granted planning permission. It must contain the relevant information to enable the planning authority to determine whether the biodiversity gain objective has been met.

This must be submitted no earlier than one day after permission has been granted and must be approved by East Devon District Council to discharge the general biodiversity gain condition. For ease of use and to ensure all relevant information is submitted, the applicant is encouraged to use the Biodiversity Gain Plan template.

It is recommended that a draft Biodiversity Gain Plan is submitted with planning submission to ensure they have been considered at an early stage and to minimise potential delays with discharging the general biodiversity gain condition.

Habitat Management and Monitoring Pan

A Habitat Management and Monitoring Plan (HMMP) should be submitted with the Biodiversity Gain Plan to specify the management and monitoring information for any significant onsite enhancements and offsite gains.

Similar to a Landscape and Ecological Management Plan (LEMP), a HMMP will give a detailed schedule of how the applicant plans to create and enhance habitats for biodiversity net gain in addition to how they plan to manage and monitor the habitat for at least 30 years. The level of detail within the HMMP should be proportionate to the scale of works and provide sufficient confidence in its delivery. The Natural England HMMP Template is recommended to ensure consistency.

There is a Companion Document for use with the main HMMP Template. It contains templates for each broad habitat type used in the statutory biodiversity metric and can be a useful resource when completing the HMMP.

For small sites, there is a separate HMMP Template that can only be used for sites that meet the criteria for 'small sites'. There is also a Small Sites Metric HMMP Habitat Guide which provides descriptions of proposed habitat types and conditions allowed in the Small Sites Metric (SSM). The purpose is to assist SSM users, who may not be professional ecologists, in preparing plans for long-term management of habitat types.

All HMMP Templates, Companion Document, and Habitat Guides can be downloaded from

Natural England Habitat Management and Monitoring Plan Templates and Guides