The Biodiversity Net Gain Process

Submission and Assessment of an Application

When assessing an application the council must have confidence that the proposed development is capable of achieving at least 10% biodiversity net gain.

Although biodiversity net gain is a pre-commencement condition, it must be considered throughout the planning process and cannot be left until post-determination. Attention should be paid to the biodiversity gain hierarchy, spatial hierarchy; as well as the habitat management and monitoring of any significant on-site and/or any off-site habitat, when preparing and designing a proposal.

Consequently, in addition to national requirements, the council has also updated its local validation checklist to include the submission of some post-development biodiversity information as part of the minimum requirements to validate a planning application that is subject to the general biodiversity condition.

Should significant on-site habitat and/or off-site habitat need to be secured through a S106 planning obligation, this will need to be completed and signed prior to the planning permission being issued. Where a Section 106 planning obligation is required, this will be drafted by the Council’s Legal Service. The developer’s/landowner’s solicitor must undertake to pay the Council’s legal costs, provide ownership details for all land affected, and agree the wording so that it can be signed.

The General Biodiversity Condition

The Town and Country Planning Act has been amended to make every grant of planning permission deemed to have been granted subject to the following general biodiversity gain condition:

The development may not be begun unless: 
(a) a biodiversity gain plan has been submitted to the planning authority; and 
(b) the planning authority has approved the plan.

The purpose of the general biodiversity gain condition is to secure the ‘biodiversity objective’, which requires the post-development biodiversity value to exceed the pre-development biodiversity value of the on-site habitat by at least 10%.

Biodiversity net gain can be achieved through habitat creation or enhancement on-site and off-site; the purchase of biodiversity units from a habitat bank; or as a last resort through the purchase of statutory credits; or a mixture of these.

The Decision Notice

The general biodiversity gain condition has a separate legal basis in contrast to other planning conditions and will apply to all planning permissions, unless exempt.  The general biodiversity condition will not appear on the decision notice along with the list of planning conditions imposed on the application, rather it will be referenced in an informative note.

The general biodiversity gain condition cannot be varied or removed by an application under section 73 of the Town and Country Planning Act. It also cannot be discharged as part of the grant of planning permission.

Discharging the General Biodiversity Condition

Following grant of planning permission, a development subject to the general biodiversity condition cannot be commenced until it has been successfully discharged. This requires a biodiversity gain plan to be submitted to and approved by the council.  

Biodiversity Gain Plans

To discharge the general biodiversity condition, a completed biodiversity gain plan which sets out how the biodiversity gain objective of at least a 10% gain will be achieved, must be submitted along with the following supporting information:

  • A completed statutory biodiversity metric;
  • Pre-development and post-development plans showing the location of on-site habitat; 
  • A compensation Plan if the development affects irreplaceable habitats;
  • Biodiversity net gain register reference numbers if they’re using off-site units (purchased from a Habitat Bank);
  • Proof of purchase if buying statutory biodiversity credits.
  • A Habitat Management and Monitoring Plan (HMMP) setting out significant on-site gains will be managed and monitored. 

The plan must be submitted in writing, no earlier than the day after planning permission has been granted. There is no separate application form to be completed, but there will be an additional statutory £145 fee. Biodiversity gain plans should be submitted citing the planning application reference to which it relates.

A developer may submit a draft biodiversity gain plan alongside the planning application for information and discussion with the planning officer prior to determination of the application, although this is not a validation requirement. 

Templates for the Biodiversity Gain Plan and for Habitat Management and Monitoring Plan have been created by DEFRA and Natural England. Links to these can be found on the Validation, Guidance and Tools page.

Biodiversity Gain Plans for Phased Development

Where development is to be delivered in phases, the requirement for biodiversity gain plans differs. Instead of the standard approach as detailed above:

  • An Overall Biodiversity Gain Plan must be submitted to and approved by the council before any development can be begun; 
  • A Biodiversity Gain Plan for each phase must be submitted to and approved by the council before the development of that phase can be begun.

This recognises that phased development can often be implemented over a long period of time. The purpose of the Overall Biodiversity Gain Plan is to set a clear upfront framework for how the biodiversity gain objective of at least a 10% gain is expected to be met across the entire development.

The Biodiversity Gain Plan for each phase will then subsequently set out a phase’s contribution to biodiversity net gain and track progress towards the achieving the biodiversity gain objective.


To ensure that habitats establish and meet target condition within the timeframe provided in the final biodiversity metric calculations, it will be necessary for habitats to be monitored so that management strategies can respond and adapt if necessary.

The frequency of monitoring and reporting is to be agreed on a case-by-case basis. However, it is suggested that a monitoring report should be submitted by whoever is responsible to managing the delivery of significant on-site and off-site habitats in years 1, 2, 3, 4, 5, 10, 15, 20, 25 and 30  since the habitat creation or enhancement was completed. Should monitoring reports be proposed to be provided more or less frequently than this, ecologically sound justification should be provided.

All significant on-site and off-site habitats must be managed for a minimum 30 years period starting from the completion of the habitat creation and/or enhancement works (as defined and agreed between the council and the applicant). Should habitat delivery not be progress as agreed via the approved Biodiversity Gain Plan, the council will have powers of enforcement.

The council will be responsible for reporting monitoring outcomes for BNG in the case of habitats secured through planning conditions or obligations) to central Government on an annual basis.