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Biodiversity net gain for developers - how to get ahead of secondary legislation

Economic Development | Blog

The National Planning Policy Framework already sets out a mitigation hierarchy: avoidance, minimisation, onsite restoration, offset and if these criteria cannot be met then technically planning should be refused.

Following the introduction of the Environment Act 2021, from November* 2023 the need to demonstrate at least a 10% biodiversity net gain (either on or off site) over and above a sites pre-development biodiversity value is set to become mandatory and apply to the majority of planning applications in England,

In addition, when the new Schedule 7A of the Town and Country Planning Act 1990 comes into force paragraph 13 sets to enforce that a standard pre-commencement condition is applied to all permissions granted in England, preventing lawful commencement of development until a ‘biodiversity gain plan’ is submitted to and approved by the Local Planning Authority.

What do developers need to do to get ahead?

Whilst the mandatory requirement is still some way away, now is the time for developers to apply best practice, and ensure biodiversity is an important and integral consideration when buying land and planning their developments, particularly in the case of greenfield development.

Although a finalised gain plan is not required at planning application stage, any development will need to provide an overview of its 10% biodiversity gain plan at application stage. At this point, it will need to be established if a net gain can be achieved on or off site, and thus, it is advantageous for developers to have an idea about the implications of any Biodiversity Impact Assessment (and any off site offsetting costs) before agreeing a purchase price for land and starting to design out sites.

In addition, it may be beneficial to submit the gain plan in full at the application stage, the advantage not only being that once planning is approved the net gain condition will be discharged and development can begin, but also it may assist with the planning process and the level of support that can be achieved for any development.

At planning application stage: Include details of the steps taken to minimise effects on biodiversity and how it will be enhanced. The consultation sets out the level of core information that is required at this stage including:


The pre-development biodiversity value


The proposed approach to enhancing biodiversity on-site


Any proposed off-site biodiversity enhancements (including the use of statutory credits) that have been planned or arranged for the development

For outline planning applications, it is also likely that additional information will be required in relation to the overall net gain strategy for the whole site and plans for phased delivery (where applicable).

You’ll also need to use the biodiversity metric 3.0 for calculating any impact – more detail can be found about this metric in Natural England’s User Guide.

At pre commencement planning condition stage: It is at this point a full gain plan must be submitted to and approved by the Local Planning Authority setting out the ‘detail’ for delivering that proposed at application stage.

The consultation sets out that the Local Planning Authority will only approve the biodiversity gain plan once they are satisfied that:


The biodiversity gain plan and completed biodiversity metric (submitted as the completed calculator document, not a ‘snapshot’ or summary) show a measurable net gain of at least 10% across all unit types (area-based, and where relevant, linear, and riverine habitats), having regard to policy on matters such as additionality


The information, including pre-development and post-development biodiversity values, presented in the biodiversity gain plan is complete and meets the statutory requirements


Any claimed gains (both on-site and off-site) are appropriately secured and allocated, including the point in the development process that these gains are to be delivered and a proportionate description of how enhancements will be managed and monitored

Some of the practicalities in terms of submission, timeframes and appeals process is yet to be fully published by the Secretary of State and there is speculation around exemptions, including likely exemptions for householder applications, change of use and self-build housing.

For more information about how the Environment Act and biodiversity net gain will affect your developments, contact Jenny Keen or another member of the planning team.

*Intended date following the two-year transition period outlined in the Defra’s January 2022 consultation

Published: 19th April 2022
Area: Development Strategy

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