Biodiversity net gain and permitted development

Mandatory biodiversity net gain attaches to planning permissions granted on an application. Permission granted by a development order does not come from an application for planning permission, so the biodiversity gain condition does not bite on permitted development, and it does not bite on prior approval schemes either. For a developer weighing a Class MA office conversion against a full application, that is a material difference in cost and programme.

It is also a position built on statutory drafting rather than policy intent, which is why it should be checked against the current regulations before anyone relies on it.

How the gain condition is imposed

Schedule 7A to the Town and Country Planning Act 1990, inserted by the Environment Act 2021, works by deeming a condition into planning permission rather than by requiring councils to impose one. The condition prevents development from beginning until the local planning authority has approved a biodiversity gain plan, showing the post-development biodiversity value exceeds the pre-development value by at least 10 per cent, with the gain maintained for 30 years.

Two features of that mechanism matter here. The condition is automatic, so a council cannot forget to impose it and an applicant cannot negotiate it away. And it is attached to permission granted under Part 3 of the 1990 Act on an application, which is the hook the whole question hangs on.

Net gain became mandatory for major development on 12 February 2024 and for small sites on 2 April 2024.

Which permissions carry the condition

Permissions granted following an application carry it. That covers full applications, outline applications, and applications for householder development, subject to the statutory exemptions. Reserved matters do not attract a separate condition, because the gain plan is dealt with at outline stage.

Section 73 applications are less tidy. Where the original permission predates mandatory net gain or was itself exempt, a variation is generally treated as carrying the original position, but the analysis depends on the date and the terms of the permission being varied. On anything material, take advice rather than assume.

The regime is England only. Development in Wales, Scotland and Northern Ireland is governed by the relevant national framework, and the approach to biodiversity differs in each.

Permissions granted by a development order

The General Permitted Development Order grants planning permission directly, by order. No application for planning permission is made, no permission is granted on an application, and so the deemed condition has nothing to attach to.

The practical consequence is that a scheme delivered under permitted development carries no obligation to deliver a 10 per cent biodiversity uplift, no requirement to complete the statutory metric, and no gain plan to have approved before work starts. On a site with meaningful habitat, that is a material saving in both fees and programme.

Schedule 7A contains powers allowing the position to be changed by regulations, and the government has indicated at various points that the treatment of development orders could be revisited. Nothing here should be read as a permanent feature of the regime.

Prior approval schemes

Prior approval causes the most confusion, because it looks like an application and is processed like one.

It is not an application for planning permission. The permission comes from the development order itself, subject to a condition that the developer apply to the authority for a determination as to whether its prior approval is required for specified matters. Those matters are listed exhaustively in the relevant Class, and biodiversity is not among them for the classes developers use most.

So a Class MA change of use from commercial to residential, a Class Q barn conversion, or an upward extension under Part 20 does not carry the biodiversity gain condition, and the council cannot introduce biodiversity as a prior approval consideration that the Class does not list. The mechanics of that determination process, including what the authority may and may not take into account, are set out in the note on how the prior approval procedure actually works. The conditions and limitations attaching to Class Q show how tightly these rights are drawn in other respects.

None of this touches wildlife law. The Conservation of Habitats and Species Regulations 2017 and the Wildlife and Countryside Act 1981 apply to the works themselves regardless of the planning route. A barn with a bat roost still needs a survey and, if roosts will be affected, a licence from Natural England. A developer who reads the net gain position as permission to skip an ecology survey has misread it badly.

The exemptions, briefly

Where an application is made, four exemptions in the Biodiversity Gain Requirements (Exemptions) Regulations 2024 may apply: development below the de minimis threshold, householder development, self-build and custom housebuilding within the stated limits, and development of a registered biodiversity gain site.

Each has to be claimed on the application form with a reason. The de minimis route requires both that no onsite priority habitat is affected and that less than 25 square metres of habitat with a biodiversity value above zero, or less than 5 metres of linear habitat, is impacted. Temporary works count.

An exemption is not the same thing as falling outside the regime. The form asks whether the applicant believes the gain condition applies and, separately, which exemption is claimed, and the two answers are different for a permitted development scheme and an exempt application.

Why the position is easy to get wrong

Four reasons, in roughly the order they cause trouble.

The process resembles an application. Prior approval has a form, a fee, a consultation and an eight week clock, so everyone involved treats it as an application, and the biodiversity question gets asked and answered wrongly in both directions.

Councils apply local policy. A number of authorities had local net gain policies before the statutory regime, and officers sometimes try to apply them to prior approval schemes. They cannot, because the matters for determination are fixed by the Class.

Article 4 directions change the answer. Remove the permitted development right, and the scheme needs a full application, and the gain condition applies with it. On a site in an area where an article 4 direction is being consulted on, that timing difference is worth modelling.

And the guidance moves. This part of the regime has been amended more than once since February 2024, and secondary legislation can change it without primary legislation.

Checking before you rely on this

1. Confirm which route the scheme is actually using, and read the Class in the current consolidated version of the GPDO.
2. Check whether an article 4 direction affects the site, and when it takes effect.
3. Read the current Biodiversity Gain Requirements (Exemptions) Regulations 2024 as amended, rather than a summary.
4. Check the government's net gain guidance for any extension of the regime to development orders or to nationally significant infrastructure projects.
5. Commission the ecology survey anyway, because wildlife law and protected species licensing do not depend on the planning route.
6. Where the comparison between routes is finely balanced, price both, including the metric, any off-site units and the delay a gain plan approval adds.

Point six is the one that decides real schemes. The net gain obligation on a habitat-rich site can be the difference between two delivery routes, and it deserves a line in the appraisal rather than a footnote.

Where a full application is the route, the policy case for the scheme sits in the Planning Statement, and the net gain position should be stated there explicitly rather than left to the form.

Enter your postcode on PlanScope to see which reports a site is likely to need under either route.

This is general guidance, not legal advice. The statutory biodiversity metric is expected to be completed by a competent person under the Environment Act 2021 regime, and protected species work requires a suitably licensed ecologist. Check the current regulations and the position with your local planning authority before relying on any of this. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.