Biodiversity net gain: which permissions escape the rules
The biodiversity gain condition attaches by reference to when the application was made, not when it was decided. Here are the commencement dates, the section 73 position and the five exemptions.
Biodiversity net gain transitional arrangements turn on one question: when was the application made. The biodiversity gain condition created by Schedule 7A to the Town and Country Planning Act 1990 is deemed to be attached to planning permissions granted on applications made on or after the relevant commencement date, so a permission granted in 2026 on an application submitted in January 2024 is generally outside the regime entirely. That is worth knowing before anyone commissions a metric.
The regime applies to most development but not to all of it, and the exemptions are drawn narrowly. Where a scheme sits close to a boundary, the position needs checking against the current regulations rather than against a summary written when the rules first took effect.
How the biodiversity gain condition was brought into force
Section 98 of and Schedule 14 to the Environment Act 2021 inserted Schedule 7A into the 1990 Act. Schedule 7A works by deeming a condition to be attached to every relevant planning permission: development may not begin until a biodiversity gain plan has been submitted to and approved by the planning authority, which must show at least a 10 per cent gain over the pre-development biodiversity value, secured for at least 30 years.
Commencement was staged by regulations, with separate dates for major and non-major development and a later date for nationally important infrastructure projects. The staging is the source of the transitional questions, because the condition attaches by reference to the application rather than to the decision.
Two consequences follow. A long-running application can escape the regime, and a fresh application for the same scheme cannot.
The major development date and the small sites date
The condition applied to major development from 12 February 2024 and to non-major development, commonly called small sites, from 2 April 2024. Those dates matter to the application, not the decision.
Major development takes its usual meaning: ten or more dwellings, or a site of 0.5 hectares or more where the number of dwellings is not known, or 1,000 square metres or more of floorspace, or a site of one hectare or more for other development. So a scheme that straddles the definition has two possible commencement dates, and the answer depends on how the application was described and validated. Our note on biodiversity net gain for small sites covers the differences that follow once the regime does apply.
Commencement for nationally important infrastructure projects has been deferred more than once. Check the current commencement position for that route rather than assuming a date.
Applications made before commencement, decided after
This is the transitional case that matters commercially. Where a valid application was made before the relevant date, the deemed condition does not attach, even if the decision comes years later.
The date the application was made is the date a valid application was received by the authority, which in practice means the validation date on the council's acknowledgement. Not the date you posted it, and not the date the case officer opened the file.
Several related situations follow the same logic:
- Reserved matters approvals on an outline permission granted before commencement are not new permissions, so the regime does not attach through them.
- Discharge of conditions applications are not new permissions either.
- A duplicate application submitted after commencement is a new application, and it is caught.
- An appeal against a refusal of a pre-commencement application relates to that application, so the transitional position is preserved.
That last point is worth weighing when deciding between an appeal and a resubmission. A resubmission restarts the clock and brings the biodiversity gain condition with it, along with the metric, the habitat survey season and the 30 year management obligation. On a marginal site those can be more onerous than the reason for refusal.
Illustrative example: a nine dwelling scheme validated in March 2024, refused on design grounds. Appealing preserved the pre-commencement position because the application predated 2 April 2024. Resubmitting would have required a baseline habitat survey in the following spring and a biodiversity gain plan before commencement. The circumstances are illustrative and used to show the trade-off.
Section 73 applications on earlier permissions
Section 73 is the awkward area. A section 73 permission is a new planning permission, which raises the question whether the biodiversity gain condition attaches to it when the original permission predates commencement.
Regulations made in 2024 modify how Schedule 7A applies to section 73 and set out how the pre-development biodiversity value is established where an earlier permission is being varied. The general effect is that a variation of a permission granted on a pre-commencement application is not brought into the regime by the variation alone, while a variation of a post-commencement permission carries the condition with it and may require the gain plan to be revisited where the change affects habitat.
The drafting is detailed and has been amended, so read the current regulations and the published guidance rather than relying on a general statement, including where the original permission was itself granted under section 73. Where a variation materially changes the site layout on a post-commencement permission, assume the gain plan will need updating and programme for it.
The exemptions and how narrowly they are drawn
Exemptions were made by regulations in 2024 and are precise rather than generous. The ones that come up are:
| Exemption | Practical limit |
|---|---|
| De minimis impact | No impact on an onsite priority habitat, and less than 25 square metres of onsite habitat and less than 5 metres of linear habitat affected |
| Householder applications | Development within the curtilage of a dwellinghouse under the householder application route |
| Self-build and custom housebuilding | No more than nine dwellings, site no larger than 0.5 hectares, meeting the self-build and custom build definition |
| Biodiversity gain sites | Development for the purpose of creating a registered gain site |
| Urgent Crown development | The separate urgent Crown development route |
Read the de minimis exemption carefully. Five metres of hedgerow is very little, and a site access through a boundary hedge usually exceeds it. The priority habitat test is absolute: any impact on onsite priority habitat removes the exemption regardless of area.
Permitted development and prior approval do not carry the deemed condition, because the condition attaches to permissions granted on an application. That is a real commercial difference between a Class MA prior approval and a full application for the same conversion, and it is one reason authorities press for full applications.
Evidence for relying on a transitional case
If you are relying on the application date, put the evidence in the file before anyone asks.
- The validation letter or email from the authority stating the date the application was made valid.
- The application reference and the entry on the authority's public register.
- Where the scheme is an appeal, the appeal reference and the decision under appeal.
- For section 73, the original permission, its application date and its decision date.
- A short note in the planning statement setting out the transitional position and the provision relied on.
Where you are relying on an exemption, the evidence is different in kind: a habitat plan and measured areas showing the de minimis thresholds are not exceeded, prepared by an ecologist. A Biodiversity Net Gain Assessment and the statutory metric must be completed by a competent person under the Environment Act 2021 regime, and the biodiversity gain plan is approved by the local planning authority, so an AI-assisted draft is a starting point for that professional rather than a substitute for their work.
Where the position is unclear
Say so in the planning statement and ask the authority to confirm. Authorities have been inconsistent about section 73 and about the small sites boundary, and a permission granted without the gain plan being approved where the condition did apply is a problem that surfaces later, when funding or sale due diligence finds it.
Two practical rules. Where the cost of a metric is small relative to the scheme and the position is arguable on the face of the regulations, do the metric and secure the position. And where the regime clearly applies, programme the baseline habitat survey to the growing season rather than the planning timetable, because a spring survey window missed is a year lost.
The position described here is as at the date of publication, drawn from Schedule 7A to the 1990 Act, the Environment Act 2021 and the 2024 commencement and exemption regulations. Verify the current commencement and exemption position on gov.uk before relying on it, and follow reform news through the PlanScope planning law timeline and the government's published guidance. The 2026 NPPF restructure changed citation practice at the same time, which matters when older reports are being reused.
This is general guidance, not legal advice, so check the position with your local planning authority or a qualified professional before relying on it. PlanScope produces AI-assisted drafts structured to UK planning policy and flags the site facts it cannot verify. Browse all 66 PlanScope report types.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Which date decides whether biodiversity net gain applies?
The date the application was made, meaning the date a valid application was received by the authority, rather than the date of the decision. The condition applied to major development from 12 February 2024 and to non-major development from 2 April 2024. A permission granted long afterwards on an earlier application is generally outside the regime.
Does an appeal preserve the transitional position?
An appeal relates to the original application, so a pre-commencement application that goes to appeal keeps its transitional position. A resubmission is a new application and is caught. That makes the choice between appealing and resubmitting a biodiversity net gain question as well as a planning one on sites where the metric would be difficult.
Does the condition attach to a section 73 variation?
Regulations made in 2024 modify how Schedule 7A applies to section 73 and set out how the pre-development biodiversity value is established. The general effect is that varying a permission granted on a pre-commencement application does not itself bring the scheme into the regime, while varying a post-commencement permission carries the condition with it. Read the current regulations, because the drafting has been amended.
What is the de minimis exemption?
It applies where the development does not affect any onsite priority habitat and affects less than 25 square metres of onsite habitat and less than 5 metres of linear habitat such as hedgerow. Both area tests are small, and the priority habitat test is absolute, so a site access driven through a boundary hedge will usually take the scheme outside the exemption.
Does permitted development need biodiversity net gain?
The deemed condition attaches to planning permissions granted on an application, so permitted development and prior approval routes do not carry it. That is a real commercial difference between a prior approval conversion and a full application for the same scheme, and it is one reason authorities often prefer a full application.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.