BNG · Planning in England
Biodiversity net gain: the rules in England in 2026
Biodiversity net gain requires most new development in England to leave habitat at least 10% better than it found it, under Schedule 7A to the Town and Country Planning Act 1990.
The rules moved twice this year: new exemptions took effect on 6 August 2026, and infrastructure projects come into scope on 2 November 2026.
This guide sets out the biodiversity net gain requirements as they stand on 30 September 2026.
What BNG is
A deemed condition, not a refusal ground
Every planning permission for development of land in England is deemed to carry a condition that development may not begin until a biodiversity gain plan has been submitted and approved.
That is paragraph 13 of Schedule 7A, and it is the mechanism that makes BNG bite.
The plan must show that the biodiversity value attributable to the development exceeds the pre-development value of the on-site habitat by at least 10%.
Under paragraph 2, the value attributable to the development is the total of three things: the post-development on-site value, any registered off-site gain allocated to it, and any statutory credits bought for it.
So the 10% does not have to be delivered on the site itself.
The Secretary of State can change the percentage by regulations, and none had been made as at 30 September 2026.
Biodiversity is measured in units using the statutory biodiversity metric, which the Secretary of State publishes and lays before Parliament.
Schedule 7A applies to grants of planning permission in England.
Wales, Scotland and Northern Ireland run their own planning systems.
Commencement
Four start dates, not three
SI 2024/44 brought BNG into force on 12 February 2024 for every planning application under Part 3 of the 1990 Act, major and minor alike.
There was never a separate commencement for small sites: they had a temporary exemption, in SI 2024/47, for applications made before 2 April 2024.
Crown development came into scope on 1 May 2025 under SI 2025/447, a limb most summaries leave out.
For nationally significant infrastructure projects, SI 2026/492 commenced the machinery on 7 May 2026, but the obligation bites only for development consent applications made on or after 2 November 2026.
That later date comes from the biodiversity gain statements themselves, not from any statutory instrument.
Retrospective permissions under section 73A are outside BNG because it was never commenced for them.
- 12 Feb 2024Planning applications
All Part 3 applications, major and minor.
- 2 Apr 2024Small-sites exemption lapses
For applications made on or after this date.
- 1 May 2025Crown development
Applications under Part 13 of the 1990 Act.
- 7 May 2026NSIP machinery in force
- 6 Aug 2026Exemptions and hierarchy amended
- 2 Nov 2026NSIPs in scope
DCO applications made on or after this date.
Sources: SI 2024/44 · SI 2024/47 · SI 2025/447 · SI 2026/492 · SI 2026/790
Biodiversity net gain exemptions
What is exempt from 6 August 2026
The exemptions changed on 6 August 2026, and the consolidated text on legislation.gov.uk had not caught up when this page was checked.
| Exemption | Test | Status |
|---|---|---|
| De minimis | No impact on a priority habitat, less than 25 m² of habitat with value above zero, and less than 5 m of linear habitat | Live |
| Householder applications | As defined in the Development Management Procedure Order | Live |
| High speed rail | The high speed rail network | Live |
| Biodiversity gain sites | Sites serving another development’s gain | Live |
| Small sites | Site no larger than 0.2 hectares, no impact on a priority habitat | New — applications made on or after 6 Aug 2026 |
| Temporary development | Wholly temporary, no longer than five years, no impact on a priority habitat | New — applications made on or after 6 Aug 2026 |
| Self-build and custom build | Up to 9 dwellings on up to 0.5 hectares | Removed — saved only for applications made before 6 Aug 2026 |
Separately, Schedule 7A itself excludes development granted by a development order, which covers permitted development, and urgent Crown development.
Brownfield sites and developments with an environmental impact assessment are not exempt as such; they are in scope unless one of the listed exemptions applies.
Defra says the August changes apply to new applications from 6 August 2026, and applications already made stay under the earlier rules.
The hierarchy
The biodiversity gain hierarchy is statutory
The order of preference is law, not guidance.
Article 37A of the Development Management Procedure Order 2015 sets out the biodiversity gain hierarchy “in the following order of priority”.
The gain plan must describe how the hierarchy is applied, including any reasons for not following the order, under article 37C(2)(e).
The planning authority must take into account how it is applied and the reason for any departure — or the absence of one — under article 37D(2).
Schedule 7A itself imposes no order, which is why the hierarchy is often mistaken for guidance.
Since 6 August 2026, for development that is not major development, on-site enhancement, on-site creation and registered off-site gain sit at the same level of preference, with credits still the last resort.
Article 37A, in order
| Step | Action |
|---|---|
| 1 | For high-distinctiveness habitat: avoid adverse effects, then mitigate |
| 2 | Enhance on-site habitat |
| 3 | Create on-site habitat |
| 4 | Allocate registered off-site gain |
| 5 | Buy statutory biodiversity credits |
Calculation
The statutory metric, and how the percentage works
Baseline
Survey and map the habitats on site, and calculate the pre-development biodiversity units with the statutory metric.
Proposal
Map habitats retained, enhanced and created, apply their target condition, and calculate the post-development units.
The percentage
Total the value attributable to the development — on-site, allocated off-site gain and credits — and compare it with the baseline. It must exceed the baseline by at least 10%.
Separate modules
Hedgerows and watercourses are measured in their own unit types, separately from area habitat.
The laid document is “The Statutory Biodiversity Metric — User Guide”, and it carries no version number.
The calculation tools are versioned, and Defra’s metric tools page says any version of the statutory tools may be used because updates do not change unit outputs.
Calculations made with Biodiversity Metric 4.0 or earlier are not accepted in planning applications.
A small sites metric tool exists for smaller developments, and the survey behind any metric is usually carried out by an ecologist.
Delivery options
On site, off site, or credits
Enhance or create habitat within the site
Highest in the hierarchy for major development.
Significant enhancements count only if secured for at least 30 years.
Registered off-site gain
Habitat on another site, registered on the biodiversity gain sites register and allocated to the development.
Usually provided by a landowner or habitat bank.
Statutory biodiversity credits
Bought from the government under section 101 of the Environment Act 2021.
A spatial risk multiplier means two credits for every unit you need.
Section 101 lets the Secretary of State set credit prices and requires them to be published, and requires prices that do not discourage landowners from registering off-site gain sites.
Defra publishes the statutory credit price list, tiered by habitat, and reviews it every six months with at least ten weeks’ notice.
Defra says the prices include a mark-up so they do not undercut the off-site market, the spatial risk multiplier is not included in the listed price, and VAT is not charged.
Off-site units are sold by landowners and habitat bank operators at prices they set themselves; this page does not characterise them.
Thirty years
What the 30-year rule actually covers
The 30-year period in paragraph 9 of Schedule 7A is narrower than it is usually described.
A significant on-site increase in biodiversity counts towards the gain only if the enhancement will be maintained for at least 30 years after the development is completed.
That must be secured by a planning condition, a planning obligation or a conservation covenant.
The condition applies only where the planning authority considers the increase significant in relation to the pre-development value.
The Secretary of State can lengthen the period by regulations, but not shorten it.
For infrastructure projects under the Planning Act 2008, the percentage is a floor of at least 10% set in each gain statement, and the maintenance period is whatever that statement specifies.
In practice
Planning an application under BNG
Design for the gain
- Commission a baseline habitat survey early.
- Check whether an exemption genuinely applies, and on which date the application will be made.
- Run the statutory metric on the baseline and the proposal.
- Design out loss of high-distinctiveness habitat first.
- Talk to the local planning authority about its information requirements.
Discharge the condition
- Prepare the biodiversity gain plan with the contents article 37C requires.
- Explain how the hierarchy was applied, and why any step was skipped.
- Secure off-site gain on the register, or buy credits, before approval.
- Put 30-year management and monitoring in place where it is required.
- Obtain approval before development begins.
BNG and reporting
BNG is planning law, not a reporting duty
BNG sits alongside a planning application, not a sustainability report.
No UK law requires an ordinary company to report on biodiversity in its annual report, and the biodiversity duty in section 40 of the NERC Act 2006 binds public authorities, not companies.
Companies that do disclose on nature do so voluntarily, usually against the TNFD recommendations or GRI 101; our biodiversity reporting guide covers that side.
Our sister site explains how nature fits into wider sustainability reporting.
For the carbon and energy side of the same development portfolio, see Streamlined Energy and Carbon Reporting.
If it would help to talk through how BNG connects to your wider reporting, book a free 15-minute call.
Frequently asked
Questions people ask
What is biodiversity net gain?
Biodiversity net gain (BNG) is the rule in England that development must leave the biodiversity value of land at least 10% higher than it was before. It works through a condition deemed to be attached to every planning permission: development may not begin until a biodiversity gain plan has been submitted and approved by the planning authority.
When did biodiversity net gain become mandatory?
For planning applications under Part 3 of the Town and Country Planning Act 1990, from 12 February 2024. Small sites had a temporary exemption for applications made before 2 April 2024. Crown development came into scope on 1 May 2025, and nationally significant infrastructure projects come into scope for development consent applications made on or after 2 November 2026.
Does biodiversity net gain apply in Wales or Scotland?
No. Schedule 7A to the Town and Country Planning Act 1990 is confined to planning permission in England. Wales, Scotland and Northern Ireland have their own planning systems and their own approaches to biodiversity in planning.
What development is exempt from biodiversity net gain?
From 6 August 2026 the exemptions are: de minimis development that does not affect a priority habitat and affects less than 25 square metres of habitat and less than 5 metres of linear habitat; householder applications; the high speed rail network; biodiversity gain sites; sites no larger than 0.2 hectares that do not affect a priority habitat; and temporary development of up to five years that does not affect a priority habitat. The self-build and custom build exemption was removed for applications made on or after 6 August 2026.
Is the biodiversity gain hierarchy a legal requirement?
Yes. Article 37A of the Development Management Procedure Order 2015 sets out the biodiversity gain hierarchy in order of priority, the gain plan must explain any departure from it, and the planning authority must take the reasons, or their absence, into account. Since 6 August 2026, for development that is not major development, on-site enhancement, on-site creation and registered off-site gain rank equally, with statutory credits still last.
How long must biodiversity net gain be maintained?
For at least 30 years after the development is completed, where it is secured by a planning condition, a planning obligation or a conservation covenant. The 30-year condition applies to significant on-site enhancements the planning authority counts towards the gain. It is not a blanket duty over every development site.
How much do statutory biodiversity credits cost?
Defra publishes the statutory credit price list and reviews it every six months, giving at least ten weeks’ notice of changes. A spatial risk multiplier means you must buy two statutory credits for every biodiversity unit you need, and the multiplier is not included in the published prices. VAT is not charged on the credits.
Which version of the biodiversity metric should I use?
The statutory biodiversity metric. Defra says any version of the statutory metric tools may be used, because updates do not change the unit outputs. Calculations made with Biodiversity Metric 4.0 or earlier will not be accepted in planning applications.
Do companies have to report biodiversity net gain in their annual report?
No. BNG is a planning requirement on developments, not a corporate reporting duty. No UK law requires an ordinary company to report on biodiversity in its annual report; corporate biodiversity reporting is voluntary and framework-driven.
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner. Secondary commentary is never the source for a number.
- legislation.gov.ukTown and Country Planning Act 1990, Schedule 7A — biodiversity gain
¶2(3) the 10%, ¶9 the 30 years, ¶13 the deemed condition, ¶17 the statutory exceptions.
- legislation.gov.ukTCPA 1990, Schedule 7A ¶2 — the biodiversity gain objective
The value attributable to the development counts on-site, off-site and credits together.
- legislation.gov.ukSI 2024/44 — Environment Act 2021 (Commencement No. 8 and Transitional Provisions) Regulations 2024
Commenced BNG for Part 3 applications on 12 February 2024.
- legislation.gov.ukSI 2024/47 — Biodiversity Gain Requirements (Exemptions) Regulations 2024
The exemptions; ⚠ the revised text does not yet show the 6 August 2026 changes.
- legislation.gov.ukSI 2025/447 — commencement for Crown development
Part 13 applications from 1 May 2025.
- legislation.gov.ukSI 2026/492 — commencement of the NSIP provisions
Machinery in force 7 May 2026.
- legislation.gov.ukSI 2026/790 — Biodiversity Gain (Amendments and Transitional Provisions) (England) Regulations 2026
In force 6 August 2026: new exemptions, self-build removed, hierarchy amended.
- legislation.gov.ukDevelopment Management Procedure Order 2015, Part 7A (arts 37A–37D)
The statutory biodiversity gain hierarchy and gain plan contents.
- legislation.gov.ukEnvironment Act 2021, section 101 — biodiversity credits
The power under which statutory credit prices are set and published.
- legislation.gov.ukPlanning Act 2008, Schedule 2A — NSIPs
¶3(2): the specified percentage must be at least 10%.
- DefraStatutory biodiversity credit prices
The price list, the spatial risk multiplier and the six-monthly review.
- DefraStatutory biodiversity metric tools and guides
Any version of the statutory tools may be used; Metric 4.0 is not accepted.
- DESNZ / DefraBiodiversity gain statements for nationally significant infrastructure projects
The ten statements; DCO applications from 2 November 2026.
- legislation.gov.ukNERC Act 2006, section 40 — the biodiversity duty
A duty on public authorities, not on companies.
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