Biodiversity net gain · Exemptions
BNG exemptions: who is exempt, and what changed
BNG exemptions decide whether a planning permission in England carries the 10% biodiversity net gain condition at all.
The list changed for applications made on or after 6 August 2026, when SI 2026/790 added exemptions for sites of 0.2 hectares or less and for temporary development, and removed self-build.
This page sets out every exemption with its conditions, the transitional rules, and a checker you can run on your own scheme.
The exemptions
Every BNG exemption, with its conditions
Six exemptions are available to a planning application made today, and two more survive only for older applications.
| Regulation | Exemption | Conditions | Status for new applications |
|---|---|---|---|
| Reg 4 | De minimis | No impact on on-site priority habitat; under 25 m² of on-site habitat with a biodiversity value above zero; under 5 m of on-site linear habitat | Available |
| Reg 5 | Householder applications | Within the householder definition in DMPO art 2(1): extensions, conservatories, loft conversions | Available |
| Reg 6 | High Speed Rail | Part of, or ancillary to, the network in the High Speed Rail (Preparation) Act 2013 s.1(2) | Available |
| Reg 7 | Biodiversity gain sites | Development undertaken solely or mainly to create or enhance habitat for another development's gain | Available |
| Reg 7A | Sites of 0.2 hectares or less | Red line area of 0.2 ha or less; no impact on on-site priority habitat | Available from 6 Aug 2026 |
| Reg 7B | Temporary development | Whole development temporary; permission for five years or less; no impact on on-site priority habitat | Available from 6 Aug 2026 |
| Reg 8 | Self-build and custom build | No more than 9 dwellings on a site of no more than 0.5 ha | Removed 6 Aug 2026; saved for earlier applications |
| Reg 3 | Small ("minor") development | Applications made before 2 April 2024 | Spent |
The exemptions sit in the Biodiversity Gain Requirements (Exemptions) Regulations 2024, SI 2024/47, not in the Act.
Three of the live exemptions — de minimis, 0.2 hectares and temporary development — fall away if the development impacts any on-site priority habitat.
Defra’s exempt developments guidance defines the word: a development “impacts” a habitat if it decreases its biodiversity value.
Priority habitats are the habitats of principal importance listed by Defra and Natural England under section 41 of the NERC Act 2006.
A householder application is exempt whatever habitat it affects, because the DMPO definition is the only test.
Check your scheme
A BNG exemption checker, one question at a time
The checker asks the questions in the order the regulations answer them, and stops as soon as an exemption fits.
It starts with the application date, because 6 August 2026 decides which list applies.
Every branch is the wording of the regulation it names, so a “likely exempt” result tells you which exemption to cite in your application.
It is indicative only: the planning authority decides whether an exemption is met, on the evidence you give it.
If the result is “BNG applies”, the next step is the statutory biodiversity metric to measure the baseline.
Exemption checker
Question 1
Was the planning application made before 6 August 2026?
What changed
6 August 2026: two exemptions in, one out
SI 2026/790 was made on 9 July 2026 and came into force on 6 August 2026.
Regulation 3 inserted regulation 7A, for sites of 0.2 hectares or less, and regulation 7B, for temporary development.
It also omitted regulation 8, the self-build and custom build exemption.
Regulation 4 saves the old rules for applications made before 6 August 2026, and for section 73 permissions whose original application was made before that date.
So the date the planning application was made, not the date of the decision, decides which list applies.
The same instrument changed the gain hierarchy for development that is not major: on-site enhancement, on-site creation and registered off-site units are now equally preferred, with statutory credits still last, under article 37A of the Development Management Procedure Order.
legislation.gov.uk’s revised text of SI 2024/47 still showed regulation 8 in force and no regulations 7A or 7B when the Bible entry was last checked.
The changes are listed only in its “changes yet to be applied” panel, so read SI 2026/790 itself.
The dates that decide which list applies
- 12 Feb 2024BNG commences
All Part 3 applications, major and minor, except section 73A retrospective permissions.
- 2 Apr 2024Minor development exemption lapses
Only applications made before this date keep it.
- 1 May 2025Crown development in scope
Part 13 applications under the 1990 Act.
- 6 Aug 2026SI 2026/790 in force
0.2 ha and temporary exemptions added; self-build removed; hierarchy eased for non-major development.
Sources: SI 2024/44; SI 2024/47 reg 3; SI 2025/447 reg 2; SI 2026/790 reg 1(2)
Small sites
Small sites: exempt, simplified, or neither
“Small sites are exempt from BNG” has been wrong since 2 April 2024, and it is only partly right again since 6 August 2026.
| Scheme | Application made before 2 Apr 2024 | 2 Apr 2024 to 5 Aug 2026 | On or after 6 Aug 2026 |
|---|---|---|---|
| Minor development, 0.2 ha or less, no priority habitat impact | Exempt (reg 3) | In scope; small sites metric available | Exempt (reg 7A) |
| Minor development over 0.2 ha | Exempt (reg 3) | In scope; small sites metric available | In scope; on-site and off-site gains equally preferred |
| Self-build, 9 dwellings or fewer, 0.5 ha or less | Exempt | Exempt (reg 8) | In scope unless another exemption fits |
| Major development | In scope from 12 Feb 2024 | In scope | In scope; full hierarchy applies |
“Small development” in the 2024 regulations means development that is not major development in the DMPO sense: fewer than 10 dwellings, a site under 0.5 hectares where the number is unknown, under 1,000 square metres of new floorspace, and a site under 1 hectare.
Its temporary exemption covered only applications made before 2 April 2024, so between then and 6 August 2026 almost every minor scheme needed a 10% gain.
Minor schemes without priority habitat can use the small sites metric, a simpler calculation tool.
The 0.2 hectare exemption is narrower than “minor development”: Defra measures it as the area inside the red line boundary, and a single impacted patch of priority habitat removes it.
Not exemptions
Development that sits outside the condition
Some development is outside the biodiversity gain condition because the statute never reaches it, which is a different thing from an exemption.
Paragraph 17 of Schedule 7A excludes permission granted by a development order, which includes permitted development rights, and urgent Crown development.
The urgent Crown development limb now cross-refers to section 293C of the 1990 Act, substituted by SI 2025/418 from 1 May 2025.
Retrospective permissions under section 73A were left out when SI 2024/44 commenced BNG, and they have not been brought in.
Crown development applied for under Part 13 has been in scope since 1 May 2025, under SI 2025/447.
Nationally Significant Infrastructure Projects follow their own regime, covered on the BNG hub page.
| Route | Why BNG does not apply | Source |
|---|---|---|
| Permitted development | Granted by a development order, not on application | Sch 7A ¶17(a)(i) |
| Urgent Crown development | Excluded by the Act | Sch 7A ¶17(a)(ii), s.293C |
| Section 73A retrospective permission | Never commenced for BNG | SI 2024/44 reg 2(2) |
| Applications made before 12 Feb 2024 | Before commencement | Defra guidance |
| NSIPs | Separate regime from 2 Nov 2026 | Planning Act 2008 Sch 2A |
Making the case
How to show an exemption applies
An exemption is not claimed once and forgotten: the planning authority decides whether the scheme meets it, on the evidence submitted.
MHCLG’s planning practice guidance on BNG sets out what evidence may be needed for the de minimis exemption, and covers variations and the temporary development exemption.
For de minimis, that means showing the area of on-site habitat with a value above zero that the development affects, and the length of any hedgerow or other linear habitat.
For the 0.2 hectare exemption, the red line plan does most of the work, together with evidence that no priority habitat inside it is affected.
For temporary development, the permission itself must limit the development to five years or less.
Where no exemption fits, the condition applies and a biodiversity gain plan must be approved before work starts.
A shortfall that cannot be met on site is closed with off-site units or statutory credits.
For how nature duties fit the wider reporting picture, see the UK ESG reporting requirements map, and for a specific site you can book a free 15-minute call.
Frequently asked
Questions people ask
Which developments are exempt from BNG?
For planning applications made on or after 6 August 2026: householder applications; de minimis development; development of the High Speed Rail network; biodiversity gain sites created for another development; sites of 0.2 hectares or less within the red line boundary; and wholly temporary development permitted for five years or less. The last three do not apply where on-site priority habitat is impacted. Permitted development and urgent Crown development are outside the condition altogether.
Is a site under 0.2 hectares exempt from BNG?
Yes, for applications made on or after 6 August 2026, where the site area within the red line boundary is 0.2 hectares or less and the development does not impact any on-site priority habitat. The exemption was inserted into the exemption regulations as regulation 7A by SI 2026/790. It is not available for applications made before 6 August 2026.
Is self-build exempt from biodiversity net gain?
Not for planning applications made on or after 6 August 2026. SI 2026/790 omitted the self-build and custom build exemption from that date. It is saved for applications made before 6 August 2026, and for variations of a permission whose original application was made before that date.
What is the de minimis exemption for BNG?
Development that does not impact on-site priority habitat and impacts less than 25 square metres of on-site habitat with a biodiversity value above zero, and less than 5 metres of on-site linear habitat such as hedgerow. All three conditions must be met. Defra describes the area limit as 5 metres by 5 metres.
Do householder extensions need biodiversity net gain?
No. Householder applications, as defined in article 2(1) of the Development Management Procedure Order 2015, are exempt. Defra gives home extensions, conservatories and loft conversions as examples.
Are small sites exempt from BNG?
Not as a category. Minor development was only exempt for applications made before 2 April 2024. Since then it has been in scope, and it can use the simpler small sites metric. From 6 August 2026 a narrower exemption applies to sites of 0.2 hectares or less with no on-site priority habitat impact, and non-major development can choose freely between on-site and off-site gains.
Does BNG apply to temporary planning permission?
From 6 August 2026, not where the whole development is temporary, the permission is for five years or less, and no on-site priority habitat is impacted. Temporary development with a longer permission, or that impacts priority habitat, is in scope.
Does BNG apply to a section 73 variation?
It depends on the original permission. Defra's guidance says that where the original planning permission was not in scope of BNG, BNG will not apply to future variations in most cases. The saved self-build exemption also follows a section 73 permission whose original application was made before 6 August 2026.
Who decides whether a development is exempt?
The planning authority. The exemptions are statutory, but whether a particular scheme meets one is a matter for the authority on the evidence in the application. MHCLG's planning practice guidance explains what evidence may be needed to show the de minimis exemption applies.
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.ukSI 2024/47 — Biodiversity Gain Requirements (Exemptions) Regulations 2024, regs 4–8
The exemptions themselves. The revised text had not applied SI 2026/790 when last checked; read the "changes yet to be applied" panel.
- legislation.gov.ukSI 2026/790 — Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026
Reg 1(2): in force 6 August 2026. Reg 3: inserts regs 7A and 7B, omits reg 8. Reg 4: transitional savings.
- legislation.gov.ukTown and Country Planning Act 1990, Schedule 7A, paragraphs 13 and 17
The deemed biodiversity gain condition, and the development outside it (development orders, urgent Crown development).
- legislation.gov.ukSI 2024/44 — Environment Act 2021 (Commencement No. 8 and Transitional Provisions) Regulations 2024
Commencement from 12 February 2024 for Part 3 applications other than section 73A.
- legislation.gov.ukSI 2025/447, regulation 2 — commencement for Crown development
Part 13 applications in scope from 1 May 2025.
- legislation.gov.ukSI 2025/418 — Town and Country Planning (Fees and Consequential Amendments) Regulations 2025
Substituted the urgent Crown development cross-reference in Sch 7A ¶17(a)(ii) to section 293C.
- legislation.gov.ukDevelopment Management Procedure Order 2015, article 2(1)
The definitions of "householder application" and "major development".
- legislation.gov.ukDevelopment Management Procedure Order 2015, article 37A (as amended by SI 2026/790 reg 2)
The gain hierarchy for development that is not major, from 6 August 2026.
- legislation.gov.ukHigh Speed Rail (Preparation) Act 2013, section 1
The network the High Speed Rail exemption refers to.
- DefraBiodiversity net gain: exempt developments (last updated 6 August 2026)
The red line test for 0.2 hectares; householder examples; "impacts" means decreases biodiversity value; variations.
- MHCLGPlanning practice guidance: biodiversity net gain
Variations of permission, evidence for the de minimis exemption, and the temporary development exemption.
- Defra / Natural EnglandCalculate biodiversity value with the statutory biodiversity metric
Who can use the small sites metric.
- Defra / Natural EnglandHabitats and species of principal importance in England (NERC Act 2006 s.41 list)
The priority habitats that switch off three of the exemptions.
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