BNG 0.2 Hectare Exemption in Force 31 July 2026: Small Sites Biodiversity Net Gain, What Changes Today

Last updated: July 31, 2026

Quick Answer: As of 31 July 2026, the BNG 0.2 hectare exemption is now in force, meaning any development site with a total area below 0.2 hectares (2,000 m²) is automatically exempt from the mandatory biodiversity net gain requirement, provided it does not impact a priority habitat. Defra estimates this will exempt approximately 50% of residential planning permissions that were previously subject to BNG. The exemption applies to all development types, including residential and commercial, but the priority-habitat carve-out means size alone does not guarantee exemption.

Key Takeaways

• From today, 31 July 2026, sites under 0.2 ha (2,000 m²) are exempt from mandatory BNG unless they affect a priority habitat.
• The exemption covers all development types: residential, commercial, mixed-use, and others.
• Approximately 50% of residential planning permissions previously subject to BNG are now expected to fall outside the requirement (Defra estimate).
• Priority habitats, including ancient woodland, lowland meadow, and hedgerows, trigger full BNG obligations regardless of site size.
• Off-site biodiversity units carry equal weight to on-site delivery for minor developments that remain subject to BNG.
• BNG becomes mandatory for Nationally Significant Infrastructure Projects (NSIPs) from 2 November 2026.
• The NPPF and other regulatory duties (such as the biodiversity duty under the Environment Act 2021) still apply even where BNG is exempt.
• Developers should carry out a habitat survey before assuming exemption, a professional assessment is the only reliable way to confirm priority-habitat status.

What Is the 0.2 Hectare Exemption for Biodiversity Net Gain?

The 0.2 hectare exemption is a statutory threshold below which a development site is not required to demonstrate a 10% biodiversity net gain as a condition of planning permission. It was introduced through secondary legislation under the Environment Act 2021 and comes into force today, 31 July 2026.

In practical terms, if the total footprint of a proposed development, including all land within the red-line boundary, is less than 0.2 hectares (equivalent to 2,000 square metres, or roughly half an acre), the applicant does not need to submit a biodiversity metric calculation, a biodiversity gain plan, or a habitat management agreement as part of the planning application. This removes a significant administrative and cost burden for small-site developers.

The exemption is area-based, not unit-based. It does not matter whether the site will deliver one dwelling or ten; what matters is the total land area within the application boundary.

For a broader overview of how BNG works before applying the exemption test, see this biodiversity net gain explained guide.

Which Developments Qualify for the 0.2 Hectare BNG Exemption?

Any development in England with a red-line boundary area below 0.2 ha qualifies for the exemption, provided no priority habitat is present or affected within that boundary. This applies to:

• Small residential schemes (including single dwellings, conversions, and small housing clusters)
• Minor commercial developments
• Mixed-use schemes where the combined site area is under 0.2 ha
• Permitted development applications where BNG would otherwise apply

The priority-habitat carve-out is critical. If any part of the site contains or directly affects a priority habitat, such as ancient woodland, lowland calcareous grassland, hedgerows, traditional orchard, or blanket bog, the exemption does not apply, regardless of how small the site is. The Chartered Institute of Ecology and Environmental Management (CIEEM) has consistently advised that priority habitat identification requires a competent ecologist's assessment, not a desktop assumption.

Edge case to watch: A developer with a 0.18 ha brownfield site might assume automatic exemption. If that site contains a section of species-rich hedgerow (a UK Biodiversity Action Plan priority habitat), full BNG obligations apply. The exemption is lost the moment a priority habitat is confirmed within the red-line boundary.

How Does the Small Sites BNG Exemption Work in Practice?

The exemption works as a self-certification mechanism within the planning application. Where a developer believes their site qualifies, they declare the exemption on the planning application form and are not required to submit a biodiversity gain plan. The local planning authority (LPA) can challenge this declaration if there is evidence of priority habitat on site.

The process for a small-site developer looks like this:

1. Measure the red-line boundary area. If it is 0.2 ha or above, the exemption does not apply.
2. Commission a habitat survey (at minimum a Phase 1 Habitat Survey) to confirm whether any priority habitats are present or likely to be affected.
3. If no priority habitats are found and the site is under 0.2 ha, declare the exemption on the application form.
4. If priority habitats are present, proceed with a full BNG assessment regardless of site size.
5. Retain survey records in case the LPA requests supporting evidence.

For guidance on what a full BNG assessment involves when it is required, see what is in a biodiversity net gain assessment.

Do I Need to Do BNG for Developments Under 0.2 Hectares?

No, with one important exception. If the site is under 0.2 ha and contains no priority habitat, mandatory BNG does not apply from today, 31 July 2026. However, three separate obligations can still require ecological consideration:

• The biodiversity duty under Section 40 of the Natural Environment and Rural Communities Act 2006 (as strengthened by the Environment Act 2021) requires all public authorities, including LPAs, to have regard to biodiversity. This can influence planning conditions even where BNG is exempt.
• The NPPF requires that planning decisions contribute to and enhance the natural and local environment. LPAs retain discretion to request ecological information where harm to biodiversity is a material consideration.
• Protected species legislation under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017 applies independently of BNG. A site under 0.2 ha with bat roosts, great crested newts, or nesting birds still requires appropriate ecological surveys and mitigation.

The Country Land and Business Association (CLA) has noted that smaller rural developers in particular should not conflate BNG exemption with a general licence to disregard ecological impacts.

What's the Difference Between the 0.2 Hectare Exemption and Full BNG Requirements?

For sites that do fall under full BNG requirements, off-site provision carries equal weight to on-site delivery for minor developments. This means a small-site developer who is not exempt can purchase biodiversity units from an approved habitat bank rather than delivering habitat on the development site itself. See biodiversity net gain off-site or on-site delivery for a comparison of both routes.

Why Priority Habitats Matter Regardless of Site Size

Priority habitats are irreplaceable or difficult-to-restore ecosystems identified under Section 41 of the Natural Environment and Rural Communities Act 2006. Their presence on a site, however small, triggers full BNG obligations because the biodiversity metric assigns them very high unit values and the government's policy intent is that no development should result in a net loss of these habitats.

Common priority habitats found on small sites include:

• Hedgerows (particularly species-rich hedgerows on agricultural boundaries)
• Traditional orchards (often found in infill residential plots)
• Lowland meadow (including garden areas with unimproved grassland)
• Ponds (any standing water body under 2 ha)
• Woodland (including scrub transitioning to woodland)

CIEEM guidance makes clear that a competent ecologist, not an automated desktop tool, must make the final determination on priority habitat presence. For small-site developers unfamiliar with ecological survey requirements, the BNG for small development projects resource provides practical context.

Interaction with the NPPF and Other Regulatory Duties

The BNG 0.2 hectare exemption in force from 31 July 2026 does not override the National Planning Policy Framework. The NPPF's policies on protecting and enhancing biodiversity remain material considerations in all planning decisions. LPAs can still refuse applications or impose conditions where ecological harm is identified, even on exempt small sites.

The government's position, as set out in supporting guidance on gov.uk, is that the exemption reduces bureaucratic burden without removing the broader duty to protect nature. Developers should treat exemption as relief from the formal BNG metric process, not as permission to ignore ecological impacts altogether.

BNG for NSIPs: The 2 November 2026 Date

While small sites gain relief today, the BNG regime is simultaneously expanding at the other end of the scale. Mandatory biodiversity net gain for Nationally Significant Infrastructure Projects (NSIPs), including major energy, transport, and water infrastructure, comes into force on 2 November 2026. This is a separate statutory instrument and does not affect the small-site exemption, but it signals that the overall BNG framework continues to widen.

Can I Combine Multiple Small Sites to Avoid BNG Requirements?

No. Attempting to artificially subdivide a larger development into multiple sub-0.2 ha parcels to circumvent BNG is not a legitimate strategy. LPAs and the Planning Inspectorate assess the overall development as a whole. Where applications are clearly related, same developer, same site, same time period, they will be assessed on their combined footprint. This approach would also risk refusal on other planning grounds and could constitute a material misrepresentation in the application.

Practical Checklist for Small-Site Developers (As of 31 July 2026)

Use this checklist before submitting a planning application on a site you believe is exempt:

• Confirm the red-line boundary area is below 0.2 ha (2,000 m²)
• Commission a Phase 1 Habitat Survey from a qualified ecologist
• Confirm no Section 41 priority habitats are present within or adjacent to the site boundary
• Check for protected species (bats, great crested newts, nesting birds), these require separate survey work
• Confirm the development type is not an NSIP or otherwise excluded from the exemption
• Declare the exemption on the planning application form with supporting survey evidence
• Retain all survey records for at least the duration of the planning permission
• Consult the LPA's local biodiversity requirements, some authorities have additional local policies

For developers whose projects do not qualify for exemption, how to achieve 10% biodiversity net gain sets out the delivery options clearly.

What Should I Do Now to Prepare, Even If My Site Is Exempt?

Exemption from mandatory BNG does not mean ecological considerations disappear from the planning process. The most practical steps for small-site developers right now are:

1. Get a habitat survey done early, before design is finalised. Discovering a priority habitat late in the process is costly.
2. Brief your architect or design team on the priority-habitat carve-out so site layouts avoid unnecessary habitat loss.
3. Check your LPA's local plan for any biodiversity policies that go beyond the national BNG requirement.
4. If BNG does apply, engage a biodiversity surveyor early to explore whether on-site or off-site delivery is more cost-effective for your scheme. See achieving biodiversity net gain without the risk for a practical guide to managing delivery risk.
5. Document everything. Even where exemption applies, a paper trail demonstrating due diligence protects developers against future challenge.

FAQ

Q: Does the 0.2 ha exemption apply to commercial as well as residential development?
Yes. The exemption is not restricted by development type. Any development in England with a site area below 0.2 ha and no priority habitat qualifies, whether residential, commercial, mixed-use, or otherwise.

Q: What counts as "affecting" a priority habitat for the purposes of the exemption?
A priority habitat is considered affected if it falls within the red-line boundary of the application or if the development would directly damage or destroy it, for example, by removing a hedgerow that forms the site boundary. Indirect impacts may also be relevant depending on the LPA's assessment.

Q: Is a Phase 1 Habitat Survey legally required to claim the exemption?
It is not a statutory requirement, but it is strongly advisable. Without survey evidence, a developer cannot reliably confirm the absence of priority habitats, and an LPA can challenge an exemption declaration if there is reason to believe priority habitats are present.

Q: Does the exemption apply in Wales, Scotland, or Northern Ireland?
No. BNG under the Environment Act 2021 applies in England only. Wales, Scotland, and Northern Ireland have separate legislative frameworks for biodiversity in planning.

Q: If my site is exempt, do I still need to submit any ecological documents with my planning application?
You are not required to submit a biodiversity gain plan or metric calculation. However, many LPAs will still expect a habitat survey or ecological appraisal as part of the application, particularly if the site has any ecological sensitivity.

Q: What if my site is exactly 0.2 ha, is it exempt?
No. The threshold is "less than 0.2 ha." A site of exactly 0.2 ha (2,000 m²) is not exempt and is subject to full BNG requirements.

Q: Where can I find out if my site contains a priority habitat before commissioning a survey?
Defra's Magic Map application and Natural England's Priority Habitat Inventory are publicly available desktop tools that provide an initial indication, but they are not definitive. A qualified ecologist's field survey is required to confirm presence or absence.

Conclusion

The BNG 0.2 hectare exemption coming into force on 31 July 2026 is a meaningful change for small-site developers across England. With approximately half of residential planning permissions now expected to fall outside the mandatory BNG requirement, the administrative and cost burden on minor developments is substantially reduced.

That said, exemption is conditional, not automatic. The priority-habitat carve-out means that a habitat survey remains the essential first step for any small-site application. Developers who skip this step risk discovering mid-application that their site is not exempt after all, a far more disruptive and expensive outcome than commissioning a survey at the outset.

The practical path forward is straightforward: measure your site, survey your habitats, and confirm your position before design work is locked in. Where BNG does apply, off-site delivery options are available and carry equal weight to on-site provision, giving small developers genuine flexibility. For guidance tailored to your project, contact a biodiversity surveyor who can confirm your exemption status and, where needed, map out the most cost-effective BNG delivery route.

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