Last updated: June 26, 2026
Quick Answer: On 15 April 2026, the Government published its formal response to DEFRA's May 2025 consultation, confirming a package of BNG reforms expected to take effect by end of July 2026. The headline change is a new 0.2 hectare area-based exemption that could remove approximately 50% of residential planning permissions from mandatory Biodiversity Net Gain requirements. Developers, planners, and ecologists working on smaller sites need to understand which projects qualify, what replaces the old self-build exemption, and how the hierarchy changes for minor development affect off-site delivery.
Key Takeaways
- A new 0.2 hectare area-based exemption is expected to be introduced by 31 July 2026, subject to parliamentary scheduling.
- This exemption is estimated to remove around half of all residential planning permissions from mandatory BNG obligations. [6]
- The existing small-scale self-build and custom-build BNG exemption will be removed from 31 July 2026.
- Temporary planning permissions of five years or less will be exempt from BNG requirements.
- For minor development, off-site biodiversity gains will rank equal to on-site gains in the biodiversity gain hierarchy. [8]
- A separate brownfield consultation covering sites up to 2.5 hectares closed on 10 June 2026.
- BNG for Nationally Significant Infrastructure Projects (NSIPs) applies to applications on or after 2 November 2026, with no retrospective effect.
- Priority habitats remain a key constraint: even exempt sites must still comply with NPPF environmental protections.
- New exemptions are also proposed for biodiversity-led schemes and amenity enhancement projects such as parks and playing fields. [1]
What Is Biodiversity Net Gain and How Does It Work?
Biodiversity Net Gain is a legal requirement under Schedule 7A of the Environment Act 2021, mandating that most new developments in England deliver a measurable 10% improvement in biodiversity value compared to the pre-development baseline. It applies to planning permissions granted after the relevant commencement dates: February 2024 for major development, April 2024 for minor development, and from 2 November 2026 for NSIPs.
The process works as follows:
- A qualified ecologist conducts a baseline habitat survey and runs the statutory biodiversity metric (currently Metric 4.0) to calculate existing biodiversity units on site.
- The metric is re-run for the proposed post-development layout to identify the biodiversity unit deficit.
- The developer must close that deficit, plus deliver the mandatory 10% uplift, through on-site habitat creation, off-site habitat units purchased from a registered habitat bank, or statutory biodiversity credits purchased from Natural England as a last resort.
- A Biodiversity Gain Plan is submitted to and approved by the local planning authority before development can commence.
- Habitat management obligations run for a minimum of 30 years, secured by a planning condition or legal agreement.
For a practical overview of the full process, see this guide to achieving 10% Biodiversity Net Gain.
Biodiversity Net Gain BNG Reforms July 2026: The 0.2 Hectare Exemption Explained
The 0.2 hectare exemption is an area-based threshold: any development with a total site area of 0.2 hectares or less will be exempt from mandatory BNG, provided the site does not contain or impact priority habitats. [6] This is distinct from the existing "de minimis" rule, which exempts development affecting fewer than 25 square metres of habitat or five metres of linear habitat.
Key points about the new exemption:
- It applies across all development types, not just residential.
- Priority habitats on or adjacent to the site remain a hard constraint. A site under 0.2 ha that contains, for example, a patch of ancient woodland or species-rich grassland would not automatically qualify.
- NPPF environmental protections continue to apply to all exempt sites.
- The exemption is expected to be introduced via secondary legislation by 31 July 2026, subject to parliamentary scheduling. [5]
Why it matters: An estimated 50% of residential planning permissions fall below the 0.2 ha threshold. [6] For small housebuilders and infill developers, this represents a significant reduction in pre-application survey costs, metric calculations, and gain plan preparation time.
For a full breakdown of which projects are currently exempt, see the Exempt Projects resource.
Which Developers Qualify for the BNG Exemption in July 2026?
The July 2026 reforms create several qualifying routes for exemption. A development is expected to be exempt from mandatory BNG if it meets any of the following criteria: [1][6][8]
| Exemption Category | Condition | Notes |
|---|---|---|
| Area-based (new) | Total site area 0.2 ha or less | Priority habitats remain a constraint |
| Temporary permission | Planning permission for 5 years or less | New category from July 2026 |
| Biodiversity-led development | Primary objective is habitat creation or conservation | e.g. habitat creation schemes |
| Amenity enhancement | Parks, playing fields, public gardens | Excludes professional stadiums; excludes schemes within wider residential/mixed-use development |
| Householder applications | Already exempt under existing rules | No change |
| Permitted development | Already exempt under existing rules | No change |
Removed from July 2026: The self-build and custom-build exemption will be abolished. Developers who previously relied on this route for small residential schemes will need to assess whether their site qualifies under the new 0.2 ha area-based threshold instead. [2]
For guidance on whether your specific project is subject to BNG rules, the BNG for Small Development Projects guide covers common edge cases.
How Much Does Biodiversity Net Gain Cost for Developers?
BNG costs fall into two broad categories: assessment and compliance costs, and unit or credit purchase costs.
Assessment costs typically include:
- Baseline habitat survey and metric calculation (varies by site size and complexity)
- Biodiversity Gain Plan preparation
- Monitoring reports across the 30-year management period
Unit and credit costs depend on the delivery route chosen. Off-site habitat units purchased from registered habitat banks vary in price depending on habitat type, condition, and geographic location. Statutory biodiversity credits, available from Natural England as a last resort, are priced at a significant premium to incentivise on-site and off-site delivery first. For current pricing benchmarks, see this guide to the cost of biodiversity units and statutory credits.
The 0.2 ha exemption will remove assessment costs entirely for qualifying sites, which is a material saving for small developers where ecology fees can represent a disproportionate share of pre-application expenditure.
Biodiversity Net Gain Off-Site vs On-Site Requirements: What Changes for Minor Development?
Under the existing BNG hierarchy, on-site delivery is preferred, off-site units come second, and statutory credits are the last resort. For minor development, the April 2026 Government response confirms that off-site gains will be treated as equal in rank to on-site gains. [6][8]
This is a practical acknowledgement that many minor development sites, particularly urban infill plots, have limited space or ecological opportunity to deliver meaningful habitat on site. Equalising the hierarchy removes a barrier that previously required developers to demonstrate on-site delivery was not feasible before purchasing off-site units.
Practical implications:
- Ecologists preparing Biodiversity Gain Plans for minor development can now recommend off-site units without needing to justify why on-site delivery was rejected.
- Habitat bank operators may see increased demand from the minor development sector.
- Local planning authorities will need to update their BNG validation checklists to reflect the revised hierarchy.
For a detailed comparison of delivery routes, see Biodiversity Net Gain: Off-site or On-site Delivery?
Biodiversity Net Gain vs Habitat Banking: What Is the Difference?
Biodiversity Net Gain is the legal obligation placed on developers. Habitat banking is one mechanism for meeting that obligation off site.
A habitat bank is a parcel of land where a landowner or operator creates, restores, or enhances habitats in advance of development demand. The resulting biodiversity units are registered on the Natural England biodiversity gain site register and sold to developers who need off-site units to complete their BNG calculation. This is distinct from land banking, which involves holding land without active habitat management. For a full comparison, see BNG Off-site: Land Banking vs. Habitat Banking.
The July 2026 reforms, by equalising off-site and on-site delivery for minor development, are likely to increase the commercial case for habitat bank operators targeting the smaller-sites market.
Biodiversity Net Gain Timeline and Deadlines for Compliance in 2026
The key dates developers and planners need to track are:
- 15 April 2026: Government published its formal response to DEFRA's May 2025 consultation on BNG for minor, medium, and brownfield development. [6]
- 10 June 2026: Separate brownfield consultation (covering sites up to 2.5 hectares) closed.
- 31 July 2026 (expected): New 0.2 ha area-based exemption takes effect; self-build/custom-build exemption removed; temporary permission exemption introduced; minor development hierarchy amended. All subject to parliamentary scheduling. [1][5]
- 2 November 2026: BNG mandatory for Nationally Significant Infrastructure Projects (NSIPs) for applications submitted on or after this date. No retrospective application.
Common mistake: Assuming the brownfield reforms are already in force. The brownfield consultation only closed in June 2026; secondary legislation has not yet been introduced. Developers with brownfield sites above 0.2 ha should continue to comply with existing BNG requirements until further notice.
How to Apply for a BNG Exemption as a Developer
There is no separate formal application process for BNG exemptions. Instead, the exemption is declared at the planning application stage.
Steps for claiming the 0.2 ha exemption (from July 2026):
- Confirm the total site area is 0.2 ha or less using the red line boundary on the application drawings.
- Commission a desktop review or walkover survey to confirm no priority habitats are present on or directly affected by the site.
- Complete the BNG exemption declaration on the relevant planning application form (the Planning Portal forms are expected to be updated ahead of the July 2026 commencement date).
- The local planning authority validates the exemption claim as part of the application.
- Retain records in case of any post-decision query.
If priority habitats are identified, the site does not qualify for the area-based exemption and a full BNG assessment will be required.
Common Mistakes Developers Make with BNG Compliance
Even experienced development teams make avoidable errors with BNG. The most frequent issues include:
- Assuming exemption without checking priority habitats. A site under 0.2 ha is not automatically exempt if it contains or borders priority habitat.
- Starting on site before the Biodiversity Gain Plan is approved. The gain plan must be approved by the LPA before development commences, not just submitted.
- Underestimating the 30-year monitoring obligation. Management and monitoring costs over three decades can exceed the initial unit purchase price on some sites.
- Confusing the de minimis rule with the new area-based exemption. These are separate tests. The de minimis rule relates to the area of habitat affected; the new 0.2 ha exemption relates to total site area.
- Failing to register off-site habitat agreements. Off-site units must be registered on the Natural England biodiversity gain site register before they can be used in a gain plan.
For a broader checklist of compliance considerations, see 8 biodiversity net gain points on planning your project.
What Happens If You Don't Meet Biodiversity Net Gain Targets?
Failure to meet BNG requirements has direct planning consequences. A planning authority cannot grant permission for a development that does not demonstrate compliance with the mandatory 10% net gain requirement, unless the site qualifies for an exemption.
If a development proceeds without an approved Biodiversity Gain Plan where one is required, this constitutes a breach of planning condition. Enforcement action, stop notices, and retrospective compliance requirements are all possible outcomes. Where off-site units or statutory credits were purchased but monitoring obligations are not met over the 30-year period, the responsible party (typically secured by legal agreement) remains liable.
Conclusion: Actionable Steps for Developers and Consultants in 2026
The Biodiversity Net Gain BNG reforms July 2026 represent the most significant recalibration of the BNG framework since mandatory requirements came into force. The 0.2 hectare exemption for developers will reduce the compliance burden on a large proportion of smaller residential schemes, but it does not remove the need for careful site assessment, particularly where priority habitats are present.
Practical next steps:
- Audit your current pipeline against the 0.2 ha threshold and flag any sites that may qualify for exemption from July 2026.
- For sites that remain subject to BNG, review whether the revised minor development hierarchy (equalising off-site and on-site gains) changes your preferred delivery route.
- Monitor parliamentary progress on the secondary legislation: the 31 July 2026 date is subject to scheduling and could shift.
- If your pipeline includes brownfield sites above 0.2 ha, watch for the outcome of the brownfield consultation that closed 10 June 2026.
- For NSIP projects, confirm whether your application will be submitted before or after 2 November 2026, as this determines whether BNG applies.
- Engage a qualified ecologist early to confirm exemption status and, where BNG applies, to produce a robust metric assessment and gain plan.
The reforms signal a Government intent to reduce friction for small developers while maintaining ecological ambition for larger and more sensitive sites. Getting ahead of the changes now will avoid delays once the legislation is in force.
Frequently Asked Questions
What is the 0.2 hectare BNG exemption and when does it start?
The 0.2 hectare exemption is a new area-based threshold that will exempt developments with a total site area of 0.2 ha or less from mandatory BNG. It is expected to take effect by 31 July 2026, subject to parliamentary scheduling. Priority habitats on the site remain a constraint. [6]
Does the 0.2 ha exemption apply to commercial as well as residential development?
Yes. The exemption applies across all development types, not just residential. However, the estimated 50% reduction in BNG-affected permissions is based on residential planning data. [6]
Will self-build developers still be exempt from BNG after July 2026?
No. The existing self-build and custom-build BNG exemption will be removed from 31 July 2026. Self-build projects on sites of 0.2 ha or less may qualify under the new area-based exemption instead. [2]
What is the BNG requirement for temporary planning permissions?
From July 2026, planning permissions granted for a period of five years or less will be exempt from mandatory BNG requirements. This is a new exemption category introduced as part of the reform package. [1]
Does BNG apply to Nationally Significant Infrastructure Projects in 2026?
BNG becomes mandatory for NSIPs for applications submitted on or after 2 November 2026. There is no retrospective effect: NSIP applications submitted before that date are not subject to mandatory BNG. [6]
What happens to the biodiversity gain hierarchy for minor development?
Under the July 2026 reforms, off-site gains will rank equal to on-site gains for minor development. Previously, developers had to demonstrate on-site delivery was not feasible before using off-site units. This change removes that requirement for minor schemes. [8]
Is a BNG assessment still needed if a site qualifies for the 0.2 ha exemption?
A full statutory metric assessment and Biodiversity Gain Plan will not be required for exempt sites. However, a desktop review or walkover survey to confirm the absence of priority habitats is still advisable to support the exemption declaration on the planning application form.
What is the difference between statutory biodiversity credits and off-site habitat units?
Off-site habitat units are created by private landowners and sold through habitat banks registered with Natural England. Statutory biodiversity credits are purchased directly from Natural England and are priced at a premium to encourage on-site and off-site delivery first. For current pricing, see the guide to biodiversity credits for developers.
References
[1] Key Changes Confirmed To Biodiversity Net Gain – https://www.cla.org.uk/news/key-changes-confirmed-to-biodiversity-net-gain/
[2] Biodiversity Net Gain Changes 2026 – https://www.biodiverseconsulting.co.uk/post/biodiversity-net-gain-changes-2026
[3] Biodiversity Net Gain Consultation Latest News – https://www.nfuonline.com/news/biodiversity-net-gain-consultation-latest-news/
[5] Government Takes Step To Simplify Biodiversity Net Gain – https://www.fsp-law.com/government-takes-step-to-simplify-biodiversity-net-gain/
[6] Government Response And Summary Of Responses – https://www.gov.uk/government/consultations/improving-the-implementation-of-biodiversity-net-gain-for-minor-medium-and-brownfield-development/outcome/government-response-and-summary-of-responses
[7] BNG No More Loopholes – https://www.the-ies.org/system/files/paragraphs/cw_file/2026-02/BNG_no_more_loopholes.pdf
[8] BNG Simplified: Smaller Sites, Fewer Hurdles – https://lichfields.uk/blog/2026/april/17/bng-simplified-smaller-sites-fewer-hurdles
