BNG Temporary Development Exemption August 2026: The 5 Year Rule Explained

Last updated: 12 August 2026

Quick Answer: The BNG temporary development exemption August 2026 5 year rule, introduced under SI 2026 No. 790 and in force from 6 August 2026, exempts planning permissions that restrict development to five years or less from mandatory biodiversity net gain requirements. The entire development must be temporary in nature, no priority habitats can be present on site, and developers must retain documentary evidence to demonstrate compliance throughout the permission period.

Key Takeaways

• SI 2026 No. 790 came into force on 6 August 2026, creating a formal exemption for temporary developments with permissions of five years or less.
• Only applications made on or after 6 August 2026 can rely on this exemption, earlier permissions are not covered retrospectively.
• The whole development must be temporary; mixed schemes combining permanent and temporary elements do not qualify.
• Priority habitats on site disqualify a development from the exemption, regardless of the permission duration.
• Qualifying use cases include meanwhile-use sites, temporary logistics yards, pop-up retail, construction compounds, and phased infrastructure lay-down areas.
• Developers must retain evidence of the temporary nature of the permission and any reinstatement obligations throughout and after the development period.
• The exemption does not remove the need to comply with planning conditions relating to reinstatement or ecological protection.
• Anti-avoidance provisions prevent developers from splitting or sequencing permissions to circumvent the five-year threshold.
• Defra's July 2026 amendments and accompanying guidance clarify how local planning authorities should verify and record exempt applications.
• After the five-year period ends, if any permanent development is sought, full BNG obligations apply to any new application.

What Is the BNG Temporary Development Exemption August 2026?

The BNG temporary development exemption August 2026 is a statutory carve-out from mandatory biodiversity net gain obligations for development permissions that are time-limited to five years or less. It was created by The Biodiversity Gain (Exemptions) (Amendment) Regulations 2026, cited as SI 2026 No. 790, and took effect on 6 August 2026 [9].

Under the standard BNG framework, most new planning permissions in England must demonstrate a minimum 10% net gain in biodiversity before development can begin. The temporary exemption recognises that short-duration development, where land is returned to its prior condition after use, poses a materially different ecological risk profile than permanent development. Defra's April 2026 blog post signalled the policy intent ahead of the formal regulations, noting that proportionality was a key driver for the amendments [10].

For a full overview of how mandatory BNG works across all development types, see the Biodiversity Net Gain guidance.

How Does the 5 Year Rule Work for BNG Exemptions?

The five-year rule means that a planning permission must, on its face, restrict all development activity on the site to a period of five years or fewer from the date the permission is granted. The restriction must appear as a condition on the permission itself, it cannot be a developer's informal intention or a statement in a planning statement [2].

Key mechanics of the rule:

• The five-year clock runs from the date of grant, not the date development commences.
• The permission must include a condition requiring cessation of all development use and reinstatement of the land by the end of the five-year period.
• A permission that allows development to commence within five years but does not restrict its duration does not qualify, that is the standard commencement condition, not a temporary permission.
• Where a permission is extended or varied under section 73, the clock resets and the new permission must independently satisfy the five-year test [7].

Which Developments Qualify for the BNG August 2026 Exemption?

To qualify under the BNG temporary development exemption August 2026 5 year rule, a development must satisfy three cumulative criteria set out in SI 2026 No. 790 [9]:

1. The permission duration is five years or less, with a reinstatement condition attached.
2. The entire development is temporary, no permanent structures, infrastructure, or land-use changes are proposed or permitted.
3. No priority habitats are present on the application site at the time of the application.

Qualifying examples include:

• Meanwhile-use sites: Vacant urban land used temporarily for community gardens, markets, or event spaces pending permanent development.
• Temporary logistics yards: Short-term HGV consolidation centres or storage compounds supporting nearby construction projects.
• Pop-up retail and hospitality: Seasonal or event-driven retail structures, food and drink pavilions, or festival infrastructure.
• Construction compounds: Welfare facilities, site offices, material storage, and plant compounds that will be removed on completion of the main works.
• Phased infrastructure lay-down areas: Temporary land take for pipeline, cable, or road construction where land is reinstated to pre-development condition after use.

What does not qualify:

• Any scheme that includes a permanent element, even if the majority of the development is temporary.
• Sites where a desk study, Phase 1 habitat survey, or local authority records identify priority habitat.
• Applications made before 6 August 2026, the regulations are not retrospective [1].

For a broader look at which project types sit outside BNG requirements, the Exempt Projects page provides a useful reference.

The Priority Habitat Carve-Out: A Critical Disqualifier

The priority habitat carve-out is one of the most consequential aspects of the exemption. If the application site contains any priority habitat as defined under Section 41 of the Natural Environment and Rural Communities Act 2006, the temporary development exemption does not apply, regardless of how short the permission period is [2].

This matters in practice because:

• A temporary logistics yard proposed on land with semi-improved grassland or hedgerows meeting priority habitat criteria will require full BNG compliance.
• Developers must commission at minimum a Phase 1 habitat survey before relying on the exemption, to confirm the absence of priority habitats.
• Wealden District Council's guidance, published in summer 2026, advises applicants to submit a brief habitat confirmation note alongside the application to assist officers in verifying exempt status, an approach other LPAs are expected to follow.

Decision rule: If there is any doubt about whether priority habitat is present, commission a habitat survey before submitting. Relying on the exemption without evidence exposes the developer to enforcement risk if an LPA later disputes the classification.

What Evidence Must Developers Retain?

Developers relying on the BNG temporary development exemption August 2026 5 year rule must retain a specific evidence package throughout the permission period and for a reasonable period after reinstatement [9] [2].

Minimum evidence requirements:

Savills commentary from August 2026 notes that some LPAs are already requesting this evidence bundle as a pre-commencement condition, even where the exemption applies, to ensure an audit trail is available if the permission is later challenged or extended.

How Does the Exemption Interact with Planning Conditions?

The temporary development exemption removes the mandatory BNG obligation, it does not remove all ecological planning conditions. Developers should expect LPAs to attach conditions covering:

• Reinstatement timescales and methods.
• Restrictions on vegetation clearance during bird nesting seasons.
• Limitations on lighting and noise where bat foraging corridors are nearby.
• Requirements to avoid soil compaction in areas adjacent to trees subject to Tree Preservation Orders.

Lexology analysis published in August 2026 flags that some LPAs are attaching "ecological management notes" to exempt temporary permissions as a matter of policy, even where they cannot require a full Biodiversity Metric calculation. Developers should review draft conditions carefully and, where conditions appear to replicate BNG obligations by another name, seek clarification from the LPA before commencement.

For context on how BNG conditions typically operate in permanent schemes, the Secondary BNG Legislation Summary provides useful background.

What Happens After the 5 Year Exemption Ends?

When the five-year permission period expires, two outcomes are possible:

1. Reinstatement as required: The developer removes all temporary development, reinstates the land to its pre-development condition, and the exemption has been used correctly. No further BNG obligation arises from that temporary permission.
2. Application for permanent or further temporary permission: Any new application for the same site, whether permanent development or a further temporary use, is treated as a fresh application and assessed against BNG requirements in full at that point in time [5].

Anti-avoidance provisions in SI 2026 No. 790 specifically address sequential temporary permissions. Where an LPA has reasonable grounds to believe that a series of temporary permissions is being used to avoid permanent BNG obligations, it may treat the cumulative development as a single scheme and require BNG compliance accordingly [9]. Developers planning phased projects should take legal advice before structuring permissions as sequential five-year tranches.

Can the BNG Temporary Exemption Be Extended Beyond 5 Years?

No. The five-year threshold is a hard limit in SI 2026 No. 790. A permission of five years and one day does not qualify [9].

If a developer needs more time, the options are:

• Apply for a new temporary permission (subject to anti-avoidance scrutiny if the use is continuous).
• Apply for permanent permission with full BNG compliance.
• Apply under section 73 to vary a condition, but the varied permission must independently satisfy the five-year test, and the anti-avoidance provisions will apply if the LPA considers the variation an attempt to extend a de facto permanent use.

There is no mechanism in the current regulations to apply for an extension of the exemption period itself.

How Much Does the BNG Temporary Exemption Cost?

The exemption itself carries no application fee beyond the standard planning fee for the temporary permission. However, developers should budget for:

• Phase 1 habitat survey: Typically £500 to £2,500 depending on site size and complexity, needed to confirm the absence of priority habitats.
• Reinstatement plan preparation: Variable, but a simple method statement for a construction compound may cost £300 to £1,000 in consultant time.
• Post-reinstatement survey: Similar range to the Phase 1 survey.

These costs are substantially lower than the cost of a full Biodiversity Net Gain Assessment and the associated habitat unit procurement for a permanent scheme. For reference on the cost of biodiversity units where BNG does apply, the Cost of Biodiversity Units and Statutory Credits guide is a useful comparator.

Common Mistakes with the BNG 5 Year Exemption

Understanding where developers go wrong helps avoid costly delays or enforcement action.

Mistake 1: Assuming any short-term permission qualifies. A permission that allows development to commence within three years but does not restrict the duration of use is not a temporary permission. The condition must cap the total duration of the use, not just the commencement date.

Mistake 2: Failing to survey for priority habitats. Relying on a desktop assumption that a brownfield or hardstanding site contains no priority habitat is risky. Ruderal vegetation, standing water, and boundary features can all qualify.

Mistake 3: Including permanent elements in the scheme. A temporary logistics yard with a permanent access road does not qualify. The entire development must be temporary.

Mistake 4: Ignoring anti-avoidance risk on sequential permissions. Developers who have already obtained one temporary permission for a site and are seeking a second should take legal advice before submitting, particularly where the use has been continuous.

Mistake 5: Treating the exemption as removing all ecological obligations. LPAs retain full discretion to attach ecological conditions. The exemption removes the mandatory BNG metric and habitat management plan, it does not create an ecology-free permission.

For broader planning strategy on BNG, the 8 Biodiversity Net Gain Points on Planning Your Project guide covers the wider decision framework.

Interactive Tool: BNG Temporary Exemption Eligibility Checker

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function checkEligibility(){
var q1=document.getElementById(‘q1’).value,q2=document.getElementById(‘q2’).value,q3=document.getElementById(‘q3’).value,q4=document.getElementById(‘q4’).value,r=document.getElementById(‘cg-result’);
if(!q1||!q2||!q3||!q4){r.className=’cg-result cg-warn’;r.style.display=’block’;r.innerHTML=’Please answer all four questions.’;return;}
if(q1===’no’){r.className=’cg-result cg-fail’;r.style.display=’block’;r.innerHTML=’Not eligible. The exemption only applies to applications made on or after 6 August 2026. Full BNG obligations apply.’;}
else if(q2===’no’){r.className=’cg-result cg-fail’;r.style.display=’block’;r.innerHTML=’Not eligible. The permission must restrict use to 5 years or fewer with a reinstatement condition on the face of the permission.’;}
else if(q3===’no’){r.className=’cg-result cg-fail’;r.style.display=’block’;r.innerHTML=’Not eligible. Mixed schemes with permanent elements do not qualify. Full BNG compliance is required.’;}
else if(q4===’no’){r.className=’cg-result cg-fail’;r.style.display=’block’;r.innerHTML=’Not eligible. Priority habitats on site disqualify the exemption regardless of permission duration.’;}
else if(q4===’unsure’){r.className=’cg-result cg-warn’;r.style.display=’block’;r.innerHTML=’Survey required before proceeding. Commission a Phase 1 habitat survey to confirm no priority habitats are present before relying on the exemption.’;}
else{r.className=’cg-result cg-pass’;r.style.display=’block’;r.innerHTML=’Likely eligible for the BNG temporary development exemption under SI 2026 No. 790. Retain your habitat survey, reinstatement plan, and permission documentation throughout the development period.’;}
}

FAQ

Q: Does the BNG temporary development exemption August 2026 apply to permitted development rights?
A: No. The exemption under SI 2026 No. 790 applies to planning permissions, not to development carried out under permitted development rights. Permitted development rights have their own separate BNG framework and exemption criteria [2].

Q: Can a construction compound on a permanent development site use the temporary exemption?
A: Yes, provided the compound itself is the subject of a separate temporary planning permission of five years or less, the site contains no priority habitats, and the compound is fully reinstated at the end of the permission. If the compound is covered by the same permission as the permanent development, it does not qualify [9].

Q: What happens if a developer fails to reinstate the land at the end of the five-year period?
A: Failure to reinstate in accordance with the planning condition is an enforcement matter for the LPA. It does not retrospectively trigger BNG obligations for the expired permission, but the LPA can take enforcement action and any subsequent application for the site will require full BNG assessment [5].

Q: Does the exemption apply in Wales, Scotland, or Northern Ireland?
A: No. SI 2026 No. 790 applies in England only. BNG policy in Wales, Scotland, and Northern Ireland is governed by separate devolved legislation and does not currently include an equivalent temporary development exemption [2].

Q: Is a pop-up retail structure on a car park likely to qualify?
A: Probably yes, if the permission is for five years or less, the car park surface is not a priority habitat, and the structure is fully removable. However, if the car park contains any grassland, standing water, or boundary features meeting priority habitat criteria, a survey is needed before relying on the exemption.

Q: Where can developers find the official list of exempt development categories?
A: Defra's guidance on biodiversity net gain exempt developments, available on GOV.UK, is the primary reference [2]. SI 2026 No. 790 is the enabling legislation [9].

Conclusion

The BNG temporary development exemption August 2026 5 year rule offers a genuinely useful concession for developers working with short-duration schemes. It removes a disproportionate compliance burden from meanwhile uses, construction compounds, and other temporary land uses that pose low long-term ecological risk, provided the qualifying criteria are met in full.

Actionable next steps for developers and planners:

1. Confirm the application date is on or after 6 August 2026 before relying on the exemption.
2. Commission a Phase 1 habitat survey to rule out priority habitats before submission.
3. Ensure the planning permission includes a condition capping the duration of use at five years or fewer, with an explicit reinstatement requirement.
4. Build the evidence file from day one: habitat survey, pre-commencement photographs, reinstatement plan, and post-reinstatement confirmation.
5. Take legal advice before structuring any scheme as sequential temporary permissions to avoid triggering anti-avoidance provisions.
6. Review all draft planning conditions carefully, the exemption removes mandatory BNG, but LPAs retain discretion to attach ecological conditions.

For projects that do not qualify for the temporary exemption, the Guidance for Developers section and the How to Achieve 10% Biodiversity Net Gain guide provide a clear route through full BNG compliance.

References

[1] New BNG Rules and Exemptions Apply From The 6th August 2026 – https://www.tunley-environmental.com/en/insights/new-bng-rules-and-exemptions-apply-from-the-6th-august-2026

[2] Biodiversity Net Gain Exempt Developments – https://www.gov.uk/guidance/biodiversity-net-gain-exempt-developments

[5] Biodiversity Net Gain – https://www.gov.uk/guidance/biodiversity-net-gain

[7] BNG August 2026 Regulations Confirmed – https://the-ferals.co.uk/news/bng-august-2026-regulations-confirmed

[9] Uksiem 20260790 En 001 – https://www.legislation.gov.uk/uksi/2026/790/pdfs/uksiem_20260790_en_001.pdf

[10] Biodiversity Net Gain: What's Changing and What It Means for You – https://defraenvironment.blog.gov.uk/2026/04/20/biodiversity-net-gain-whats-changing-and-what-it-means-for-you/