BNG Transitional Arrangements August 2026: Which Planning Applications Fall Under the Old Regime

Last updated: August 13, 2026

Quick Answer: The 6 August 2026 BNG changes are not retroactive. Which regime applies to any given planning application depends primarily on when that application was submitted, not when it is determined. Applications made before 6 August 2026 continue under whichever BNG rules were in force at their submission date, and applications made before 12 February 2024 fall outside mandatory BNG entirely. Developers must check submission date, permission route, site size, and exemption category to confirm which regime governs their project.

Key Takeaways

• Applications submitted before 12 February 2024 are not subject to mandatory BNG at all, regardless of what happens after August 2026.
• Applications submitted on or after 12 February 2024 but before 6 August 2026 remain under the original 2024 BNG regime, not the revised post-August 2026 rules.
• The new 0.2-hectare small-site exemption and the new temporary development exemption only apply to applications made on or after 6 August 2026.
• The self-build/custom-build exemption is preserved for applications submitted before 6 August 2026 but removed for those submitted on or after that date.
• Section 73 variations linked to pre-12 February 2024 permissions remain outside mandatory BNG, even if determined years later.
• Several permission routes, including local development orders, neighbourhood development orders, and NSIPs, still sit outside BNG regardless of the August 2026 changes.
• From 6 August 2026, the biodiversity gain hierarchy for non-major development is relaxed: on-site and registered off-site gains are now equally preferred.
• Developers with pipeline applications should audit each project's submission date and permission type before assuming any new exemption applies.

What Are the BNG Transitional Arrangements August 2026 and Why Do They Matter?

The BNG transitional arrangements August 2026 determine which planning applications fall under the old regime and which must comply with the revised rules introduced by Defra's secondary legislation, which came into force on 6 August 2026. Defra published its explanation of the amendments in July 2026, confirming that the changes are prospective only [2].

This matters because the August 2026 package introduced several significant changes: a new exemption for sites no larger than 0.2 hectares, a new exemption for temporary permissions of up to five years, and the removal of the self-build/custom-build exemption. None of these changes apply to applications already in the system [2][4]. Developers who assume the new exemptions rescue a pipeline application submitted last year will be wrong, and that misreading could delay discharge of pre-commencement conditions.

For a broader grounding in how BNG works before examining the transitional rules, see Biodiversity Net Gain Explained.

Which Planning Applications Qualify for the Old BNG Regime After August 2026?

Three distinct cohorts of applications remain under pre-August 2026 rules, and each has a different legal basis.

Cohort 1: Pre-12 February 2024 applications. Any full planning application submitted before 12 February 2024 is entirely outside mandatory BNG. The transitional provisions in the original 2024 commencement regulations state that BNG only applies where the application was made on or after that date [5]. These projects remain under the pre-BNG regime in August 2026 and beyond, with no BNG obligation whatsoever.

Cohort 2: Small-site applications in the original transition window. Applications for small-site development submitted between 12 February 2024 and 2 April 2024 (the original extended transition period for small sites) remain outside mandatory BNG. Crucially, any subsequent section 73 variation to such a permission also stays outside BNG [5].

Cohort 3: Applications submitted 2 April 2024 to 5 August 2026. These applications are subject to mandatory BNG under the original 2024 regime. They cannot benefit from the new August 2026 exemptions, but they also do not lose any exemptions they already held at submission, such as the self-build exemption [7][9].

How Do I Know If My Planning Application Falls Under Transitional BNG Rules?

The test is straightforward: identify the date the planning application was formally validated (made), not the date of determination or the date any permission is implemented.

Work through this checklist:

1. Was the application made before 12 February 2024? If yes, no mandatory BNG applies.
2. Was it a small-site application made between 12 February and 2 April 2024? If yes, no mandatory BNG applies.
3. Was it made between 2 April 2024 and 5 August 2026? If yes, the original 2024 BNG regime applies.
4. Is it being made on or after 6 August 2026? If yes, the revised regime with new exemptions and the relaxed hierarchy applies.
5. What type of permission is it? Section 73 variations, LDOs, NDOs, NSIPs, and section 73A retrospective permissions have their own rules (see below).

Planning and ecology practitioners at Crossman Ecology and Foot Anstey both stress that developers must check all five factors, because getting one wrong can result in either unnecessary BNG expenditure or an unlawful commencement [4][10]. The secondary BNG legislation summary provides useful background on how the original regulations were structured.

How Are Section 73 Applications Treated Under the BNG Transitional Rules?

Section 73 variations are exempt from mandatory BNG where the original permission was either granted before 12 February 2024 or the application for that original permission was made before that date [5][11]. This exemption persists regardless of when the section 73 variation is submitted or determined, so a section 73 application lodged in 2026 or later to vary a 2022 permission remains outside BNG.

Section 73A retrospective permissions are also outside mandatory BNG commencement entirely, because BNG commencement regulations do not apply to them [5].

Common mistake: Some developers assume that because a section 73 variation introduces new development footprint, BNG must be assessed afresh. That is not the position under the transitional arrangements. The trigger is the original permission date, not the scope of the variation [5][10].

Edge case: Where a section 73 variation relates to a permission that was itself subject to BNG (i.e., the original application was made on or after 12 February 2024), the variation may also be within scope of BNG. Legal advice from Foot Anstey confirms that the link to the original permission date is the decisive factor [4].

Cut-Off Date Table: Which Regime Applies?

What Planning Applications Are Exempt from New BNG Rules in August 2026?

Several categories sit permanently outside mandatory BNG and are unaffected by the August 2026 changes. These include householder development, de minimis development affecting less than 25 m2 of habitat and 5 m of linear habitat (with no impact on priority habitat), development whose primary objective is to conserve or enhance biodiversity, and certain works to parks, playing fields, and public gardens [1][3].

Beyond those standing exemptions, the August 2026 package added two new exemptions that apply only to applications made on or after 6 August 2026 [2][4]:

• Small-site exemption: Development on a site no larger than 0.2 hectares, provided no on-site priority habitat is affected.
• Temporary development exemption: Development where planning permission is granted for a maximum of five years and the entire development is temporary, again with no priority habitat impact.

Applications submitted before 6 August 2026 cannot rely on either of these new exemptions, even if the development would qualify on size or temporary-use grounds [4][10]. For a full list of exempt project types, see the exempt projects guidance.

Do Applications Submitted Before August 2026 Use Old BNG Requirements for Calculations?

Yes. Applications submitted before 6 August 2026 that are within mandatory BNG scope use the Biodiversity Metric and procedural rules that were in force at their submission date. The August 2026 amendments do not alter the calculation methodology or the biodiversity gain plan requirements for those earlier applications [2][6].

This has a practical consequence for developers with applications currently awaiting determination: if a local planning authority requests updated BNG information, the applicant should provide it under the rules applicable at submission, not the revised August 2026 rules. Crossman Ecology notes that some LPAs may need reminding of this distinction when processing older applications [10].

For guidance on what a BNG assessment should contain under the original regime, see what is in a biodiversity net gain assessment.

How Long Do Transitional BNG Arrangements Last After August 2026?

There is no fixed sunset date for the transitional arrangements. An application submitted before 12 February 2024 remains outside mandatory BNG for the life of that permission, including any future section 73 variations linked to the original pre-2024 consent [5]. Similarly, an application submitted between 2 April 2024 and 5 August 2026 remains under the original 2024 BNG regime for as long as that permission is being implemented.

The transitional arrangements are not a temporary grace period; they are a permanent feature of how the legislation operates. The applicable regime is locked in at the point of application, and no subsequent change in law alters that [2][4].

What Is the Newly-Relaxed BNG Hierarchy for Non-Major Development?

Under the original 2024 BNG regime, the statutory biodiversity gain hierarchy strongly favoured on-site habitat creation. Off-site gains were only to be used where on-site delivery was not possible or practicable.

From 6 August 2026, for non-major development (broadly, minor applications), the hierarchy is relaxed so that on-site habitat creation and registered off-site biodiversity units are treated as equally preferred options [6][7]. Statutory biodiversity credits remain the last resort.

This change applies only to applications made on or after 6 August 2026. Minor development applications submitted before that date are assessed under the previous hierarchy, where on-site delivery was the default [6]. For developers planning new minor schemes, this opens up more flexibility in how the 10% net gain is achieved. See biodiversity net gain off-site or on-site delivery for a practical comparison of both approaches.

Practical Implications for Developers with Pipeline Applications

Developers carrying pipeline applications across the August 2026 boundary need to take three immediate steps.

First, audit every application by submission date. Build a simple register that records validation date, permission type, site area, and whether priority habitats are present. This determines which of the three regimes (pre-BNG, original 2024 BNG, revised 2026 BNG) applies to each project.

Second, do not assume new exemptions apply retrospectively. The most common error flagged by Foot Anstey and Crossman Ecology is developers assuming the 0.2-hectare exemption rescues a small-site application already in the system [4][10]. It does not.

Third, review section 73 strategies. If a project involves varying an older permission, confirm whether that original permission predates 12 February 2024. If it does, the variation sits outside BNG entirely, which may simplify delivery significantly.

For developers who need to comply with the original 2024 regime on pending applications, the guide to biodiversity credits for developers and the 8 biodiversity net gain points on planning your project remain directly relevant.

FAQ

Does the 6 August 2026 date refer to when an application is submitted or when it is determined?
It refers to when the application is made (submitted and validated), not when the local planning authority determines it. An application submitted on 5 August 2026 and determined in October 2026 falls under the pre-August 2026 rules [2][4].

Can a developer re-submit an application after 6 August 2026 to take advantage of the new 0.2-hectare exemption?
Yes, technically. If a developer withdraws a pending application and resubmits on or after 6 August 2026, the new submission date applies and the new exemptions are available, provided the site qualifies. However, this resets the determination clock and carries risk, so legal advice is essential before withdrawing.

Are outline planning permissions covered by BNG transitional arrangements?
Yes. Outline permissions follow the same rule: the date the outline application was made determines the applicable regime. Reserved matters applications are linked to the outline permission, so if the outline predates 12 February 2024, BNG does not apply to reserved matters either [5].

What happens to a pending application if the LPA has not yet requested a biodiversity gain plan?
The application remains under the regime in force at its submission date. The LPA should request a biodiversity gain plan under the rules applicable at that date, not the revised August 2026 rules [2][10].

Does the removal of the self-build exemption affect existing self-build permissions?
No. The self-build/custom-build exemption is preserved for applications submitted before 6 August 2026. Only new self-build applications submitted on or after 6 August 2026 must comply with mandatory BNG [7][9].

Are NSIPs and nationally significant infrastructure projects affected by the August 2026 changes?
BNG commencement regulations do not currently cover NSIPs, so they remain outside mandatory BNG regardless of the August 2026 amendments [5][6].

Conclusion

The BNG transitional arrangements August 2026 establish a clear but multi-layered framework for determining which planning applications fall under the old regime. The decisive factor is almost always the date the application was made, not the date of determination, implementation, or any subsequent variation. Applications predating 12 February 2024 carry no BNG obligation; those submitted between April 2024 and 5 August 2026 remain under the original 2024 rules; and only new applications from 6 August 2026 onward benefit from the revised exemptions and relaxed hierarchy.

For developers, the practical priority is a dated audit of every pipeline project before assuming any new exemption applies. For section 73 strategies, the original permission date is the key variable. Getting this wrong wastes money on unnecessary BNG compliance or, worse, triggers an unlawful commencement.

Ready to confirm which BNG regime applies to your project? The team at Biodiversity Surveyors provides expert ecological assessments and biodiversity gain plans tailored to the correct applicable regime. Contact us to discuss your pipeline applications today.

References

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

[2] Biodiversity Net Gain Amendments And Transitional Arrangements Published – https://defraenvironment.blog.gov.uk/2026/07/14/biodiversity-net-gain-amendments-and-transitional-arrangements-published/

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

[4] New Biodiversity Net Gain Exemptions From August 2026 What Developers Need To Know – https://www.footanstey.com/our-insights/articles-news/new-biodiversity-net-gain-exemptions-from-august-2026-what-developers-need-to-know/

[5] BNG Final Regulations Laid Before Parliament – https://cieem.net/bng-final-regulations-laid-before-parliament/

[6] Defra Revises Englands Biodiversity Net Gain Regime Following Twin Consultations – https://www.osborneclarke.com/insights/defra-revises-englands-biodiversity-net-gain-regime-following-twin-consultations

[7] Biodiversity Net Gain Changes 6 August 2026 Developers New Exemptions Explained – https://biodiversitysurveyors.com/blog/biodiversity-net-gain-changes-6-august-2026-developers-new-exemptions-explained

[9] Biodiversity Net Gain 2026 What New Exemptions Mean Developers – https://www.linkedin.com/pulse/biodiversity-net-gain-2026-what-new-exemptions-mean-developers-vagee

[10] Biodiversity Net Gain Changes From 6 August 2026 What Developers Need To Know – https://www.crossmanecology.co.uk/biodiversity-net-gain-changes-from-6-august-2026-what-developers-need-to-know/

.bng-checker{font-family:Arial,sans-serif;max-width:560px;margin:2rem auto;border:1px solid #c8d8b0;border-radius:8px;padding:1.5rem;background:#f9fdf5}
.bng-checker h2{font-size:1.1rem;color:#2d5a1b;margin:0 0 1rem}
.bng-checker label{display:block;font-size:.9rem;color:#333;margin:.8rem 0 .3rem}
.bng-checker select{width:100%;padding:.45rem;border:1px solid #aac48a;border-radius:4px;font-size:.9rem;background:#fff}
.bng-checker button{margin-top:1.1rem;width:100%;padding:.6rem;background:#3a7d1e;color:#fff;border:none;border-radius:4px;font-size:.95rem;cursor:pointer}
.bng-checker button:hover{background:#2d5a1b}
.bng-result{margin-top:1rem;padding:.9rem;border-radius:5px;font-size:.9rem;display:none}
.bng-result.old{background:#fff8e1;border-left:4px solid #f0a500}
.bng-result.new{background:#e8f5e9;border-left:4px solid #3a7d1e}
.bng-result.none{background:#fce4e4;border-left:4px solid #c0392b}
.bng-result strong{display:block;margin-bottom:.4rem;font-size:.95rem}

function checkRegime(){
var d=document.getElementById(‘appDate’).value;
var p=document.getElementById(‘permType’).value;
var r=document.getElementById(‘bngResult’);
r.className=’bng-result’;r.style.display=’none’;
if(!d||!p){r.className=’bng-result none’;r.innerHTML=’Please select both options.‘;r.style.display=’block’;return;}
var msg=”,cls=”;
if(p===’ldo’){cls=’none’;msg=’Outside mandatory BNG.LDOs, NDOs, NSIPs and s73A permissions are not covered by BNG commencement regulations regardless of date.’;}
else if(p===’s73old’){cls=’none’;msg=’Outside mandatory BNG.Section 73 variations linked to a pre-12 February 2024 original permission are exempt from BNG, whenever the variation is submitted.’;}
else if(d===’pre2024′){cls=’none’;msg=’No mandatory BNG applies.Applications submitted before 12 February 2024 fall entirely outside the BNG regime.’;}
else if(d===’smalltrans’){cls=’none’;msg=’No mandatory BNG applies.Small-site applications in the original transition window (12 Feb, 2 Apr 2024) remain outside BNG, including future s73 variations.’;}
else if(d===’orig’){cls=’old’;msg=’Original 2024 BNG regime applies.New August 2026 exemptions do not apply. On-site gains are preferred. Assess under rules in force at your submission date.’;}
else if(d===’new’){cls=’new’;msg=’Revised August 2026 BNG regime applies.New 0.2 ha and temporary exemptions available if criteria met. On-site and registered off-site gains equally preferred for non-major development.’;}
r.className=’bng-result ‘+cls;r.innerHTML=msg;r.style.display=’block’;
}