BNG Small Site Exemption 0.2 Hectares August 2026: What Every Developer Needs to Know

Last updated: August 27, 2026

Quick Answer: From 6 August 2026, planning applications for developments on sites of 0.2 hectares or less are exempt from mandatory Biodiversity Net Gain (BNG) requirements in England, provided no on-site priority habitat is affected. This exemption applies only to applications submitted on or after that date. The 10% BNG requirement itself remains unchanged for all other developments.

Key Takeaways

• The BNG small site exemption 0.2 hectares August 2026 came into force on 6 August 2026 under the Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026.
• Sites at or below 0.2 ha are exempt from BNG only if no on-site priority habitat (Section 41 species) is affected.
• Temporary developments with planning permission granted for five years or less are now also exempt, provided the land is restored afterwards.
• The self-build and custom-build housing exemption has been removed; self-builders must now comply with standard BNG rules.
• Non-major developments gain greater flexibility: on-site habitat creation and registered off-site biodiversity gains are now treated with equal preference.
• The 10% BNG requirement is unchanged for all non-exempt developments.
• Applications submitted before 6 August 2026 cannot use the new exemptions, regardless of site size.
• Exempt sites remain subject to NPPF biodiversity protections and other environmental regulations.

What Is the BNG Small Site Exemption 0.2 Hectares?

The BNG small site exemption 0.2 hectares is a new area-based exemption that removes the mandatory requirement to deliver 10% Biodiversity Net Gain for planning applications where the entire site area within the red-line boundary is 0.2 hectares or less. It applies across all development types, residential, commercial, and mixed-use, not just housing [2][3].

The exemption was announced in December 2025 and formally introduced through the Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026, which came into force on 6 August 2026 [1]. Defra's April 2026 policy blog confirmed that the exemption applies only to applications made on or after that date [1].

The critical condition: if any on-site priority habitat (as listed under Section 41 of the Natural Environment and Rural Communities Act 2006) is present and affected by the development, the exemption does not apply and full BNG must be delivered [3].

What Changed on 6 August 2026, The Full Picture

As of 28 August 2026, the Regulations introduced four significant changes to BNG implementation in England [1][5]:

1. New 0.2 ha area-based exemption
All applications for sites at or below 0.2 ha, with no impact on on-site priority habitat, are exempt from BNG. This is the headline change and is expected to remove mandatory BNG from roughly half of all residential planning applications in England [2].

2. Temporary development exemption
Developments where planning permission is granted for five years or less, and where the land is restored to its former condition, are now exempt from BNG requirements [3][6].

3. Removal of the self-build exemption
The previously existing exemption for small-scale self-build and custom-build housing has been removed. Self-builders whose sites exceed 0.2 ha (or where priority habitat is present) must now comply with standard BNG obligations [1][5].

4. Greater flexibility for non-major schemes
For non-major developments that are not exempt, the hierarchy of BNG delivery has been relaxed. On-site habitat creation and registered off-site biodiversity gains are now treated with equal preference, removing the previous bias towards on-site delivery first. See our detailed guide on biodiversity net gain off-site or on-site delivery for how this affects your options.

Do I Qualify for the BNG Small Site Exemption 0.2 Hectares?

A development qualifies for the BNG small site exemption 0.2 hectares if it meets all three of the following criteria simultaneously [2][3]:

If any one of these criteria is not met, the exemption does not apply. For example, a 0.15 ha brownfield site with a fragment of Section 41 lowland meadow within the red line would still require full BNG compliance [3].

Common mistake: Some applicants assume the exemption applies to the developable area rather than the total red-line boundary. The threshold is the entire site area within the red-line, not just the footprint of built development [2][6].

For a full list of exempt project categories, see our exempt projects guidance.

What Counts as 0.2 Hectares for the BNG Exemption?

The 0.2 hectares threshold refers to the total land area enclosed within the red-line boundary of the planning application, not the built footprint, not the curtilage of a proposed building, and not any phased portion of a larger site [2][6].

To put this in practical terms:

• 0.2 ha equals 2,000 square metres, roughly the size of half a football pitch.
• A typical urban infill plot for one or two dwellings is often well below this threshold.
• A small commercial unit or conversion on a tight urban site will frequently qualify.

Edge case, site splitting: Local planning authorities and the Planning Inspectorate are expected to scrutinise applications where a larger site has been divided into sub-0.2 ha parcels to exploit the exemption. Artificial fragmentation of a single development to fall below the threshold is unlikely to be accepted [5][6].

Which Developments Do Not Qualify for the 0.2 Ha Exemption?

Several categories of development remain outside the exemption, even where the site is small [1][3][7]:

• Any site where on-site priority habitat (Section 41) is present and affected, regardless of size.
• Applications submitted before 6 August 2026.
• Self-build or custom-build schemes on sites above 0.2 ha (the self-build exemption has been removed).
• Developments forming part of a larger scheme where the combined site area exceeds 0.2 ha.
• Nationally Significant Infrastructure Projects (NSIPs), which operate under a separate BNG regime.

Agriculture and forestry operations already had separate exemptions under the original BNG framework and are unaffected by the August 2026 changes [3][9].

BNG Small Site Exemption vs Standard BNG Requirements

For developers weighing up whether they need to act, the table below summarises the key differences:

Even exempt sites are not a free pass on biodiversity. The NPPF requires all developments to avoid, mitigate, or compensate for harm to biodiversity where possible [7]. For a broader understanding of what a BNG assessment involves, see what is in a biodiversity net gain assessment.

How to Apply for the BNG Small Site Exemption

There is no separate formal application process for the exemption. Instead, developers evidence their eligibility as part of the standard planning application [2][6].

Practitioners advise the following steps to demonstrate compliance:

1. Confirm the red-line area is at or below 0.2 ha using an accurate site survey or OS data.
2. Commission a habitat survey (or robust desk study) using the UK Habitat Classification to confirm no Section 41 priority habitat is present or affected within the red line.
3. Include a short exemption statement in the planning application, referencing the Regulations and confirming both conditions are met.
4. Retain evidence of the habitat assessment in case the local planning authority requests clarification.

Local planning authorities, including Ashford Borough Council, have updated their BNG guidance to reflect the August 2026 changes and now confirm that qualifying applications received from 6 August 2026 are exempt [5]. For broader guidance on BNG for smaller projects, see our article on BNG for small development projects.

How Much Does the BNG Small Site Exemption Save?

The exemption removes the cost of BNG compliance entirely for qualifying sites. For context, the costs avoided typically include [4][8]:

• Biodiversity metric assessment: commonly £500,£2,000 for small sites (estimate based on typical ecology consultancy fees for minor schemes).
• Biodiversity Gain Plan preparation: additional professional fees.
• Off-site biodiversity unit purchases: costs vary significantly by habitat type and location; statutory credits can run to tens of thousands of pounds per unit.

For reference, our guide to the cost of biodiversity units and statutory credits sets out current market pricing in more detail.

The savings are meaningful for micro-developers and self-builders working on tight margins, which was a stated policy rationale behind the exemption [1].

What the Changes Mean for Self-Builders

Self-builders face a mixed outcome from the August 2026 changes. The removal of the dedicated self-build exemption means that self-build and custom-build projects no longer have a blanket exemption from BNG [1][5].

However, in practice, many self-build plots are small. A single-plot self-build on a site of 0.2 ha or less with no priority habitat will now qualify for the new area-based exemption, potentially leaving self-builders in a similar or better position than before, depending on their site.

Where a self-build site exceeds 0.2 ha, or where priority habitat is present, full BNG compliance is required. Self-builders in this position should seek early ecological advice to understand whether the Small Sites Metric (SSM) is appropriate for their scheme [4][10].

Common Mistakes with the BNG Small Site Exemption

Assuming brownfield means exempt. Brownfield sites can contain Section 41 priority habitats, for example, open mosaic habitats on previously developed land, which is itself a Section 41 habitat type. A desk study alone may not be sufficient; a site visit is often needed [2][6].

Measuring the wrong area. The threshold is the red-line boundary, not the development footprint. A 0.18 ha development footprint on a 0.25 ha site does not qualify [2].

Submitting before 6 August 2026. Applications submitted before the commencement date are ineligible, regardless of site size. There is no retrospective application of the exemption [1][3].

Ignoring NPPF obligations. Exempt sites still need to consider biodiversity in the design process. A planning authority can still refuse permission where significant harm to biodiversity cannot be adequately addressed [7].

Frequently Asked Questions

Does the 0.2 ha exemption apply to commercial as well as residential development?
Yes. The exemption applies to all development types where the red-line site area is 0.2 ha or less and no on-site priority habitat is affected. It is not restricted to housing [2][3].

Can I use the exemption if my site has a small patch of wildflower grassland?
Only if that grassland is not a Section 41 priority habitat. Lowland meadow, for example, is a Section 41 habitat; if it is present and affected, the exemption does not apply and full BNG must be delivered [3].

Is the 10% BNG target changing?
No. The 10% mandatory BNG requirement is unchanged. The August 2026 Regulations only affect which developments must comply, not the level of gain required from those that do [1][5].

My application was submitted in July 2026 for a 0.1 ha site. Am I exempt?
No. The exemption applies only to applications made on or after 6 August 2026. Applications submitted before that date must comply with BNG under the rules in force at the time of submission [1][3].

What happens to self-builders whose sites are above 0.2 ha?
They must comply with standard BNG requirements. The dedicated self-build exemption has been removed. A habitat survey and biodiversity metric assessment will be required, though the Small Sites Metric may simplify the process [1][4][10].

Are there other new exemptions introduced alongside the 0.2 ha threshold?
Yes. Temporary developments where planning permission is granted for five years or less (with land restoration) are now also exempt. A de minimis exemption also exists for developments impacting less than 25 m² of habitat and 5 m of linear habitat, where no priority habitat is affected [3][6].

Conclusion

The BNG small site exemption 0.2 hectares August 2026 is the most significant adjustment to BNG implementation since the regime was extended to small sites in April 2024. For micro-developers, infill builders, and many self-builders in England, it removes a genuine administrative and financial burden, provided the site conditions are met.

The key actions for developers and their advisers right now are:

• Confirm your red-line site area against the 0.2 ha threshold before submitting any application.
• Commission a habitat assessment to rule out Section 41 priority habitats, even on apparently bare or brownfield land.
• If you are a self-builder on a larger plot, seek early ecological advice to understand your BNG obligations under the new rules.
• For non-major schemes that do not qualify for the exemption, take advantage of the new equal-preference rule between on-site and off-site delivery to find the most cost-effective compliance route.

The 10% net gain requirement for non-exempt developments is here to stay. Sites that do not qualify for the exemption should engage a qualified ecologist early to avoid delays at the planning stage. For tailored advice on your specific project, contact our team or explore our guidance for developers.

References

[1] Biodiversity Net Gain Whats Changing And What It Means For You – defraenvironment.blog.gov.uk
[2] Bng Small Sites Exemption August 2026 What Uk Developers And Ecologists Must Know – Bng small sites exemption august 2026 what uk developers and ecologists must know
[3] Biodiversity Net Gain What Are The Exemptions – defraenvironment.blog.gov.uk
[4] Statutory Biodiversity Metric Including Small Sites – assets.publishing.service.gov.uk
[5] Bng Changes 6 August 2026 Small Site Exemption What Every Developer And Planner Must Know Now – Bng changes 6 august 2026 small site exemption what every developer and planner must know now
[6] Biodiversity Net Gain Changes 6 August 2026 Small Sites Exemption And New Rules For Developers – Biodiversity net gain changes 6 august 2026 small sites exemption and new rules for developers
[7] Key Changes Confirmed To Biodiversity Net Gain – cla.org.uk
[8] The Small Sites Metric And Offsite Bng – dentons.com
[9] Biodiversity Net Gain Extended To Small Sites – bali.org.uk
[10] Biodiversity Net Gain Now Applies To Small Developments – defraenvironment.blog.gov.uk

.bng-checker{font-family:Arial,sans-serif;max-width:480px;margin:2rem auto;border:2px solid #2d6a4f;border-radius:8px;padding:1.5rem;background:#f9fdf9}
.bng-checker h2{color:#2d6a4f;font-size:1.1rem;margin:0 0 1rem}
.bng-checker label{display:block;margin:.75rem 0 .25rem;font-size:.9rem;font-weight:600;color:#1b4332}
.bng-checker select,.bng-checker input{width:100%;padding:.5rem;border:1px solid #95d5b2;border-radius:4px;font-size:.9rem;box-sizing:border-box}
.bng-checker button{margin-top:1.2rem;width:100%;padding:.65rem;background:#2d6a4f;color:#fff;border:none;border-radius:5px;font-size:1rem;cursor:pointer}
.bng-checker button:hover{background:#1b4332}
.bng-result{margin-top:1rem;padding:.85rem;border-radius:5px;font-size:.9rem;display:none}
.bng-exempt{background:#d8f3dc;border-left:4px solid #2d6a4f;color:#1b4332}
.bng-required{background:#ffe8e8;border-left:4px solid #c0392b;color:#7b1c1c}
.bng-checker .note{font-size:.78rem;color:#555;margin-top:.5rem}

function checkExemption(){
var d=document.getElementById(‘appDate’).value;
var a=parseFloat(document.getElementById(‘siteArea’).value);
var p=document.getElementById(‘priorityHabitat’).value;
var re=document.getElementById(‘resultExempt’);
var rr=document.getElementById(‘resultRequired’);
var rt=document.getElementById(‘reasonText’);
re.style.display=’none’; rr.style.display=’none’;
if(!d||isNaN(a)||!p){alert(‘Please complete all fields.’);return;}
if(d===’before’){rt.textContent=’Applications submitted before 6 August 2026 are not eligible for the new exemptions.’;rr.style.display=’block’;return;}
if(a>0.2){rt.textContent=’Your site area exceeds 0.2 ha.’;rr.style.display=’block’;return;}
if(p===’yes’){rt.textContent=’On-site priority habitat is present and affected.’;rr.style.display=’block’;return;}
if(p===’unknown’){rt.textContent=’Priority habitat status is unconfirmed, a habitat survey is needed before you can rely on the exemption.’;rr.style.display=’block’;return;}
re.style.display=’block’;
}