BNG On-Site First Rule Relaxation August 2026: What Non-Major Developments Need to Know

Last updated: August 20, 2026

Quick Answer: From 6 August 2026, the BNG on-site first rule relaxation for non-major developments means that smaller schemes no longer need to demonstrate that on-site habitat creation is unachievable before using off-site biodiversity units. Developers of non-major projects can now treat on-site and off-site delivery as equal options from the outset. This change, introduced through the Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026, applies to planning applications submitted on or after 6 August 2026. [5][6]

Key Takeaways

• The BNG on-site first rule relaxation August 2026 applies exclusively to non-major developments; major projects must still exhaust on-site options before going off-site.
• Non-major sites with a red-line area of 0.2 hectares or below are now fully exempt from BNG, provided no on-site priority habitat is affected.
• Developers of qualifying non-major schemes can go straight to off-site registered biodiversity units without producing evidence that on-site delivery is not feasible.
• The self-build and custom-build dwelling exemption has been removed for applications submitted on or after 6 August 2026.
• A new exemption for time-limited planning permissions of five years or less has been introduced.
• The transitional cut-off is the application submission date, not the determination date, applications submitted before 6 August 2026 remain under the old rules.
• The hierarchy relaxation is expected to increase demand for off-site habitat units from non-major developers, with potential upward pressure on unit prices in areas where habitat bank supply is constrained.
• Three factors now determine a non-major scheme's BNG position: application date, red-line area, and presence of on-site priority habitat.

What Is the BNG On-Site First Rule and How Does It Work?

The BNG on-site first rule is the statutory hierarchy that governs how developers must sequence their biodiversity net gain delivery. Under the original framework introduced by the Environment Act 2021, developers were required to prioritise on-site habitat creation or enhancement first, then turn to registered off-site biodiversity units only if on-site delivery was not achievable, and finally use statutory biodiversity credits as a last resort. [5]

This hierarchy applied to all developments subject to mandatory BNG. For non-major schemes, this created a practical burden: applicants had to produce evidence, typically from an ecologist, demonstrating that on-site options had been genuinely considered and found insufficient before off-site units could be used. For a small infill housing site or a minor commercial scheme, that evidential requirement added cost and time disproportionate to the scale of development.

For a fuller overview of how on-site and off-site delivery interact under the standard framework, see this guide to biodiversity net gain off-site or on-site delivery.

BNG On-Site First Rule Relaxation August 2026: What Changed?

The core change is straightforward. For non-major development applications submitted on or after 6 August 2026, options 1 (on-site) and 2 (off-site registered units) now sit at the same level of the biodiversity gain hierarchy. Developers no longer need to evidence that on-site is not achievable before selecting off-site delivery. [5][6]

Defra's official blog confirmed on 14 July 2026 that minor sites above 0.2 ha that are not otherwise exempt "can choose to go straight to offsite in the first instance." [6] Updated GOV.UK guidance (last updated 18 August 2026) reinforces this, stating that applicants for small minor developments can choose off-site BNG without considering on-site first. [5]

What this means in practice:

• No requirement to submit an ecological justification for bypassing on-site delivery
• Faster pre-application conversations with local planning authorities
• Reduced ecology consultancy costs at the appraisal stage for non-major schemes
• Greater commercial flexibility in choosing the most cost-effective BNG route

The on-site first hierarchy remains fully intact for major development. That distinction is not incidental, it is the central design of the August 2026 amendment. [5][6]

Which Developments Qualify as Non-Major Under the New BNG Rules?

Non-major (or "minor") development is defined by reference to the Town and Country Planning (Development Management Procedure) (England) Order 2015. In residential terms, non-major means fewer than 10 dwellings, or a site area below 0.5 hectares where the number of dwellings is not specified. For commercial development, non-major means a floor space of less than 1,000 square metres or a site area below 1 hectare. [2][5]

Quick reference, non-major thresholds:

Major developments, including those above these thresholds, are not affected by the on-site first relaxation and must continue to follow the full hierarchy. [5][6]

The 0.2 Hectare Small-Site Exemption: Who Is Covered?

Non-major sites with a red-line area of 0.2 hectares or below are fully exempt from mandatory BNG, provided the application does not affect on-site priority habitat. This exemption applies to planning applications submitted on or after 6 August 2026. [7][5]

Industry commentary suggests this exemption could remove a significant proportion of small residential applications from the BNG regime entirely, including many urban infill plots, single-dwelling replacements, and small extensions. [1] For those sites, neither on-site nor off-site BNG delivery is required.

For non-major sites above 0.2 ha that are not otherwise exempt, the relaxed hierarchy applies: developers may go straight to off-site units. For more detail on how BNG applies to smaller schemes, see BNG for small development projects.

How Do Developers Calculate BNG Requirements After August 2026?

The 10% biodiversity net gain requirement itself has not changed. What has changed is how non-major developers can meet it. The Biodiversity Metric (currently version 4.0) still governs the calculation of baseline habitat units and the 10% uplift needed. [5]

The three-step check for non-major schemes submitted from 6 August 2026:

1. Application date, Was it submitted on or after 6 August 2026? If not, the old rules apply.
2. Red-line area, Is the site 0.2 ha or below with no priority habitat impact? If yes, BNG is exempt.
3. On-site priority habitat, Does the site contain or affect priority habitat? If yes, the exemption does not apply even below 0.2 ha.

If a non-major scheme clears these checks and BNG is required, the developer can now proceed directly to sourcing off-site registered units to cover the full 10% requirement, without any prior on-site assessment or justification. [5][6][1]

Developers unsure about their obligations can review the secondary BNG legislation summary for the broader regulatory context.

Can You Pay Into a BNG Fund Instead of Delivering On-Site Now?

Statutory biodiversity credits, the government-administered last resort, remain the third and final option in the hierarchy, unchanged by the August 2026 amendments. Developers cannot bypass registered off-site units and go straight to credits simply because the on-site first requirement has been relaxed. [5]

Credits remain significantly more expensive than market-rate off-site units and are intended as a fallback where neither on-site nor registered off-site delivery is possible. The August 2026 relaxation does not alter this position. For a comparison of unit and credit costs, see the guide to cost of biodiversity units and statutory credits.

Removal of the Self-Build Exemption: What Developers Must Know

One significant tightening within the August 2026 package is the removal of the self-build and custom-build dwelling exemption. Previously, self-build and custom-build projects were exempt from mandatory BNG. For applications submitted on or after 6 August 2026, that exemption no longer exists. [6][3]

Self-build applicants now need to assess whether another exemption applies, most commonly the 0.2 ha small-site exemption. A self-build plot of 0.2 ha or below with no priority habitat impact will qualify for the area-based exemption. A larger self-build plot will not, and BNG obligations apply in full. [7][6]

This change has caught some applicants off-guard, particularly those who had structured their project timeline around the former self-build exemption. The transitional cut-off is firm: the application submission date determines which regime applies.

Market Impact: What the On-Site First Relaxation Means for Habitat Unit Demand

The BNG on-site first rule relaxation August 2026 for non-major developments is the aspect of the package with the most direct market consequences. By removing the evidential barrier to off-site delivery, the amendments are expected to channel a new cohort of smaller developers into the off-site habitat unit market.

Previously, many non-major developers attempted on-site delivery, even on constrained urban plots, to avoid the cost and complexity of sourcing registered units. The relaxation removes that procedural incentive. Developers who would have delivered marginal on-site habitat can now legitimately opt for off-site units instead.

Potential market effects:

• Increased demand for small unit parcels from habitat banks, particularly in areas with high concentrations of non-major residential development
• Upward price pressure on off-site units in local planning authority areas where habitat bank supply is limited
• Greater interest in off-site land banking versus habitat banking as landowners respond to demand signals
• Ecology consultancies may see reduced instruction volumes for on-site feasibility work on minor schemes, offset by increased demand for off-site unit procurement support

Foot Anstey's briefing on the August 2026 changes notes that the relaxation is specifically targeted at reducing disproportionate burdens on small developers, while retaining the environmental integrity of the BNG framework for larger schemes. [1]

Which Councils Are Affected by the August 2026 BNG Changes?

The August 2026 amendments apply across England. There is no local authority opt-out. Every local planning authority in England must apply the new rules to applications submitted on or after 6 August 2026. [5][6]

Local planning authorities that had developed detailed local validation checklists requiring on-site first evidence for minor schemes will need to update their requirements. Applicants should not assume that pre-August 2026 local guidance still reflects current requirements, the national regulatory change supersedes any local procedural requirements that were based on the old hierarchy.

Common Mistakes Developers Make With the BNG On-Site First Relaxation

Assuming the relaxation applies to all developments. It does not. Major developments must still follow the full on-site first hierarchy. Applying the relaxed approach to a major scheme risks a planning condition requiring retrospective on-site assessment. [5][6]

Ignoring the application submission date. The transitional rules are strict. A planning application submitted on 5 August 2026 falls under the old regime, even if determined after 6 August 2026. [4]

Overlooking priority habitat on small sites. The 0.2 ha exemption disappears if the site contains or affects priority habitat. An ecological walkover survey is still advisable before assuming exemption applies. [7]

Failing to register off-site units before discharge of condition. The relaxation removes the evidential barrier to using off-site units, but the units themselves must still be from a registered habitat bank and secured by a conservation covenant or s106 agreement before the biodiversity gain condition can be discharged. [5]

How Long Do Developers Have to Implement BNG After August 2026?

The 30-year management obligation for off-site habitat units is unchanged. Once a biodiversity gain plan is approved and units are allocated, the habitat management and monitoring obligations run for a minimum of 30 years from the date of the agreement. [5]

There is no shortened implementation window for non-major schemes under the August 2026 amendments. The relaxation affects how developers source their units, not how long those units must be maintained.

FAQ

Does the BNG on-site first rule relaxation apply to permitted development?
No. Permitted development rights are generally outside the mandatory BNG framework. The August 2026 relaxation applies to planning applications for non-major development that require planning permission and are subject to BNG obligations.

Can a non-major developer now use 100% off-site units to meet BNG?
Yes. For non-major applications submitted on or after 6 August 2026, the full 10% biodiversity net gain requirement can be met entirely through registered off-site units, with no requirement to deliver any on-site habitat enhancement. [5][6]

Does the 0.2 ha exemption apply to the red-line boundary or the developable area?
The exemption is based on the total red-line site area, not the net developable area or footprint. If the red-line boundary encompasses more than 0.2 ha, the exemption does not apply regardless of how much of the site is actually built on. [7]

Are commercial non-major developments affected by the on-site first relaxation?
Yes. The relaxation applies to all non-major development, not just residential. Commercial schemes below the major development thresholds can also go straight to off-site units for applications submitted from 6 August 2026. [5][6]

What happens to a self-build application submitted before 6 August 2026?
Self-build applications submitted before 6 August 2026 retain the benefit of the former self-build exemption under the transitional arrangements. The removal of the exemption only affects applications submitted on or after 6 August 2026. [6][4]

Does the time-limited permission exemption apply to phased developments?
The exemption covers planning permissions that are time-limited to five years or less. Phased developments with longer overall timescales are unlikely to qualify, but each phase should be assessed individually against the permission conditions. Legal advice is recommended for complex phased schemes. [6][3]

Conclusion

The BNG on-site first rule relaxation August 2026 for non-major developments is a targeted, practical adjustment that removes a procedural burden without weakening the 10% biodiversity net gain obligation itself. For developers, the immediate benefit is clear: no more ecology reports justifying why on-site delivery is not feasible before off-site units can be used. For ecology consultants, the shift redirects work from on-site feasibility assessments toward off-site unit procurement and habitat bank due diligence.

Actionable next steps for developers and consultants:

• Audit your pipeline for non-major applications not yet submitted and confirm whether the 0.2 ha exemption applies before incurring BNG costs.
• Update pre-application checklists to remove the on-site first evidential requirement for qualifying non-major schemes.
• Engage with registered habitat banks early to understand unit availability and pricing in your local authority area, given anticipated demand increases.
• Confirm the self-build status of any pending applications and assess whether an alternative exemption applies.
• For applications straddling the 6 August 2026 date, verify the submission date carefully before advising clients on which regime applies.

For further guidance on sourcing off-site units, see buy biodiversity units or explore the guidance for developers section.

References

[1] 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/

[2] planninggeek.co.uk – https://www.planninggeek.co.uk/planning/bng/

[3] Biodiversity Net Gain Changes 6 August 2026 Developer Exemptions What Every Developer Needs To Know – https://biodiversitysurveyors.com/blog/biodiversity-net-gain-changes-6-august-2026-developer-exemptions-what-every-developer-needs-to-know

[4] BNG Transitional Arrangements August 2026 Which Planning Applications Fall Under The Old Regime – https://biodiversitysurveyors.com/blog/bng-transitional-arrangements-august-2026-which-planning-applications-fall-under-the-old-regime

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

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

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

[8] Biodiversity Net Gain Whats 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/