BIODIVERSITY NET GAIN · OFF-SITE DELIVERY
Off-Site Biodiversity Units for Planning
A metric-led approach to suitable, registered and allocated off-site biodiversity gains.
For developments subject to mandatory BNG, the statutory metric may identify an off-site habitat-unit shortfall. Choosing a gain site takes more than matching a headline quantity. Habitat type, trading rules, location, legal securing and allocation must fit the permission.
ACP Consultants can review the unit shortfall, assess candidate off-site evidence and help align the ecological information with the Biodiversity Gain Plan. We do not claim to own a habitat bank or guarantee unit supply.
When Might a Development Use Off-Site Biodiversity Units?
First, confirm whether mandatory BNG applies to your permission. Exemptions and transitional rules can change the answer, especially for smaller or amended applications.
For major development, the biodiversity gain hierarchy gives priority to avoiding and reducing harm. Where compensation is needed, it generally prioritises on-site enhancement and creation before registered off-site gains. Statutory biodiversity credits remain the last option.
For non-major applications made on or after 6 August 2026, the hierarchy treats on-site enhancement, on-site creation and registered off-site biodiversity gain at the same level of preference. However, avoidance and mitigation still matter. Earlier applications and certain Section 73 permissions can follow the former hierarchy.
Off-site units may be worth exploring where the metric shows a shortfall, a design has limited on-site opportunities, or other land or a third-party gain site could deliver a technically suitable contribution.
Important: the 2026 exemption for qualifying sites of 0.2 hectares or below has additional conditions. For example, it does not apply if onsite priority habitat is affected. Do not assume that every small scheme needs or is exempt from BNG.
For a wider explanation of these rules, see BNG legislation and guidance.
How ACP Can Support Your Off-Site BNG Requirement
A credible off-site strategy begins with the development's own ecological evidence. ACP can review the following stages within an agreed consultancy scope.
1.Confirm the Unit Shortfall
Review the current metric and identify the remaining area-habitat, hedgerow or watercourse unit requirement. We also check relevant habitat-trading constraints.
2.Define the Off-Site Specification
Translate the shortfall into a clear request for the type, quantity and supporting evidence needed from potential gain sites. This helps prevent misleading like-for-like comparisons.
3.Review Candidate Options
Assess the ecological information supplied for a proposed gain site or provider. If no option has been identified, we can explain the evidence that should be requested and compared. We do not imply an ACP-owned habitat bank or guaranteed supply.
4.Check Delivery and Legal Evidence
Compare registration status, legal securing, metric inputs, management commitments and the Habitat Management and Monitoring Plan, as relevant. However, the appropriate legal advisers must review contract terms and legal interpretation.
5.Coordinate Allocation Information
Identify the gain-site reference, unit package and parties responsible for registering and allocating gains to your planning permission. We can support the technical information needed for that process.
6.Align the Biodiversity Gain Plan
Check that the registered allocation, metric and Biodiversity Gain Plan describe the same gains. We can also review and respond to BNG-related planning queries within the agreed commission.
Service boundary: ACP provides ecological and planning-focused consultancy. A provider's contractual promises, current stock and landowner commitments must be verified independently. No planning outcome is guaranteed.
What We Need to Review Your Off-Site Requirement
You do not need every document before contacting us. However, a few starting details help establish whether the shortfall is confirmed and which checks matter most.
Useful Starting Information
- Site address or location, with the red-line boundary if available.
- Planning application or permission reference and current project stage.
- Current layout and any proposed changes affecting habitat.
- Latest Statutory Biodiversity Metric workbook or Small Sites Metric where applicable.
- BNG assessment or ecology report, if already prepared.
- Known unit shortfall, ideally separated by habitat-unit category.
- Any candidate provider, gain-site reference or commercial offer.
- Planned dates for consent, allocation, Gain Plan submission and start on site.
If the shortfall is not established, the first step may be a BNG assessment and UKHab baseline survey or Statutory Biodiversity Metric calculation.
Do not have everything yet? Tell us what is known in your enquiry. We can identify the important gaps and discuss a proportionate first review. If a document review is needed, we can agree a suitable way to share the relevant files securely.
From Unit Shortfall to Biodiversity Gain Plan Evidence
The exact order can vary, because purchase, registration and allocation can overlap. However, a developer still needs a clear route from the metric shortfall to evidence that the off-site gains are allocated to the development.
1.Confirm the BNG Position
Check that the development is in scope and review the current planning stage, metric and BNG hierarchy.
2.Quantify the Remaining Shortfall
Confirm the relevant unit types and quantities that the development still needs to deliver.
3.Identify a Candidate Off-Site Solution
This may involve the developer’s own land outside the red-line boundary or units supplied by a third-party gain site.
4.Check Technical Suitability
Review the habitat requirement, metric trading rules, spatial treatment and strategic significance.
5.Check Delivery Evidence
Review gain-site registration, legal securing, management commitments and the supporting Habitat Management and Monitoring Plan where relevant.
6.Agree the Unit Package
The commercial arrangement should identify the number and type of units and the obligation to allocate those units to the development.
7.Record the Allocation
Next, record the relevant off-site biodiversity gains against the development on the Biodiversity Gain Sites Register.
8.Complete the BNG Evidence
The project metric and Biodiversity Gain Plan should identify the registered and allocated off-site gains used by the development.
Key point: the allocation must be recorded before the local planning authority can approve the Biodiversity Gain Plan.
Fallback: Statutory Biodiversity Credits
If the required BNG cannot be delivered through the applicable on-site and off-site routes, statutory biodiversity credits may be considered as the government last-resort mechanism.
They are not another name for private off-site biodiversity units.
Have You Already Identified an Off-Site Unit Shortfall?
Send us the current metric, site location and planning stage. If you already have a candidate provider or gain site, include those details and we can review the next steps.
How We Assess Whether Off-Site Units Are Suitable
A unit offered for sale is not automatically suitable for a development.
The project evidence and the gain-site evidence need to line up. The review should focus on the factors that determine whether the proposed off-site gain can actually support the BNG position.
Unit Type and Quantity
The candidate package must address the specific unit requirement shown by the development metric.
Area habitat, hedgerow and watercourse requirements should not be treated as a single interchangeable balance.
Metric Trading Rules
In addition, the proposed compensation must satisfy the applicable statutory metric trading rules.
For example, a simple total-unit comparison cannot establish whether the project meets habitat-specific replacement requirements.
Location and Spatial Treatment
The location of the gain site can affect how off-site gains are valued within the metric.
The exact spatial treatment depends on the relevant unit type and project geography.
Strategic Significance
The metric can also recognise whether proposed habitat delivery aligns with areas identified as strategically important for nature recovery.
This should be considered alongside the project’s local planning and nature-recovery context.
Gain-Site and Delivery Evidence
The gain site needs appropriate evidence for the habitat creation or enhancement being relied upon.
Depending on the stage, this can include the registered site information, metric evidence, legal agreement and Habitat Management and Monitoring Plan.
Allocation Availability
Finally, the provider must have the relevant gains available for allocation to the development.
The commercial arrangement should be clear about what will be allocated, when it will be recorded and what happens if the agreed allocation cannot be completed.
Practical point: a lower price, a nearby site or a large headline unit total does not, by itself, establish suitability.
Off-site unit evidence gates
Use these checkpoints to structure a review. They are not a legal eligibility ruling, a metric calculation or an enquiry submission.
- Confirm the metric shortfallArea, hedgerow and watercourse deficits recorded separately.
- Specify the habitat packageCheck habitat type, trading requirements and spatial treatment.
- Review the proposed gain siteCheck actual habitat baseline, delivery plan and professional evidence.
- Check legal securingConfirm the relevant S106 or conservation covenant and management period.
- Check registrationConfirm site reference and the gain-site register position.
- Check available gainsEnsure the proposed units are not already allocated.
- Record allocationAgree responsibilities and obtain the official allocation record.
- Align gain planCheck that the metric, site reference and gain plan agree.
Next step: collect the project evidence and discuss unresolved gates with the appropriate ecologist, land agent or legal adviser.
Why the Location of Off-Site Biodiversity Units Matters
Providers can deliver off-site biodiversity gains elsewhere in England. However, location still affects the metric.
Government guidance explains that the statutory biodiversity metric incentivises off-site gains closer to the development. More distant gains can receive a spatial penalty and therefore contribute fewer units to the development’s calculation.
Strategic significance can also affect the metric. This reflects whether the proposed habitat sits within an area identified as especially important for nature recovery.
As a result, a provider’s advertised number of units should not be treated as the number that will necessarily count towards your development.
Assess the Location Through the Metric
Therefore, test the candidate gain site within the development’s current metric evidence.
That allows the project team to understand:
- the spatial treatment that applies;
- whether the unit type is suitable;
- whether the proposal satisfies trading rules;
- whether strategic significance affects the calculation;
- whether a different location would provide a better technical fit.
Key point: assess location through the statutory metric and project evidence, not by mileage alone.
Registration, Allocation and Your Biodiversity Gain Plan
Gain-site registration and unit allocation are connected, but they are not the same step.
Gain-Site Registration
First, the landowner, leaseholder or an authorised applicant must register the site on the national Biodiversity Gain Sites Register.
The register shows where off-site habitat gains are being delivered and helps prevent the same gains being counted for more than one development.
However, the register is not a marketplace or buyer-seller matching service.
For the full registration process, see registering a Biodiversity Gain Site.
Allocation to Your Development
Next, once the parties agree the provider and unit package, they need to allocate the gains to the specific development.
The land manager can apply to record the allocation. A developer or other authorised person can also apply with the required landowner or leaseholder consent.
Government guidance allows registration and allocation to be completed together where appropriate.
Biodiversity Gain Plan Evidence
The applicant must record the off-site allocation before the local planning authority can approve the project’s Biodiversity Gain Plan.
Then, the Biodiversity Gain Plan should identify the gain-site reference and show how the allocated gains meet the development’s requirement.
For the full planning document, see our Biodiversity Gain Plan service.
Registration and Allocation at a Glance
| Stage | Main purpose | Developer-side question |
|---|---|---|
| Gain-site registration | Establish the off-site site and its secured habitat gains on the national register | Is the site registered, or is registration being progressed with the required evidence? |
| Allocation | Assign specified off-site gains to the individual development | Are the exact units available and recorded for this permission? |
| Biodiversity Gain Plan | Present the complete BNG delivery evidence to the LPA | Do the metric, allocation and BGP all refer to the same off-site gains? |
How Off-Site Biodiversity Gains Are Legally Secured
For statutory BNG, an appropriate legal agreement must secure the off-site gains and require maintenance for at least 30 years.
Government guidance identifies two legal agreement routes:
Section 106 Planning Obligation
The landowner enters a Section 106 agreement with the relevant local planning authority.
The LPA is responsible for enforcing the planning obligation.
Conservation Covenant
Alternatively, the landowner can enter a conservation covenant with an approved responsible body.
This can provide an alternative route for securing the long-term habitat commitment.
If you buy units from an off-site gain that is already legally secured and registered, the same habitat does not need to be secured again by the developer.
The legal agreement should work alongside the habitat delivery evidence, including the Habitat Management and Monitoring Plan where applicable.
For a fuller comparison of the two routes, see Conservation Covenant vs Section 106.
Important: ACP can review BNG documents and identify consistency issues within the agreed consultancy scope. Contract drafting and legal interpretation should be handled by an appropriately qualified legal adviser.
Off-Site Biodiversity Units and Statutory Biodiversity Credits Are Different
The terms are sometimes blurred in market language. Under the statutory BNG framework, they should be kept separate.
| Off-site biodiversity units | Statutory biodiversity credits | |
|---|---|---|
| What they are | Biodiversity gains delivered on a registered off-site gain site and allocated to a development | Government credits used as a last-resort BNG mechanism |
| Typical source | Landowner, habitat bank operator, broker, trading platform or other private-market provider | Natural England sells statutory credits on behalf of Defra |
| Project evidence | Gain-site registration, allocation and supporting metric/delivery evidence | LPA agreement to use credits and proof of statutory credit purchase |
| Pricing | Commercially agreed between buyer and seller | Government-published statutory credit prices |
| Metric treatment | Off-site spatial factors can affect the value of the gains to the development | The metric applies the statutory credit spatial risk multiplier; two statutory credits are required for each one biodiversity unit shortfall |
| Role in the hierarchy | Registered off-site gain can form part of the normal BNG delivery route | Final option where the applicable on-site and off-site routes cannot deliver the requirement |
Government guidance is explicit that statutory credit prices are not guideline prices for off-site biodiversity units.
For a fuller educational comparison, see BNG Units and Credits Explained.
If you are specifically researching transaction and purchase routes, see BNG Credits and Units for Sale.
What Do Off-Site Biodiversity Units Cost?
There is no single government price for private off-site biodiversity units.
Buyers and sellers agree private-market prices. These can vary with:
- habitat type and unit specification;
- location and local supply;
- timing and availability;
- the provider’s delivery and management obligations;
- legal and registration costs;
- the structure of the commercial agreement.
However, the cheapest advertised unit is not necessarily the lowest-cost solution for the project.
A candidate option can become less useful if the metric applies spatial penalties, if the unit type does not satisfy the project requirement, or if allocation cannot be completed within the programme.
In contrast, statutory biodiversity credit prices do not provide a benchmark for private units. Government guidance deliberately prices statutory credits so they do not undercut the off-site market.
For wider cost and pricing guidance, see BNG Costs & Pricing Explained.
Frequently Asked Questions About Off-Site Biodiversity Units
What are off-site biodiversity units?
Off-site biodiversity units represent habitat creation or enhancement delivered outside the development’s red-line boundary.
For statutory BNG, the relevant gains must be supported by the statutory biodiversity metric and the off-site delivery framework. Where third-party units are used, the gain site must be registered and the relevant gains allocated to the development before the Biodiversity Gain Plan can be approved.
When might a development need off-site biodiversity units?
It depends on the development’s BNG applicability, planning date, hierarchy and metric position.
For major development, current planning guidance retains an on-site-first order before registered off-site gains. For relevant non-major applications made on or after 6 August 2026, on-site enhancement, on-site creation and registered off-site gain are treated at the same level of preference.
A project-specific metric should confirm the actual off-site requirement.
Are off-site biodiversity units the same as statutory biodiversity credits?
No.
Off-site biodiversity units come from registered off-site biodiversity gains and are allocated to individual developments.
Statutory biodiversity credits are a separate government last-resort mechanism. Natural England sells them on behalf of Defra. The statutory metric also applies a specific spatial risk multiplier to credits.
Do I have to buy off-site units before applying for planning permission?
No.
Government guidance states that a developer does not have to buy off-site units before applying for planning permission.
The timing of purchase, gain-site registration and allocation can overlap. However, the applicant must record the allocation before the local planning authority can approve the Biodiversity Gain Plan.
Does an off-site gain site have to be in the same local planning authority area?
No. Providers can deliver off-site gains elsewhere in England.
However, the statutory biodiversity metric incentivises gains closer to the development. More distant gains can receive spatial penalties. The exact treatment also depends on the unit type and project geography.
What should I check before agreeing to buy off-site units?
First, check more than the headline unit number.
The review should cover the development’s required unit type and quantity, trading rules, spatial treatment, gain-site evidence, legal securing, management documents, registration and the availability of the exact gains for allocation.
The commercial agreement should also make the allocation obligation clear.
How are off-site biodiversity gains secured for 30 years?
For statutory BNG, an appropriate legal agreement must secure the off-site gains.
Current government guidance identifies a Section 106 planning obligation or a conservation covenant as the two BNG legal agreement routes. The agreement must require habitat maintenance for at least 30 years from completion of the enhancement works.
Can ACP review a gain site or provider I have already found?
Yes. If you already have a candidate provider or gain site, send the available metric information, gain-site reference, habitat information and supporting documents.
ACP can review the ecological and BNG evidence within the agreed scope. We can then identify questions to resolve before you rely on the units.
What if I do not yet know how many off-site units I need?
First, establish the shortfall.
A BNG assessment and Statutory Biodiversity Metric can determine the baseline, proposed position and remaining requirement.
Therefore, avoid buying units simply on the basis of an early estimate.
How much do off-site biodiversity units cost?
Buyers and sellers agree private off-site unit prices. These vary by habitat requirement, location, supply, timing and the provider’s delivery obligations.
In contrast, statutory biodiversity credit prices are separate government prices. GOV.UK states that they are not guideline prices for private off-site units.
For wider pricing guidance, see BNG Costs & Pricing Explained.
Discuss Your Off-Site BNG Requirement
Tell us the site location, current metric shortfall, planning stage and any gain-site option you are considering.
You do not need every document before contacting us. Please summarise what you have; we can discuss how to share supporting information securely if a review is appropriate.
Your project, site location and contact details can be provided through the enquiry form.
Prefer to talk? 0330 236 7329 · hello@acp-consultants.com.
Sources and scope
The following official guidance was checked for this research on 12 October 2026. Guidance, government fees, legal requirements and statutory-metric tools may change.
Understanding BNG · Enter a BNG legal agreement · Register a biodiversity gain site · Record allocation of off-site biodiversity gains.
Scope of this guide. This is a developer-side off-site procurement and evidence guide, not an offer of available units. Habitat trading, metric factors, provider evidence, legal securing and allocation must be checked for the particular development. Legal agreements and unit purchases need appropriate professional and commercial review.
This information supports initial ecological and planning discussions in England. It does not determine a planning outcome or replace project-specific ecological, planning, legal or commercial advice.
Disclaimer date: October 2026.