What Is the Process for Purchasing BNG Units to Meet Planning Requirements?

Tim Hobern March 13, 2026

Since February 2024, most developments in England have been subject to mandatory Biodiversity Net Gain (BNG) under the Environment Act 2021. For developers navigating planning permission, one of the most common questions is: What is the process for purchasing BNG units to meet planning requirements? Where a scheme cannot fully deliver biodiversity net gain on site, developers must secure legally compliant off-site biodiversity units before their Biodiversity Gain Plan can be approved by the local planning authority (LPA). This article explains the regulatory framework, the practical steps involved in purchasing BNG units, and how to ensure compliance with BNG regulations. Understanding Biodiversity Net Gain Requirements Under the current biodiversity net gain requirements, developers must demonstrate a minimum 10% uplift in biodiversity value. The process begins with a baseline assessment of the development site using the statutory biodiversity metric. This establishes: The pre-development biodiversity value The predicted post-development biodiversity value The resulting gain or loss in biodiversity units The metric calculation quantifies habitat type, ecological quality, condition and strategic significance. It ensures that biodiversity improvements are measurable and transparent. BNG prioritises enhancing biodiversity through a structured framework known as the mitigation hierarchy: Avoid harm Minimise impacts Restore on site Compensate via off-site gains (only when necessary) Only after exhausting opportunities for on-site enhancements should developers consider purchasing offsite BNG units. Step 1: Maximise On-Site Gains The first obligation is to deliver as much uplift as possible within the red line boundary of the development site. Common BNG measures include: Retaining and enhancing existing on-site habitat Creating new habitats such as woodland, wetland or species-rich grassland Upgrading habitats such as modified grassland Integrating sustainable drainage features For major developments and many smaller schemes, achieving significant on-site gains reduces exposure to off-site costs and aligns with sustainable development principles. If, after applying the metric tool, there remains a shortfall in net gain units, off-site BNG must be secured. Step 2: Identify the Required Off-Site Units The metric output will specify: Number of biodiversity units required Habitat type (e.g. grassland, woodland, wetland) Whether any units are subject to trading rules Strategic significance requirements Importantly, BNG regulations incorporate a biodiversity gain hierarchy and a spatial element known as the BNG proximity principle. The BNG Proximity Principle and Spatial Multiplier Under the BNG spatial multiplier, units located further from the development site attract a higher unit requirement. In simple terms: Units within the same local planning authority area are most favourable Units in an adjacent LPA may be acceptable Units further afield require more biodiversity units to compensate This reflects the policy objective of maintaining ecological integrity within local habitats and protecting the natural environment at a landscape scale. The proximity principle means developers should prioritise: Onsite BNG Off-site units within the same LPA/NCA Units in an adjacent LPA/NCA Government statutory biodiversity credits (as a last resort) Step 3: Source Suitable Units from Registered Habitat Banks Offsite BNG units must come from land that is: Legally secured via a Conservation Covenant or Section 106 agreement Registered on the Biodiversity Gain Site Register Supported by a long-term monitoring plan Overseen by a designated responsible body or local authority Compliant with Natural England requirements These sites are often referred to as habitat banks or local habitat banks. Before purchasing BNG units, developers should verify: The site is formally listed on the Biodiversity Gain Site Register The units are available and unallocated The habitat type matches the trading rules The units meet proximity and spatial multiplier requirements The off-site habitat is secured for at least 30 years Failure to confirm registration risks delays in local planning approval. Step 4: Enter into a Legal Allocation Agreement When developers buy BNG units, they are securing: A quantified number of biodiversity units From a specific biodiversity gain site Legally secured for long-term habitat creation and management The agreement will typically: Allocate a defined number of net gain units Reference the gain site register entry Confirm compliance with statutory biodiversity rules Provide documentation for submission with the Biodiversity Gain Plan At this stage, units are formally linked to the development project. Step 5: Submit the Biodiversity Gain Plan Before development can commence, the developer must submit a compliant Biodiversity Gain Plan to the local planning authority. The plan must demonstrate: Pre-development biodiversity baseline Post-development biodiversity calculation On-site gains achieved Off-site gains secured Evidence of legal security Monitoring and reporting arrangements The LPA will assess whether the plan satisfies statutory biodiversity net requirements before discharging the condition. What If Off-Site Units Are Not Available? If suitable off-site biodiversity units cannot be sourced locally, developers may purchase statutory biodiversity credits from the government via Natural England. However: Statutory credits are intentionally priced higher than market units They are designed as a last resort The biodiversity gain hierarchy must be demonstrated first For nationally significant infrastructure projects, separate but aligned statutory biodiversity requirements apply, though the core principles remain consistent. Key Compliance Risks to Avoid When purchasing BNG units, developers should ensure: The biodiversity metric calculation is accurate and signed off Units are sourced from a legally secured gain site Spatial multiplier implications are accounted for The biodiversity gain hierarchy is clearly evidenced The monitoring plan aligns with statutory expectations Allocation agreements are robust and auditable Local authorities are scrutinising biodiversity gain plans carefully, and incomplete documentation may delay planning permission. At Civity At Civity, we support developers through the structured process of purchasing BNG units to meet planning requirements. We: Review statutory biodiversity metric outputs Confirm unit shortfalls and trading rule implications Identify suitable units within the relevant local planning authority area as first priority Allocate offsite BNG units from registered habitat banks Provide all necessary documentation to support Biodiversity Gain Plan submission Liaise with your project ecologist where required We do not carry out on-site ecological surveys or calculate the biodiversity metric for development land. Our role is to facilitate compliant, transparent allocation of legally secured off site units from third-party land managers. Delivering Biodiversity Net Gain with Certainty Purchasing BNG units is not simply a financial transaction. It is a regulatory step embedded within the planning system to ensure measurable biodiversity improvements. To summarise, the process involves: Completing a statutory biodiversity baseline assessment Maximising onsite BNG Identifying any shortfall in biodiversity units Applying the BNG proximity principle Securing suitable units from the Biodiversity Gain Site Register Submitting a compliant Biodiversity Gain Plan When structured correctly, off site BNG supports sustainable development while maintaining ecological integrity across local habitats. As biodiversity net gain becomes a permanent feature of planning and development plans, early engagement and careful coordination are essential to avoid delays and ensure full compliance with BNG regulations. Disclaimer This article is intended for general guidance only and does not constitute legal, ecological, financial, or planning advice. Biodiversity Net Gain requirements are governed by the Environment Act 2021, associated regulations, and guidance issued by DEFRA and Natural England, which may be updated over time. Developers should seek independent professional advice specific to their development site, biodiversity metric calculations, and local planning authority requirements before purchasing BNG units or statutory biodiversity credits.

How to Register Land for Biodiversity Credits or Nature Credits

Tim Hobern March 13, 2026

As Biodiversity Net Gain (BNG) becomes embedded within the planning system in England, many landowners are asking the same practical question: how to register land for biodiversity credits or nature credits in a compliant and commercially viable way. Under the Environment Act 2021, most developments in England are now subject to mandatory biodiversity net gain. Developers must demonstrate at least a 10% uplift in biodiversity value, calculated using the statutory biodiversity metric. Where sufficient gains cannot be delivered on site, they must secure off-site biodiversity units from a registered biodiversity gain site. This article explains how landowners can create and register a gain site, the legal steps involved, and how biodiversity units are brought to the open market. Understanding Biodiversity Net Gain (BNG) Before exploring the registration process, it is important to understand how biodiversity net gain BNG operates within the planning framework. When submitting planning applications, developers must (under Schedule 7A of the Town and Country Planning Act): Calculate the baseline biodiversity value of the development site using the DEFRA biodiversity metric tool Apply the BNG mitigation hierarchy (avoid, mitigate, compensate) Deliver as much on site BNG as possible Secure off site gains if required Demonstrate compliance within a Biodiversity Gain Plan The metric produces a quantified output measured in biodiversity units. If there is a shortfall after on-site habitat enhancement, the developer must purchase biodiversity units elsewhere to meet the biodiversity gain objective. This is where landowners play a role. What Is a Biodiversity Gain Site? A biodiversity gain site (sometimes referred to as a habitat bank or offset site) is land legally committed to delivering measurable habitat enhancement or habitat creation for at least 30 years. To qualify, the site must: Be subject to a legally binding agreement (a Section 106 agreement or Conservation Covenant) Deliver measurable uplift to biodiversity via an agreed habitat management plan, measured using the biodiversity metric Be registered on the Biodiversity Gain Site Register (maintained by Natural England) Include a long-term monitoring plan Secure oversight via the Section 106 agreement or Conservation Covenant Once registered, the land can generate offsite biodiversity units that developers may purchase to satisfy planning consent conditions. Step-by-Step: How to Register Land for Biodiversity Credits or Nature Credits 1. Confirm Land Eligibility The first stage is assessing whether your land is suitable. Key considerations include: Clear land ownership and defined land boundary No overriding constraints such as incompatible existing management covenants No legal conflicts affecting future management Ability to demonstrate genuine habitat enhancement works Underperforming arable, species-poor grassland, or marginal agricultural land often presents strong potential. However, land already delivering high biodiversity value can also have strong uplift potential under the metric by building further on a strong starting point. 2. Baseline Survey and Metric Calculation A professional ecologist must: Categorise existing habitats using the UK Habitat Classification system Assess the condition of existing habitats Apply the Statutory biodiversity metric Produce a formal metric calculation For small developments, the small sites metric may apply. However, gain sites typically require the full statutory metric tool. This establishes the baseline biodiversity value and models projected uplift from proposed new habitats or enhancement works. 3. Prepare a Habitat Management and Monitoring Plan (HMMP) A compliant document must then be prepared outlining: The habitat creation proposals Detailed habitat management prescriptions Monitoring arrangements for 30+ years Responsible parties Trigger points and reporting structure The HMMP forms part of the legal framework securing the biodiversity gain. For Civity sites, the HMMP is appended to the Conservation Covenant or Section 106 agreement and becomes enforceable on a parcel of land via a local land charge. 4. Secure the Legal Agreement Every biodiversity gain site must be secured via a legal agreement for a minimum of 30 years. There are two routes: Section 106 Agreement A planning obligation with the local planning authority, typically used where the LPA acts as enforcement body. Conservation Covenant A private agreement between the landowner and a designated responsible body, introduced under the Environment Act 2021. Both create a legally binding agreement that runs with the land and ensures delivery of habitat enhancement. 5. Register the Site Once the legal agreement is executed, the site must be entered onto the Biodiversity Gain Site Register operated by Natural England. Registration confirms: The gain site reference number Habitat types and units available Legal mechanism used Responsible body or planning authority oversight Only once listed on the register can biodiversity units be formally allocated to a development project. 6. Allocate and Sell Biodiversity Units When a developer cannot meet BNG requirements on site, they must secure off site BNG before planning permission is finalised. The developer: Identifies required unit type and number Purchases units Includes allocation details within their Biodiversity Gain Plan Submits this to the local planning authority The units are then legally linked to that development. If off-site units are not available, developers may need to purchase statutory biodiversity credits from government as a last resort, typically at a higher cost. Key Planning and Regulatory Considerations Landowners should be aware of: Interaction with existing stewardship schemes (additionality rules apply) Potential stacking with nutrient neutrality or carbon credits Flood risk and environmental constraints Local authorities’ expectations on monitoring and enforcement Ongoing compliance reporting requirements Further guidance is regularly issued by DEFRA and Natural England, particularly regarding stacking and responsible body oversight. Common Questions from Landowners Can I create a gain site on part of my holding? Yes. The red line boundary defining the biodiversity gain site can cover part of a wider landholding, provided the boundary is clearly mapped and legally secured. How long is the commitment? Habitats must be maintained for at least 30 years following completion of habitat creation. Most agreements run for 31 years minimum to accommodate establishment works in the first year. Who enforces compliance? Either the planning authority (via Section 106) or a responsible body (via Conservation Covenant) monitors compliance. The Commercial Model: Open Market vs Structured Brokerage Landowners can attempt to sell biodiversity units directly on the open market. However, this requires: Securing developers Managing legal negotiations Ensuring metric compliance Tracking allocations Administering reporting for each linked development In practice, most gain sites will serve multiple development projects, meaning several allocations over time. At Civity At Civity, we work directly with landowners to structure compliant biodiversity gain sites and bring offsite biodiversity units to market. Our staged process includes: Free desk-based assessment Scoping visit and habitat modelling Full HMMP production Legal documentation (Lease Agreement, Habitat Management Contract, Section 106 or Conservation Covenant) Registration on the Biodiversity Gain Site Register Brokerage of biodiversity units to developers Long-term monitoring and reporting for the 31-year term We do not carry out on-site ecological assessments for development land, and we do not support developers in registering habitat banks linked to their own developments. Our role is to facilitate compliant, transparent transactions between third-party landowners and developers who need biodiversity units to meet BNG requirements. Achieving Biodiversity Gain in Practice Registering land for biodiversity credits is not simply an administrative exercise. It is a structured legal and ecological commitment that must: Deliver measurable biodiversity uplift Be secured through a legally binding agreement Be transparently registered Be monitored over three decades Align with the government’s biodiversity gain objective When properly structured, it provides: Long-term income for landowners Certainty for developers seeking planning consent Measurable habitat creation A practical route to achieving net gain across England’s planning system For landowners considering how to register land for biodiversity credits or nature credits, the process requires careful technical input, robust legal documentation, and a clear understanding of planning obligations. Done correctly, it provides a compliant framework for delivering environmental enhancement alongside sustainable development — ensuring biodiversity gain is not simply a planning requirement but a meaningful contribution to long-term nature recovery. Disclaimer This article is provided for general informational purposes only and does not constitute legal, ecological, financial, or planning advice. Biodiversity Net Gain requirements are governed by the Environment Act 2021, associated regulations, and guidance issued by DEFRA and Natural England, which may be updated from time to time. Landowners and developers should seek independent professional advice tailored to their specific site, land ownership, and planning circumstances before entering into any legally binding agreement, including a Section 106 agreement or Conservation Covenant.

BNG units explained: what they measure and how they work

Tim Hobern March 10, 2026

Under the Environment Act 2021, the UK government has introduced Biodiversity Net Gain (BNG) as a legal requirement for most development projects in England. This policy ensures that all developments leave the natural environment in a measurably better state than before development, requiring at least a 10% net gain in biodiversity units. But what exactly are BNG units, how are they calculated, and what role do they play in the planning system? This article provides a clear explanation of BNG units, the statutory biodiversity metric, and how landowners and developers can navigate the new rules with confidence and clarity. What Are Biodiversity Units? Biodiversity units are a standardised measure of the biodiversity value of land, as calculated using the Statutory Biodiversity Metric. They are used to quantify both biodiversity losses from development and biodiversity gains from habitat creation or enhancement. Each biodiversity unit reflects the overall ecological quality of a habitat, calculated based on four core factors: Habitat type and distinctiveness – defined using the UK Habitat Classification system Habitat condition – assessed as poor, moderate, or good Habitat size – measured in hectares (for area habitats) or metres (for linear habitats such as hedgerows and watercourses) Location – including whether the habitat aligns with a Local Nature Recovery Strategy and attracts a strategic significance multiplier For proposed habitats, the value of biodiversity units is also influenced by three additional factors: difficulty, delay and distance. These act as negative adjustment multipliers, meaning proposed or compensatory habitats are typically worth less than existing habitats at the point impacts occur. Difficulty – how challenging the habitat is to create successfully Delay – how long the compensatory habitat will take to establish and reach its target condition after impacts occur Distance – how far the offset habitat is located from the development site In practical terms, these adjustments mean you cannot simply remove a habitat in one location and replace the same area elsewhere on a like-for-like basis. Numerically, the metric is designed to incentivise avoidance, retention and onsite enhancement over offsite replacement. BNG units are categorised into: Area habitat units (e.g. grassland, scrub, woodland) Hedgerow units Watercourse units These categories must be calculated and tracked separately using the statutory biodiversity metric tool. How Are Biodiversity Units Measured? To calculate how many biodiversity units are present on a development site, a competent person (typically a qualified ecologist) must complete the statutory metric or the Small Sites Metric for minor applications. The metric is used to assess the existing habitats on site and to model any proposed changes. It then calculates the overall biodiversity value before and after development, providing a figure in biodiversity units and the % change in value. A development must deliver at least 10% more units than it started with – either on-site, through off-site biodiversity units, or by purchasing statutory credits as a last resort. This forms the foundation of the biodiversity gain plan required as part of the planning process. What Does the Metric Consider? The statutory biodiversity metric tool scores habitats based on: Distinctiveness – how rare or ecologically valuable the habitat is Condition – the quality of the habitat Size – the area or length of the habitat Strategic significance – i.e., is identified in a Local Nature Recovery Strategy Together, these factors produce a numerical score representing the biodiversity value of each habitat parcel. The more ecologically valuable the habitat, the more units it holds. For example, a parcel of underperforming arable land might initially score only 2–4 units per hectare. If that land is restored to species-rich grassland or traditional orchard, it could generate 12–20 units per hectare depending on condition and location. Why Do BNG Units Matter for Developers? Under the new mandatory BNG requirements, developers must: Complete a BNG plan to discharge their BNG condition, prior to commencement Provide evidence using the statutory biodiversity metric Show how their development work will lead to at least 10% net gain Follow the mitigation hierarchy: avoid impacts first, then mitigate, then compensate If a development causes a net loss, developers must buy off-site units from a registered habitat bank or, as a final option, purchase statutory credits from the UK government. Local Planning Authorities (LPAs) will assess plans using the metric to ensure a consistent way of interpreting the value of a site before and after development. Why Do BNG Units Matter for Landowners? For landowners and land managers, BNG units represent a new revenue opportunity: you can sell biodiversity units to developers who need to offset biodiversity loss. Units are generated by improving or creating natural habitats—for example: Converting degraded pasture to species-rich grassland Planting and managing native hedgerows Restoring wetlands or watercourses Establishing wildflower meadows Once a site is registered on the Biodiversity Gain Site Register and legally secured (via a Section 106 agreement or Conservation Covenant), units can be sold on the open market to fulfil developer obligations. The amount a site can generate depends on factors like: How many units are deliverable The habitat type and target condition Strategic significance in the local area Your intended land management decisions over a 30-year period At Civity, we partner with landowners to navigate this process from initial scoping assessment through to site registration and unit sales, ensuring each project meets all biodiversity net gain requirements. Off-Site Units and the Role of Habitat Banks Where developers cannot meet the 10% gain on site, they must secure off-site biodiversity units from third-party landowners. These off-site units must: Be formally registered Be delivered under a legal agreement Be maintained for at least 30 years This is where habitat banks come in: they provide pre-approved habitat enhancement schemes that developers can use to meet their legal obligations. How Many Units Do Developers Need? The number of units required depends on the baseline ecological value of the development site and the impact of the planned works. A small site with few existing habitats may require only fractional units to achieve net gain. A large development affecting valuable habitats may require many more units, particularly if high-distinctiveness habitats are involved. The exact figure is determined through the biodiversity metric, and the strategy for achieving net gain must be included in the biodiversity gain plan submitted to the local planning authority. In Summary BNG units are central to delivering the government’s new approach to support biodiversity through the planning system. They provide a consistent way to measure biodiversity, track net gain, and support long-term habitat improvements across the country. Whether you’re a developer seeking compliance or a land manager exploring ways to improve your land while generating income, understanding how biodiversity units work is now essential. With the right guidance, these new rules offer a practical route to achieving environmental enhancement at scale. At Civity… We facilitate compliant and transparent Biodiversity Net Gain transactions between developers and landowners. We support developers by reviewing submitted biodiversity metrics, confirming unit requirements in line with trading rules, and brokering the allocation and sale of BNG units from registered gain sites within our landbank. We do not carry out on-site ecological surveys on developed land or register developer-owned land, but we work closely with your appointed ecologist to support completion of the Biodiversity Gain Plan. For landowners, we provide a full-service route to bringing land forward as a registered biodiversity gain site, from initial scoping through to habitat delivery, long-term management, and monitoring over the 31-year agreement term, with a focus on making nature recovery viable and rewarding over the long term.

Biodiversity net gain benefits explained: from green spaces to flood reduction

Tim Hobern March 10, 2026

Biodiversity Net Gain represents a significant shift in how development interacts with the natural environment. Introduced through the Environment Act, biodiversity net gain legislation requires most new development in England to deliver a minimum ten per cent increase in biodiversity value, measured using a statutory biodiversity metric. While biodiversity net gain requirements are often viewed as a planning obligation, the benefits extend far beyond regulatory compliance. When implemented effectively, BNG delivers multifunctional benefits ranging from enhanced urban green spaces to flood mitigation, improved air and water quality, and stronger local communities. This article explains some of many biodiversity net gain benefits, with a particular focus on urban environments and flood risk reduction. Biodiversity net gain and the planning framework Biodiversity net gain, often referred to as BNG, is now embedded within the planning framework and applies to most planning applications granted planning permission in England. The UK Government’s official guidance on biodiversity net gain sets out how developments must assess biodiversity loss, calculate biodiversity units and demonstrate net gain through a biodiversity gain plan. Local planning authorities are responsible for ensuring BNG requirements are met, with decision-making increasingly aligned to local nature recovery strategies. This integration ensures biodiversity enhancement contributes to wider environmental objectives rather than being treated as a standalone requirement. Enhancing urban biodiversity and green spaces In urban settings, inherent space constraints often limit access to natural habitats. Biodiversity net gain helps address this by embedding green infrastructure into new development and regeneration projects. Measures such as species-rich grassland creation and planting of native scrub, green roofs, street trees increase biodiversity value while improving the quality of life for local communities. Enhancing urban biodiversity supports nature recovery and protects existing habitats that might otherwise be lost to development. These improvements deliver recreational benefits, create healthier living environments and strengthen connections between people and nature in dense urban areas. Flood reduction through nature-based solutions One of the most significant biodiversity net gain benefits is its contribution to flood risk management. Climate change has increased pressure on urban flood risk management systems, particularly where natural waterways have been constrained or replaced by hard infrastructure. BNG encourages the use of nature-based solutions such as natural flood management, sustainable drainage systems, blue infrastructure and habitat creation. These approaches slow surface water runoff, improve water infiltration and reduce flood risk at a development site and downstream. The Environment Agency has emphasised the role of biodiversity net gain in recognising and enhancing watercourse and wetland habitats, aligning BNG with its goals for protecting and improving the water environment as part of its natural environment and flood risk work (see The Environment Agency’s role in Biodiversity Net Gain). Natural England alongside partners, has developed tools such as the Environmental Benefits for Nature Tool to support the integration of wider ecosystem services outcomes—including flood management and water quality—into habitat creation and enhancement associated with biodiversity net gain. Supporting local communities and the local economy Biodiversity net gain delivers clear social and economic benefits alongside environmental gains. Well-designed green infrastructure improves air quality, supports mental and physical wellbeing and provides accessible spaces for recreation. Investment in biodiversity enhancement also supports the local economy by creating green jobs linked to land management, habitat monitoring and long-term maintenance. Research from the Grantham Research Institute at the London School of Economics highlights how England’s Biodiversity Net Gain framework could be better aligned with insurance underwriting and urban flood risk management, recognising the role that habitat enhancement and natural flood management can play in reducing long-term flood risk and supporting collaboration between developers, local authorities and the insurance sector. Reducing biodiversity loss and protecting ecosystems At its core, biodiversity net gain addresses the persistent challenges of biodiversity loss caused by development. By requiring measurable net gain, the BNG system ensures that development contributes positively to ecosystems rather than simply minimising harm. Using the statutory biodiversity metric, developers or the ecologists that they work with must assess existing habitats, calculate biodiversity impacts and demonstrate how biodiversity will be created or enhanced. This evidence-based approach supports transparent decision-making and and long-term monitoring. Why early planning and local context matter Achieving biodiversity net gain is most effective when embedded early in project design. By understanding the local context, existing habitats and planning requirements from the outset, developers can make informed decisions about retaining and enhancing onsite features while also recognising where well-planned offsite units may deliver greater strategic value — for example, at a larger scale, within Local Nature Recovery Strategy areas, and created specifically to maximise long-term biodiversity outcomes. Early integration reduces reliance on off-site compensation, improves outcomes for local nature recovery strategies and increases the likelihood of a smooth planning process. Conclusion Biodiversity net gain offers far-reaching benefits that extend well beyond compliance. From enhancing urban green spaces and improving air quality to delivering flood reduction and supporting local communities, BNG represents a powerful tool for sustainable development. For developers, landowners and planners seeking to unlock the full value of biodiversity net gain, Civity provides expert support across strategy, assessment and implementation. Their team helps clients achieve biodiversity net gain in a way that aligns with planning requirements, local priorities and long-term environmental benefits. Disclaimer This article is intended as general guidance only and reflects biodiversity net gain legislation and UK government guidance at the time of writing. Requirements and interpretation may vary depending on development type, location and local planning authority policy. Professional ecological and planning advice should always be sought before making decisions.

BNG mitigation hierarchy explained: on-site, off-site, and statutory credits

Tim Hobern March 10, 2026

Biodiversity Net Gain is a mandatory requirement for most planning applications in England, fundamentally changing how development interacts with the natural environment. Introduced under the Environment Act, the BNG system requires developments to deliver a minimum ten per cent net gain in biodiversity, measured using biodiversity units. At the heart of this system sits the mitigation hierarchy, which requires developers to prioritise avoiding harm to biodiversity before considering compensation. This article explains the BNG mitigation hierarchy in practice, covering on-site delivery, off-site biodiversity units and statutory biodiversity credits, and how each option is assessed through the planning application process. Biodiversity net gain and the mitigation hierarchy explained. Biodiversity Net Gain (BNG) requires development to leave biodiversity in a measurably better state than before, delivering at least a 10% net gain secured through the planning process. It is important to distinguish between two related but separate hierarchies: The NPPF mitigation hierarchy applies to planning decisions where there is significant harm to biodiversity. As set out in the National Planning Policy Framework (NPPF), it follows the long-established sequence of avoid, mitigate, then compensate as a last resort. The Biodiversity Gain Hierarchy, explained in the GOV.UK BNG guidance, applies specifically to the statutory BNG framework and the discharge of the Biodiversity Gain condition. It is set out in Articles 37A and 37D of the Town and Country Planning (Development Management Procedure) (England) Order 2015. Under the Biodiversity Gain Hierarchy (which does not apply to irreplaceable habitats), developers must first avoid adverse effects on medium, high and very high distinctiveness onsite habitats (and mitigate where avoidance is not possible). Any remaining losses must then be addressed in a defined order: enhancement of existing onsite habitats, creation of new onsite habitats, allocation of registered offsite gains (i.e. biodiversity units), and finally the purchase of statutory biodiversity credits. Local planning authorities must consider how this hierarchy has been applied when determining whether to approve a Biodiversity Gain Plan. In summary, the NPPF mitigation hierarchy governs how significant biodiversity harm is considered in planning decisions, whereas the Biodiversity Gain Hierarchy is a statutory mechanism designed specifically to secure and evidence the required biodiversity net gain. On-site biodiversity net gain as the preferred approach On-site delivery sits at the top of the BNG hierarchy and is always the preferred option. Developers are expected to prioritise the avoidance and minimisation of biodiversity impacts through careful project design, site selection and layout decisions. Where impacts are unavoidable, habitat enhancement or habitat creation should ideally be delivered within the red line boundary of the site. On-site biodiversity net gain delivers clear ecological benefits. It keeps biodiversity improvements within the local area. For this reason, local planning authorities typically favour on-site solutions where they are feasible and deliverable. On-site measures may include enhancement of existing habitats, creation of new habitat types such as grassland or native scrub planting, or improvements to linear habitats such as hedgerows and watercourses. These proposals must be clearly documented within a biodiversity gain plan, supported by evidence, monitoring arrangements and long-term management commitments, if this is deemed by the Local Planning Authority to be required. Off-site biodiversity units and the private market Where a development cannot deliver sufficient net gain on site, the mitigation hierarchy allows for off-site biodiversity units to be used. Off-site options involve securing biodiversity units on land outside the development boundary, through habitat banks or agreements within the private market. Off-site biodiversity units must meet strict requirements. Habitat types must be appropriate, deliver genuine biodiversity enhancement/creation and be legally secured for the required period. A spatial risk multiplier is applied where biodiversity units are delivered further from the development site, reflecting the increased ecological risk of distance. DEFRA provides detailed guidance on off-site delivery, including spatial risk, habitat distinctiveness and unit calculations, within its BNG implementation guidance. This ensures off-site biodiversity does not undermine local ecosystems or planning objectives. Statutory biodiversity credits as a last resort Statutory biodiversity credits sit at the bottom of the mitigation hierarchy and should only be used where on-site and off-site options are demonstrably unavailable or insufficient. Developers must evidence why alternative solutions cannot be delivered before seeking to purchase statutory credits. Statutory credits are sold by the government and administered by Natural England, with funds used to support strategic habitat creation at a national level. The rules around statutory credit prices, purchasing and availability are set out in Natural England’s guidance on statutory biodiversity credits. These credits do not provide bespoke compensation linked to a specific development or local authority area, for every one unit required, a developer must purchase two statutory credits. As a result, statutory credits are typically less attractive than on-site or off-site solutions, both ecologically and financially. Applying the hierarchy through the planning process Local planning authorities are responsible for ensuring the mitigation hierarchy is followed. During the planning application process, applicants must demonstrate how they have prioritised avoidance, on-site enhancement and off-site options before resorting to statutory credits. Planning authorities assess biodiversity gain plans alongside planning applications to ensure compliance with national policy, local planning requirements and local nature recovery strategies. Failure to justify the chosen approach can delay determination or lead to refusal of planning permission. The Planning Practice Guidance reinforces that biodiversity net gain should be integrated early into project design and decision-making, rather than treated as an afterthought. Why early strategy and evidence are critical Effective BNG delivery depends on early engagement and robust evidence. Understanding baseline habitats, biodiversity impacts and site constraints at the outset allows developers to avoid unnecessary reliance on off-site units or statutory credits and/or be made aware early that achieving gains on-site is not a possibility. A well-considered mitigation strategy reduces planning risk, controls costs and delivers genuine environmental enhancement. Conclusion The BNG mitigation hierarchy is central to delivering biodiversity net gain in England. By prioritising on-site enhancement, using off-site biodiversity units where necessary and treating statutory biodiversity credits as a last resort, developers can meet planning requirements while contributing positively to the environment. For developers, landowners and planning professionals navigating the complexities of biodiversity net gain, Civity provides expert support across the full BNG system. From early strategies to biodiversity gain plans and implementation, their team helps ensure development proposals are compliant, evidence-led, and environmentally robust. Disclaimer This article is intended as general guidance only and reflects biodiversity net gain legislation and government guidance in England at the time of writing. Requirements may vary depending on development type, location and local planning authority interpretation. Professional ecological and planning advice should always be sought before making decisions.

hello@civitynge.com

0208 050 6076

hello@civitynge.com

0208 050 6076

CIVITY NGE Blog

What Is the Process for Purchasing BNG Units to Meet Planning Requirements?

How to Register Land for Biodiversity Credits or Nature Credits

BNG units explained: what they measure and how they work

Biodiversity net gain benefits explained: from green spaces to flood reduction

BNG mitigation hierarchy explained: on-site, off-site, and statutory credits

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