BNG Units and Credits: How they work for Biodiversity Net Gain
Biodiversity Net Gain (BNG) is now a mandatory requirement for most developments in England, introduced under the Environment Act 2021. Under these rules, developers must measure biodiversity losses and gains in biodiversity units, and if needed, offset any shortfall using BNG units and credits. In simple terms, BNG units quantify the ecological value of habitats, while BNG credits (specifically statutory biodiversity credits) are a government-provided fallback when on-site or off-site habitat improvements can’t fully deliver the required net gain. This guide explains how BNG units and statutory credits work, the differences between them, and when Natural England’s statutory credits for biodiversity net gain come into play.
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Understanding BNG Units and Credits
BNG introduces a measurable approach to sustainable development by assigning numerical values to habitats. These values, called biodiversity net gain units, are calculated using a standardised ecological accounting metric. By contrast, biodiversity credits are purchased to make up for any unit shortfall the government provides statutory credits for biodiversity net gain as a fallback mechanism. Understanding both is crucial for regulatory compliance and effective conservation strategies on development projects. (BNG’s framework was formalised in the Environment Act 2021.)
What is a Biodiversity Net Gain Unit?
A biodiversity unit (often abbreviated as BU) represents the “currency” of biodiversity net gain. It quantifies the ecological value of a habitat, considering factors like habitat type (distinctiveness), condition, and strategic location for nature recovery. The government’s BNG metric tool calculates how many units a site has before development and how many will remain or be created after development. For example, one hectare (~2.47 acres) of low-value arable farmland might only amount to ~2 BNG units, whereas one hectare of rich, well-established woodland could be worth 20 or more units depending on its quality. (One acre of typical farmland might yield under 1 unit, whereas an acre of high-quality habitat could yield several units.) The higher the habitat’s biodiversity value, the more units it yields.
Developers must achieve at least 10% net gain in units post-development, so if a project starts with 50 units on-site, it needs to end up with at least 55 units (through habitat creation or enhancement) to meet the requirement.
What are BNG Credits (Statutory Biodiversity Credits)?
BNG credits are officially known as statutory biodiversity credits. These are essentially statutory credits for biodiversity net gain provided by the UK government as a last resort option. Unlike standard off-site units, which come from habitat creation projects in the private market, statutory credits don’t correspond to a specific local habitat project you can point to. Instead, when a developer buys statutory credits, the funds are pooled by the government to finance large-scale habitat creation or ecological restoration elsewhere in England. Statutory biodiversity credits were introduced by the Environment Act 2021 to ensure no project is left without a compensation route if local unit options fall short.
These credits are meant to prevent development projects from stalling if you cannot secure enough biodiversity units on-site or via local habitat banking (off-site providers). They come with strict conditions: before using credits, a developer must demonstrate that on-site enhancements have been maximised and that they attempted to purchase off-site biodiversity units from the market without success. In other words, credits are deliberately kept as a fallback after exhausting all other nature-based solutions in the mitigation hierarchy (avoid, minimise, remediate on-site, then offset off-site).
BNG Credits vs Units Explained
It’s important to understand BNG credits vs units and how they relate. Biodiversity units are the primary measure of net gain, obtained by either improving habitats on-site or purchasing equivalent units off-site from land managers. Statutory credits, on the other hand, are essentially a substitute for units provided by the government when you cannot obtain enough units otherwise. Here are some key differences.
Key Differences Between BNG Credits and Units
- Source: BNG units (off-site) are generated through tangible habitat creation or enhancement projects, often by conservation organisations or landowners. Statutory credits are sold by Natural England on behalf of DEFRA, with no direct link to a specific local project (the money is later used for general habitat projects).
- Usage Hierarchy: Units should be used first. Credits can only be used as a last resort after proving on-site and off-site options are unfeasible. This ensures developers follow the mitigation hierarchy and prioritise actual habitat improvements over simply paying into a fund.
- Availability: Off-site units may be available for sale in habitat banks or conservation sites within or near your project’s local area (these must be registered on the Biodiversity Gain Sites Register). Statutory credits are available nationwide from the government, but you need approval from your Local Planning Authority (LPA) to use them, and they are tied to a specific planning permission. Natural England is the only body offering statutory credits for sale to developers.
- Value per Credit: A single statutory credit is defined as only half a unit of value (due to a “spatial risk multiplier”). This means if you have a shortfall of 1 biodiversity unit, you must buy 2 credits to compensate. Off-site units do not have this penalty one unit purchased off-site equals one unit of value for your project.
Summary of Cost and Value
Statutory credits generally cost significantly more per unit than market-sourced units. The government sets credit prices with a markup to avoid undercutting the private market. For instance, as of 2025 the base price for a low distinctiveness habitat credit is around £42,000 per credit. This means effectively ~£84,000 per biodiversity unit (since two credits = one unit).
By contrast, the going rate for one biodiversity unit from an off-site provider might range roughly £20,000–£25,000 per unit. Prices can vary, but units tend to be more cost-effective and directly support local habitat enhancement.
In summary, both mechanisms ultimately contribute to the required biodiversity net gain in units. However, units reflect real on-the-ground improvements (either on-site or off-site). While credits are a payment to the government for them to arrange improvements later. Credits exist to ensure land-use change due to development can always be offset one way or another. Even if local unit options are unavailable, they are intentionally less favourable in terms of value and cost.
Calculating BNG Units (The BNG Metric Tool)
Calculating how many biodiversity units a development will lose or gain is done with a standardised statutory biodiversity metric calculator. This BNG units and credits calculator tool (currently Biodiversity Metric 4.0) is provided by Natural England. Ecologists use this metric to assess:
- the baseline biodiversity units of your site pre-development (existing habitats’ value), and
- the projected biodiversity units after development, including any new or enhanced habitats.
The metric tool considers habitat distinctiveness (e.g. a wildflower meadow scores higher than a mown lawn), habitat condition, and whether the habitat is in a strategically important location for biodiversity. It then outputs the total units lost and gained. If the post-development units are less than 1.10 times the baseline (i.e. less than a 10% net gain), you will have a unit shortfall. The metric will indicate how many additional units are needed to reach 10% and if you can’t meet those on-site, those units must come from off-site compensation or credits.
Using the Calculator for Credits
The same tool also helps determine any statutory credits needed. It will show on a “unit shortfall summary” tab how many credits (by type/tier) would be required if you go the credits route. Essentially, it doubles the shortfall units to account for the credit penalty (the spatial risk multiplier) automatically. There is also an online service to estimate the cost of statutory credits by inputting the number of credits of each type needed. This acts as a statutory credits calculator for budgeting purposes.
Because these calculations can be complex, it’s wise to engage an experienced ecologist or BNG consultant to run the metric and explore options. Our team can assist with a detailed BNG assessment and use the tool to maximize on-site gains before considering external unit purchases or credits.
BNG Units and Credits for Sale: Where and How to Buy
Once you know how many biodiversity units you need to compensate for, the next step is securing those units. Generally, there are three routes to achieve the required units (often presented as a BNG units and credits list of options):
On-site Units
Create or enhance habitat within your development site (inside the red line boundary). This might involve incorporating green infrastructure like parks, ponds, native landscaping, or wildflower areas into your project design to generate biodiversity units on-site. These on-site gains are usually the most direct way to meet some of the requirement, but space and feasibility often limit how much net gain you can deliver on-site.
Off-site Units
If on-site measures aren’t enough for the full 10% net gain, you can obtain additional units off-site. Off-site BNG units are typically for sale through habitat banks or direct agreements with landowners who have habitat creation projects. A number of marketplaces and exchanges exist for finding BNG units for sale, and the habitat must be registered on the government’s Biodiversity Gain Site Register to count towards your net gain obligation. When you buy off-site units, you are essentially paying for a portion of a habitat restoration project on another site. The landowner or provider assumes responsibility for the 30-year management of that habitat to deliver the promised units (secured via conservation covenants or legal agreements). Purchasing off-site units is a common approach for developers to meet net gain, and it channels funds into land conservation and local habitat projects.
Statutory Credits
As discussed, these are purchased from the government (Natural England) only if you cannot achieve the required units through the first two routes. To buy statutory BNG credits for sale from the government, you will need approval from your LPA confirming that on-site and off-site options have been exhausted. The process involves applying to Natural England, and credits are sold at fixed prices set for each habitat type. Once bought, you’ll receive a certificate or proof of purchase to include in your Biodiversity Gain Plan submitted with your planning application. Keep in mind credits are non-refundable and tied to a specific project permission, so they should be used only when absolutely necessary. (Natural England sells these credits on behalf of the Secretary of State for Environment; developers cannot get statutory credits from any other source.)
It’s worth noting that off-site biodiversity units can sometimes be in short supply, especially for certain habitat types or in areas with many competing developments. Early planning is crucial engage with local habitat banks or brokers early on to see what BNG units and credits for sale are available. This can save you from last-minute reliance on statutory credits. Our consultancy can help identify registered habitat sites or reputable brokers if you need to go off-site. We maintain connections with various providers in the emerging BNG market to help clients secure the units they need at a fair price.
Statutory Biodiversity Credits: The Option of Last Resort
Statutory credits deserve special attention due to their unique role in BNG. They were established in the Environment Act 2021 to ensure a safety net when you cannot secure enough units via on-site or off-site means. Because they are the last resort, the government has set strict rules on their use. If you do find yourself needing BNG statutory credits, here are key points to know:
Eligibility and Approval
You cannot simply choose credits out of convenience. To meet statutory credits eligibility requirements, you must provide evidence in your Biodiversity Gain Plan explaining why on-site and off-site solutions can’t deliver the required units. This typically means documenting that you’ve tried everything for example, showing correspondence with at least three habitat banks or land providers that couldn’t supply the needed units. Only then will the LPA and Natural England sign off on credit use, effectively confirming that statutory credits are the only remaining option. (Projects needing only a very small number of units e.g. <0.25 units may get a pass on some evidence requirements, but still must go through the proper approval.) A developer who meets these tests can then purchase BNG statutory credits as a last resort solution.
Purchase Process
After LPA confirmation, you apply to Natural England to buy the credits. The application can take several weeks to process. Each credit purchase is linked to the specific development permission; you cannot transfer them to another project. Natural England is currently the sole provider of statutory credits for sale to developers, acting on behalf of DEFRA. It’s critical to time the purchase right – do not buy credits until your planning permission is near approval and the LPA agrees, since credits are non-refundable if circumstances change.
Pricing and Tiers
Statutory credit prices are set by habitat “tier.” Less distinctive, easier-to-create habitats (like simple grassland) are Tier A1 with the lowest price (~£42k per credit), whereas high-distinctiveness or complex habitats (like certain wetlands or rare woodlands) can be Tier A3-A5 with much higher prices (some exceeding £100k per credit). Linear habitats like hedgerows have separate prices too. These prices will be reviewed periodically and potentially raised to ensure credits remain a last resort option. The steep cost is a deliberate incentive to encourage on-site and off-site unit delivery wherever possible.
Investment in Nature
On the positive side, money from statutory credit sales is earmarked for biodiversity projects. Natural England, on behalf of DEFRA, reinvests the funds into habitat creation or habitat enhancement schemes across the country, in line with requirements set under the Environment Act 2021. So although buying credits can feel like just paying a fee, it does ultimately contribute to ecological restoration and species preservation at a larger scale. In a way, it’s a form of pooling resources for nature recovery similar to how carbon credits fund climate projects, these biodiversity credits fund habitat projects. Of course, developers would prefer to see their investment benefit the local environment near their project which is why using local units is always encouraged first.
BNG Credit Pricing and What Drives It
Pricing drivers for BNG units and credits are important to understand for budgeting. Several factors influence costs:
Habitat Type & Distinctiveness
The type of habitat being created or lost greatly affects unit value and cost. More species-rich or rarer habitats (high distinctiveness) yield more units but are also more expensive to create and maintain. Statutory credit pricing reflects this, with higher tiers (for complex habitats like wetlands or ancient woodlands) costing dramatically more per credit. On the private market side, a unit of woodland or wetland from a habitat bank will likely cost more than a unit of grassland because of the work and time needed to establish it.
Location (Spatial Factors)
Units delivered locally (ideally within the same local authority or region as the impact) are preferable. If you have to go further afield for offsets, some LPAs may impose additional requirements or multipliers, and statutory credits inherently apply a spatial risk multiplier that halves their unit value. The idea is to favour local ecosystem services keeping the benefits of new habitat closer to the impacted area. This is a key reason credits only count for half a unit each, effectively doubling how many you must buy if you can’t offset locally.
Supply and Demand
As BNG is a new market, unit prices can fluctuate. In areas with plenty of landowners offering habitat banks, prices per unit might be moderated by competition. Conversely, in regions with scarce opportunities for off-site offsets, landowners may command higher prices or developers might be forced towards credits. Over time, the expansion of habitat banking is expected to increase supply and help stabilise costs, whereas statutory credit prices will always be kept high enough to stay above the market (so as not to undercut private suppliers).
Duration and Management Costs
Remember that a purchased unit isn’t a one-off creation it comes with at least a 30-year maintenance commitment. The cost of managing a habitat (e.g. replanting, controlling invasives, monitoring) over decades is built into the price. Providers of off-site units factor this into their unit sale price, and the government’s credit pricing similarly incorporates the long-term management and monitoring costs for the habitat projects it will fund. Essentially, you’re paying upfront for long-term flora and fauna protection.
For developers, understanding these pricing drivers can help in making strategic decisions: for instance, investing a bit more in on-site enhancement (even if initially costly) might save money compared to buying very high-tier credits later. Our team can perform cost-benefit analyses between improving habitats on your site versus buying units or credits, to identify the most cost-effective and sustainable approach for your project.
Benefits of Biodiversity Net Gain Compliance
While BNG requirements add an extra step in the development process, they align development with broader environmental sustainability goals. Meeting your BNG units target isn’t just about ticking a box for regulatory compliance it brings tangible benefits:
Enhanced Ecosystem Services
By creating or improving habitats, projects contribute to natural ecosystem services like flood mitigation, pollination, and air/water purification. For example, planting trees and restoring wetlands as part of BNG provides green spaces that can also help with climate change mitigation (trees sequester carbon and wetlands store floodwater). These dual benefits mean BNG contributes to climate resilience and complements efforts like carbon credits by tackling biodiversity loss alongside emissions reduction.
Nature-Based Solutions in Development
Incorporating BNG units often means integrating green infrastructure into developments such as parks, green roofs, ponds, or wildflower meadows. These features act as nature-based solutions that not only offset biodiversity impacts but also create healthier, more attractive places for people. A site with enhanced natural habitats can offer recreational space and improved wellbeing for residents or employees, aligning with principles of sustainable design and flora and fauna protection.
Positive Reputation and Stakeholder Support
Developers who proactively embrace biodiversity net gain can strengthen their reputation for environmental stewardship. Demonstrating a commitment to species preservation and habitat creation is a strong corporate social responsibility message. This can ease community concerns about land-use change and may even expedite planning approvals. In contrast, failing to plan for BNG could lead to delays or objections in the planning process.
Long-Term Conservation Legacy
BNG, especially through off-site units, channels investment into lasting land conservation and habitat restoration projects. Your development thus leaves a positive legacy by funding the restoration of nature, often in strategic locations for wildlife connectivity. Over decades, these projects contribute to local and national conservation strategies, helping to reverse biodiversity decline.
Future-Proofing and Compliance
Embracing BNG now ensures you stay ahead of evolving environmental regulations. Biodiversity net gain is part of a wider shift towards mandatory environmental considerations in planning. By developing expertise in achieving net gain, you’ll be prepared for any increase in percentage requirements or expansion of similar schemes (such as nutrient neutrality or other environmental credits markets) in the future. In short, BNG compliance is an investment in sustainable development practices that are likely to become standard across the construction industry.
Our BNG Support Services and Process
Navigating the BNG units and credits system can be complex. Our consultancy offers end-to-end support to help you achieve biodiversity net gain efficiently. Here’s how our services and process work:
Initial Ecological Assessment & Metric Calculation
Our qualified ecologists will survey your site and establish the baseline biodiversity units using the Defra/Natural England metric. We identify valuable habitats and calculate the units present before development. This is the first step in ecological accounting for your project’s impact.
BNG Strategy Development
We’ll develop a tailored plan to meet the 10% net gain requirement. This includes maximising on-site habitat retention and habitat enhancement opportunities. We propose design features (like retaining mature trees, creating wildflower areas, or adding sustainable drainage ponds) that build biodiversity into your project from the start. These nature-inclusive design measures not only help generate on-site units but can dovetail with your landscape and sustainability goals for the site.
Off-site Unit Sourcing
If on-site measures can’t fully deliver the needed units, our team will help identify off-site options. We leverage our network of habitat banks, conservation organisations, and landowners to find available BNG units for sale that match your needs (appropriate habitat type, within a reasonable distance). We’ll handle discussions, verify that any proposed offset site is properly registered, and ensure the off-site solution aligns with your timeline.
Statutory Credit Guidance
In the event that suitable off-site units are unavailable, we guide you through the process of applying for statutory biodiversity credits. We assist in preparing the necessary justification for your Biodiversity Gain Plan to satisfy the LPA that credits are needed. Our experts will also help you estimate the cost using the government’s statutory credits calculator and manage the Natural England application paperwork, so you know exactly what to expect.
Biodiversity Gain Plan & Approval
We compile the Biodiversity Gain Plan documentation for your planning application, detailing how net gain will be achieved (on-site measures, off-site agreements, and/or credit purchases). We liaise with the local planning authority on your behalf, incorporating any feedback. Our familiarity with LPA processes and regulatory compliance standards means we can anticipate and address issues, helping to get your plan approved. The goal is a smooth sign-off on BNG so your development can proceed without delays.
Monitoring and Aftercare Support
After permission is granted, we can continue to support you in implementing and maintaining the net gain measures. This can include setting up long-term habitat management and monitoring plans, or connecting you with trusted land management partners. We want to ensure the promised units (whether on-site or off-site) are delivered and sustained, securing your net gain commitment for the full 30-year period.
Throughout each step, our focus is on finding the most cost-effective and ecologically sound solution for your project. We don’t sell credits or units ourselves as independent consultants, our advice is unbiased and focused solely on what’s best for your development and the environment. By entrusting us with your BNG strategy, you save time and avoid the pitfalls of this emerging field, confident that no stone is left unturned in achieving net gain.
In the past year, we’ve delivered over 750 audit-ready reports supporting 400+ projects for developers, planners, and architects nationwide. We put quality over quantity and build lasting relationships based on trust, ensuring your planning applications are backed by robust evidence and delivered on time.
You can also drop us an email at hello@acp-consultants.com and we’ll get back to you within 24 hours to help with your inquiry!
Why Choose ACP for BNG Support?
Choosing the right partner is key to turning BNG from a hurdle into an opportunity. Here’s why clients trust us with their biodiversity net gain needs:
Expertise and Experience
We are seasoned BNG practitioners with a team of chartered ecologists and environmental planners. Having worked on numerous projects navigating the new net gain rules, we bring proven expertise to the table. Our team stays up-to-date with the latest government guidance and industry best practices, so you get accurate advice grounded in the current policy landscape.
End-to-End Service
From initial surveys and ecological accounting to liaising with LPAs and sourcing units, we handle the entire net gain process. This comprehensive approach ensures nothing is overlooked. You won’t have to juggle multiple consultants we provide a one-stop solution covering all aspects of BNG compliance.
Strategic, Cost-Conscious Solutions
We understand budget pressures and design constraints. Our approach is to creatively integrate BNG measures into your project with minimal disruption and maximum benefit. By exploring on-site options first and tapping into our network for off-site units, we help you avoid unnecessary expenses like high-priced credits. Where spending is necessary, we ensure it delivers tangible value for biodiversity and for your project’s objectives.
Local Knowledge and Networks
Our consultancy has strong relationships with local planning authorities and conservation bodies. We know what different LPAs expect in Biodiversity Gain Plans and can tailor our strategy to meet local priorities. Moreover, through our connections with habitat banks and landowners (including those on the Biodiversity Gain Sites Register), we often hear about unit opportunities early. This insider knowledge can give you an edge in securing the units you need.
Commitment to Sustainability
As an organisation passionate about the environment, we treat your BNG goals as more than just a box-ticking exercise. We genuinely care about achieving positive outcomes for nature. This means we go the extra mile to identify opportunities for ecological restoration that align with your project, and we ensure the net gain solutions we propose are robust and sustainable for the long term. By choosing us, you’re partnering with a team that shares your commitment to environmental sustainability and high standards of professional integrity.
Our track record speaks for itself. Ultimately, we aim to make the BNG units and credits process straightforward and successful for you, turning a regulatory requirement into a chance to enhance both your project and the natural world.
FAQs on BNG Units and Credits
If you’re new to biodiversity net gain, it’s common to have questions about how BNG units and credits work in practice. Below we’ve answered some of the most frequent queries developers, planners and landowners raise from costs and calculations to eligibility and the role of statutory credits.
What is a biodiversity net gain unit?
A biodiversity net gain unit is the metric used to quantify the value of a habitat in the BNG framework. One unit represents a certain amount of biodiversity value, calculated based on habitat size, type (distinctiveness), condition, and location. For instance, if you enhance a low-quality grassland to a higher-quality meadow, you gain a number of units reflecting that improvement. The exact units are determined by the Defra biodiversity metric so the value of “one unit” varies by habitat (e.g. 1 unit could correspond to a fraction of an acre of high-value habitat or several acres of low-value habitat). The key point is that units provide a standardised way to measure and compare biodiversity losses and gains across different projects.
What is a BNG credit (statutory biodiversity credit)?
A BNG credit is effectively a biodiversity unit purchased from the government as a last resort. It’s a credit you buy when you cannot create enough units on-site or purchase them off-site. Each statutory credit counts toward your net gain requirement (with the caveat that one credit equals only 0.5 units due to the spatial risk factor). Unlike buying units from a habitat bank (where you know the specific habitat project your money funds), buying a statutory credit means your money goes into a central government pot for biodiversity. In summary: a BNG credit is a “certificate” that you’ve paid to compensate for a shortfall of units, used only when other options are exhausted.
How are BNG units calculated for a development?
They’re calculated using a biodiversity metric tool provided by Natural England. First, an ecologist will assess the habitats on your site before development to determine the baseline units. Then they’ll forecast the units after development, accounting for any new habitats you create or improvements you make. The metric considers factors like habitat type, condition, area, and strategic significance. The difference between post- and pre-development units tells you if you’ve achieved net gain or if there’s a deficit. For example, if your site had 10 units before and will have only 8 units after development (due to habitat loss), you have a deficit of 2 units plus the 10% net gain (another 1 unit), meaning you’d need 3 additional units off-site or via credits.
How many BNG credits per acre can a habitat generate?
There’s no single fixed number of BNG credits (or units) per acre, because the calculation depends on habitat quality, type, and condition. Biodiversity units are calculated per habitat area using the metric typically in hectares so the number of units (and thus credits) per acre varies. For example, as mentioned earlier, an acre of ordinary arable land might be worth under 1 unit, whereas an acre of high-quality habitat (like pristine woodland or wetland) could be worth 5–8 units or even more. The range is huge because it’s easier to gain units by creating or restoring very valuable habitats. In practice, the metric tool must be used for each site to work out how many units its acres produce. The key is that improving habitat quality on that acre will increase the units it’s worth.
How many BNG units will my project need?
It depends on the size of your site, its initial biodiversity value, and the impact of your development. By law, you must end up with at least 10% more biodiversity units than you started with. A small project on mostly low-value habitat might only need a few units to achieve 10% net gain. A large project or one impacting high-value habitats could require dozens of units. The only way to know precisely is to have a biodiversity survey and metric calculation done. This will show your baseline units and how many units you need to add. Our team can perform this calculation and give you a clear target number of units to attain compliance.
When would I need to buy statutory biodiversity credits?
Only after you’ve tried and been unable to deliver the required units through on-site work or by buying off-site units. Statutory credits are intended as a last resort. You would consider buying credits if, for example, your project still falls short of the 10% net gain after maximising on-site habitat creation, and you cannot find any available off-site units (perhaps because no habitat bank has the type of units you need in the timeframe or location required). In such cases, with the LPA’s agreement, you’d purchase the necessary credits from Natural England to make up the shortfall. (Statutory biodiversity credits were established by law in 2021 and first made available once BNG became mandatory in 2023.) Essentially, if all other avenues to achieve net gain are closed, that’s when statutory credits come into play.
How much do biodiversity units and credits cost?
Prices can vary widely. Off-site biodiversity units sold by habitat banks or landowners might average around £20k to £25k per unit, though the price can be higher or lower depending on the habitat type and local demand. Statutory credits are pricier: starting at about £42k per credit (which equates to ~£84k per full unit, since two credits equal one unit). Some statutory credits for very valuable habitats cost significantly more (six figures per credit for rare habitat types). These prices are set by the government and updated periodically. The key takeaway is that using credits will usually cost more than securing equivalent units on the private market, reflecting the intention that credits are a fallback option. We can help you get current price quotes for units or credits as part of your planning.
Where can I buy BNG units or credits?
Biodiversity units can be purchased from a variety of off-site providers. These include dedicated habitat banks (organisations that create habitat banks in advance and sell units to developers), conservation groups or land trusts that have habitat creation schemes, or even local landowners who register their land for BNG offsets. There are emerging online marketplaces and registers (like the Biodiversity Gain Sites Register). Statutory biodiversity credits, however, can only be bought from Natural England via the official process they’re not available on an open market. You’d apply through the government’s system to buy the required credits once you have approval to do so. We can guide you to reputable unit providers or through the credit purchase process, depending on what you need.
Are biodiversity credits the same as carbon credits?
No they operate on similar principles but address different environmental goals. Carbon credits represent a reduction or removal of greenhouse gas emissions (for example, one carbon credit often equals one tonne of CO2 avoided or absorbed). They’re aimed at climate change mitigation. Biodiversity credits (like BNG units or statutory credits) represent an increase in biodiversity value (like creating or improving habitat) and are aimed at flora and fauna protection rather than carbon reduction. In some cases, certain projects (like planting a woodland) could generate both carbon credits and biodiversity units, but generally the markets and metrics are separate. If you’re pursuing both, you’ll need to meet the criteria of each scheme independently.
Can any developer use statutory credits, or are there eligibility criteria?
Not every developer can simply opt for credits there are strict rules. You must show that you’ve adhered to the mitigation hierarchy: avoiding harm where possible, minimising impacts, mitigating on-site, and exploring off-site compensation. Only if after doing all this you still cannot reach the 10% gain will the LPA consider allowing statutory credit use. In practice, this means credit use is more likely for projects in areas with no local offset options, or projects with very constrained sites (like urban developments) where on-site habitat is extremely limited and suitable off-site supply is lacking. Additionally, you’ll need the LPA’s confirmation and an approved biodiversity gain plan that includes the credit purchase.
Small developments with tiny shortfalls might be allowed to buy credits more readily (because finding off-site units for say a 0.1-unit deficit can be impractical), but larger projects are expected to make a robust effort to achieve net gain without credits first.
Government Guidance and Statutory References
- Guidance: Make off-site biodiversity gains as a developer. Defra.
- Securing off-site Biodiversity Net Gain: Expert legal perspectives. Natural England.
- Understanding biodiversity net gain. Guidance on what BNG is and how it affects land managers, developers and local planning authorities. Defra.
- Statutory framework & planning condition – Biodiversity Net Gain under Schedule 7A of the Town and Country Planning Act 1990; statutory regime explained in Planning Practice Guidance (GOV.UK).
- Biodiversity Gain Plan – Must be approved before commencement; Local Planning Authority decision normally within 8 weeks. See Biodiversity Net Gain Guidance (GOV.UK).
- Statutory biodiversity metric – How units are calculated, modules, factors, and guidance on early use. Statutory Metric and User Guide (GOV.UK).
- Condition Sheets & Small Sites Metric (SSM) – Official metric tools and guidance sheets. BNG Metric Tools (GOV.UK).
- Exemptions & de minimis thresholds – Householder, small self-build, and very small impacts where no priority habitat is affected. Exemptions Guidance (GOV.UK) and Defra Environment Blog.
- Off-site register & fee – Natural England guidance on registering biodiversity gain sites, with the current £639 registration fee. Register a Biodiversity Gain Site (GOV.UK).
- NSIPs timing – Government proposals indicate that BNG will apply to Nationally Significant Infrastructure Projects (NSIPs) from May 2026, pending final regulations. Defra Consultation (GOV.UK).
- Creating a Habitat Management & Monitoring Plan (HMMP) – GOV.UK guidance on how to prepare HMMPs, including monitoring and reporting requirements. HMMP Guidance (GOV.UK).
- Small Site Matric Guidance.
- Statutory biodiversity credits. Defra.
- Guidance: Understanding biodiversity net gain.
- Overview of statutory biodiversity credits
- Biodiversity net gain: where to start
- Biodiversity Net Gain (BNG) units for sale
Other Supporting References (Quick Links)
- BNG in Practice Report (2025) – Case studies showing how BNG is being delivered in real projects. Institute of Environmental Sciences.
- Biodiversity Net Gain – Principles and Guidance for UK Construction and Developments. Chartered Institute of Ecology and Environmental Management.
- BNG Research Briefing – This post note outlines the mandatory biodiversity net gain policy introduced in England in 2024 and the risks and challenges for delivering its objectives. UK Parliament.
- Biodiversity net gain: where to start. Natural England.
- Biodiversity Net Gain Report and Audit Templates- CIEEM.
- Implementing statutory biodiversity net gain. NAO.
- Mandatory Biodiversity Net Gain in England. A Guide by CIEEM.
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Next Steps
Understanding BNG units and statutory credits is essential in today’s development landscape. By planning ahead and using the right mix of on-site enhancements, off-site units, or credits, developers can not only stay compliant with the 10% net gain rule but also deliver meaningful environmental benefits. Every project that achieves biodiversity net gain contributes to a wider positive change it’s development and land-use change done in harmony with nature.
If you have a project in the pipeline, now is the time to get your biodiversity net gain strategy in place. The earlier you start, the more options you’ll have to meet the requirement cost-effectively. Our team is here to help you navigate these new waters with confidence. Contact us today to discuss how we can assist with BNG calculations, unit sourcing, or any aspect of your biodiversity net gain plan.
Explore Related Biodiversity Net Gain Resources
Understanding how biodiversity units and statutory credits work is essential to achieving compliance under the Environment Act 2021. To see how they fit within the wider process, start with the Biodiversity Net Gain Overview and our BNG Assessment Guide explaining how habitat baselines and enhancements generate unit values.
Learn to calculate habitat and hedgerow units using the Statutory Biodiversity Metric 4.0 or the Small Sites Metric (SSM), then record results within your Biodiversity Gain Plan (BGP) and Habitat Management and Monitoring Plan (HMMP).
For developers exploring offsetting or trading, our guidance on Off-Site Biodiversity Units and Registering a Gain Site explains how to secure long-term ecological value. You can also review Conservation Covenants vs Section 106 Agreements for legal delivery routes, estimate financial implications with our BNG Costs & Pricing, and download reference forms from BNG Templates & Downloads.
You can also drop us an email at hello@acp-consultants.com and we’ll get back to you within 24 hours to help with your inquiry!
- Last Updated:
- November 2025
Disclaimer: Our content is prepared by ACP Consultants’ in-house specialists and is based on current guidance, standards, and best practice in environmental consultancy. While we make every effort to keep information accurate and up to date, it is provided for general guidance only and should not be relied upon as a substitute for professional advice on specific projects. Planning authorities retain final decision-making powers, and requirements may vary between local authorities and over time. ACP Consultants accepts no liability for any loss arising from reliance on this content without obtaining tailored advice for your project.