
BNG Credits Explained: What Developers Need to Know About Achieving 10% Net Gain
As mandatory Biodiversity Net Gain (BNG) is in planning law across England, developers face increasing pressure to understand and comply with its core components. One of the most crucial—and often misunderstood—aspects is how to meet the required 10% net gain in biodiversity. This blog demystifies the role of BNG credits, off-site solutions, BNG units and the full spectrum of options available to achieve compliance. This is your definitive guide to “BNG Credits Explained: What Developers Need to Know About Achieving 10% Net Gain“, covering the tools, terminology, legal routes, and best practices that developers must understand to deliver biodiversity gains both on site and off site. The Goal: Achieve 10% Biodiversity Net Gain Under the Environment Act, all eligible development projects must demonstrate a minimum 10% uplift in biodiversity value compared to the pre-development biodiversity baseline. This uplift can be achieved through on-site habitat creation and off-site biodiversity gains either via purchase of BNG units or delivery of habitat off-site, or—when no other options exist—statutory biodiversity credits. This requirement applies to: Major developments (from February 2024) Small sites (from April 2024) Nationally Significant Infrastructure Projects (expected implementation from November 2025) What Are BNG Credits? BNG credits refer to statutory biodiversity credits offered by the UK government. These are a last-resort mechanism developers can purchase when they cannot secure sufficient biodiversity units through on-site or off-site measures. But BNG credits are just one part of a broader solution that also includes: Site biodiversity gains (created within the red line boundary) Off-site habitat creation/enhancement to deliver units (secured on other land) Biodiversity units purchased from a registered biodiversity gain site (listed on Natural England’s Biodiversity Gain Sites Register) Understanding Biodiversity Units and Metrics The basis for any BNG calculation is the statutory biodiversity metric, which uses habitat type, size, condition, and location to assess the biodiversity value of a site. The latest statutory biodiversity metric tool calculates how many biodiversity units a site starts with and how many it delivers after development. Using the standardised biodiversity metric, developers can: Measure existing habitat and any habitat lost Assess the impact of the proposed development on existing biodiversity Quantify planned habitat creation or enhance habitat interventions Determine any shortfall between gains and the mandatory 10% The Biodiversity Gain Hierarchy Meeting BNG obligations must follow the biodiversity gain hierarchy, a structured process that prioritises sustainable and ecologically beneficial outcomes: Avoid biodiversity loss where possible Minimise unavoidable losses Restore biodiversity on site Secure off-site biodiversity gains Buy statutory biodiversity credits (only as a last resort) Following this hierarchy is not optional. Local Planning Authorities (LPAS) expect to see evidence that developers have pursued significant on-site gains and suitable off-site units before purchasing statutory credits. On-Site vs. Off-Site Gains Achieving BNG On Site On-site solutions are often preferred, especially for developments with adequate space for suitable habitat creation or biodiversity enhancements. Benefits include: Direct control over habitat management Alignment with the site’s design and post-development landscape Stronger connection with local communities and the site’s biodiversity However, on-site gains are not always viable, especially where: Development density is high High-scoring habitats are impacted The red line boundary limits the available space Securing Off-Site Gains When biodiversity cannot be fully addressed on site, developers may: Enhance biodiversity on your own land outside the red line Purchase off-site biodiversity units from land managers, brokers, registered habitat banks, or BNG sites listed on the official register or purchase Statutory Biodiversity Credits from the government (as a last resort). To be valid, these off-site gains must: Be registered on the Biodiversity Gain Sites Register Be secured via a legal agreement (such as a conservation covenant or Section 106) Deliver gains calculated using the statutory biodiversity metric formula. You will need to discuss with a provider to check when their site will be registered and ensure this timeline aligns with when you require the units. When to Buy Statutory Biodiversity Credits Buying statutory biodiversity credits is a viable option only when: You can’t secure or manage gains on your own land On-site options have been exhausted per the biodiversity gain hierarchy There are no suitable off-site biodiversity gains available Natural England is selling statutory credits on behalf of the Department for Environment, Food and Rural Affairs (DEFRA). Funds from the sale of statutory credits will be invested in habitat creation or enhancement. That said, credits: More expensive than market-based biodiversity units Do not generate site-specific ecological value as they are not necessarily to be delivered close to the development site Considered less favourable by LPAs Legal Requirements for BNG Credits and Off-Site Units Whether you’re securing off-site units or purchasing BNG credits, the arrangements must be legally binding and fully documented. This includes: A clear biodiversity gain plan Confirmation that the site or credits are registered Alignment with the mandatory biodiversity net gain standards The Role of Local Planning Authorities Local authorities play a critical role in verifying BNG compliance. They will: Review your planning permission application for BNG completeness Evaluate your biodiversity gain site or off-site BNG source Check that your use of statutory credits follows the rules Early engagement with the relevant planning authority helps streamline the process and avoids costly delays. How to Demonstrate BNG in Practice To support your application, your BNG documentation should include: A baseline biodiversity assessment using the statutory biodiversity metric tool Details of proposed habitat creation or enhancements Identification of any habitat lost Explanation of on-site and off-site delivery options Confirmation of any BNG units purchased or credits used All figures must be grounded in measuring biodiversity using standardised tools. Choosing the Right Off-Site Provider Not all off-site providers are created equal. Choose a partner who can: Offer legally compliant, registered biodiversity gain sites . If not yet registered, ensure they can provide a timeline for when full unit sales will be available Provide clear information on how many biodiversity units are available Align their sites with the biodiversity metric and habitat types needed for your offset (i.e. your trading requirements are met) Deliver habitat creation projects with robust long-term land management Key Considerations When Buying BNG Credits Credits typically come at a premium cost compared to equivalent off-site units You need to demonstrate you’ve thoroughly explored all alternative options first Local Planning Authorities and Natural England require robust justification for pursuing the credit purchase route While credits support broad habitat creation at a landscape scale, they may not directly benefit or connect with the biodiversity specific to your development area FAQS: BNG Credits and Units How many biodiversity units do I need? This depends on your pre-development biodiversity value and the calculated loss vs. gain. The statutory biodiversity metric provides exact figures. If buying BNG units, the number of units you need to buy will depend on the location of your development in relation to the location of the habitat bank. For every 1 biodiversity unit you require, you will need to buy 2 biodiversity credits! Can I split gains between on-site and off-site? Yes. Many developers use a combined on-site/off-site approach to balance feasibility and compliance. Are statutory credits always accepted? Only if you’ve met the conditions of the biodiversity gain hierarchy can you show there are no practical alternatives. Final Thoughts Delivering 10% biodiversity net gain is not just a planning hurdle—it’s an opportunity to make development projects more resilient, responsible, and nature-positive. Understanding when and how to use BNG credits and when to pursue off-site biodiversity units is essential for both legal compliance and ecological credibility. At Civity, our role is to review the metric and provide the right types and numbers of units. Need help assessing your site or sourcing BNG units? Contact the Civity team or explore our landbank for reliable, register-ready off-site biodiversity gains.