Under the UK’s Biodiversity Net Gain (BNG) legislation, most developments are now legally required to deliver a measurable uplift in biodiversity. Where this uplift, known as the net gain, cannot be fully achieved on the development site, developers must buy BNG units from third-party habitat banks or, as a last resort, purchase statutory biodiversity credits from the UK government.
This blog offers a clear and compliant guide on how to buy BNG units: a step-by-step guide for developers, planning consultants, and land managers navigating the new planning framework.
Step 1: Establish Your Biodiversity Deficit
Before seeking off-site solutions, you must complete a baseline assessment of your site. This involves:
- Identifying habitat types and their ecological quality;
- Calculating the pre-development biodiversity value;
- Forecasting post-development biodiversity value, including any retained onsite habitats and biodiversity improvements.
These values are calculated using the Statutory Biodiversity Metric, the official DEFRA tool. The outcome will confirm whether you can meet the biodiversity net gain BNG requirement on site or whether you must purchase BNG units elsewhere.
Step 2: Apply the Biodiversity Gain Hierarchy
The mitigation hierarchy and biodiversity gain hierarchy require that developers:
- Avoid biodiversity loss where possible;
- Enhance habitats on site through BNG measures;
- Deliver off-site gains using off-site biodiversity units;
- Use statutory credits only as a last resort.
Step 3: Consider Spatial and Legal Constraints
When sourcing off-site BNG, you must consider the BNG spatial multiplier and proximity principle:
- Units sourced closer to your local planning authority area (LPA) attract a lower multiplier;
- Offsite BNG units located in an adjacent LPA or within a national network are preferable to distant or unrelated options.
You must also ensure that any BNG units you purchase are:
- Delivered on a legally registered biodiversity gain site;
- Accompanied by a formal legal agreement (either a Section 106 or Conservation Covenant);
- Legally secured for a minimum of 30 years, with a detailed monitoring plan and ongoing habitat management.
Step 4: Engage a Recognised Broker or Landbank
To avoid non-compliance or delays in gaining planning permission, it is advisable to use a recognised intermediary to buy BNG. At Civity, we match developers with suitable units available from registered landowners through our national portfolio of habitat banks.
We assist with:
- Identifying off-site units that satisfy your BNG obligations;
- Confirming alignment with local habitats, priority habitats, and local communities’ priorities;
- Providing legally required documentation for your Biodiversity Gain Plan;
- Liaising with your Local Planning Authority and the Biodiversity Gain Site Register.
We do not support registration of own land by developers or provide ecological fieldwork, but we work closely with your appointed consultant to complete the off-site aspects of your BNG unit strategy.
Step 5: Request a Formal Quote and Reserve Units
Once a compatible gain site is identified, you’ll receive a formal quote outlining:
- The number and type of net gain units available;
- The habitat type and ecological integrity of each parcel;
- The legal route (Section 106 or Conservation Covenant) and associated legal agreements;
- The timeframe and cost to purchase BNG units, including brokerage- for fully registered units, this is fast and simple.
Once approved, Civity will reserve the BNG units, update the statutory register, and ensure they are committed to your specific development.
Step 6: Finalise Your Biodiversity Gain Plan
Civity will assist with completing your Biodiversity Gain Plan: the pro forma submitted to the Local Planning Authority to demonstrate how your application will meet the BNG requirements. The final Biodiversity Gain Plan must demonstrate how the development will achieve a minimum 10% gain in biodiversity, including:
- On-site enhancements;
- Offsite biodiversity enhancements using secured offsite BNG units;
- Legal and spatial documentation;
- Reference to the appropriate biodiversity metric, including spatial multipliers.
This plan will be assessed by your Local Planning Authority as part of the planning application process. It must include mapping, confirmation of legally protected unit delivery, and a timeline for habitat creation and management and monitoring.
Step 7: Deliver Net Gain with Confidence
Once your plan is approved and your BNG units are legally secured, your development can proceed. You’ll be required to ensure:
- That biodiversity gains are delivered as agreed;
- That monitoring plans are implemented over the 30-year period;
- That the LPA or Responsible Body can assess progress and verify delivery.
Civity works with both parties throughout the process to ensure that delivery remains on track and that the units you’ve secured continue to provide measurable ecosystem services and biodiversity improvements.
Purchase BNG Units Today!
We help developers purchase BNG units from a growing network of registered habitat banks across England. Our service includes verifying BNG regulations, matching your requirements to suitable off-site units, and facilitating all necessary legal agreements. We do not register developer-controlled land or conduct baseline ecological surveys.
A Compliant Route to BNG Delivery
Buying BNG units is no longer a niche option; it’s a standard part of the planning process for both major developments and small sites. By following the correct steps, engaging expert intermediaries, and working within the legal and spatial constraints of the BNG framework, you can ensure compliance while contributing to meaningful, long-term biodiversity enhancement.
Whether you’re dealing with priority habitats, biodiversity credits, or complex BNG spatial considerations, the key is to act early, use trusted sources, and align with the wider aims of sustainable development.
