Developers in England buy off-site biodiversity net gain from five sellers: landowners, habitat bank operators, brokers, trading platforms and, where it offers units, the local planning authority (GOV.UK guidance on off-site gains).
On-site work is bought from ecologists, who survey the site and run the metric, and from habitat contractors and nurseries, who build the habitat. Statutory biodiversity credits, sold by the government at fixed prices, sit at the end as a last resort.
This is a buyer's map built from official GOV.UK guidance. I am not an ecologist, and I will not pretend to be one. I do B2B outreach, so the last section covers the part I know: how a buyer and a seller find and brief each other. Ecology questions about your own site belong with your ecologist and your planning authority.
Why does the BNG rule create a supplier market?
Biodiversity net gain (BNG) is a planning condition. Schedule 7A of the 1990 planning act attaches a general condition to planning permissions in England, unless an exemption applies: biodiversity value after development must be at least 10% higher than before. Work cannot begin until the local planning authority (LPA) approves the developer's gain plan.
Defra's guidance Understanding biodiversity net gain gives three routes to the 10%: habitat on your own site, off-site units bought on the market, or government credits when nothing else closes the gap. Schemes can combine routes, and the gain plan records all of it.
Work out your mix before you call anyone: a seller can only quote against a known shortfall, in a known habitat, near a known site.
Who are the real biodiversity net gain suppliers?
Compiled from GOV.UK guidance and Schedule 7A.
| Supplier type | What they sell you | What they cannot do | Rule that governs it |
|---|---|---|---|
| Ecologist | Habitat survey before development, metric calculation, numbers for the gain plan | Change the 10% objective; the LPA reviews and checks the metric | On-site guidance, LPA guidance |
| Habitat contractor or nursery | Creation and upkeep of on-site habitat; plants and trees | Skip the long-term security that significant on-site enhancements need | On-site guidance |
| Landowner or land manager | Off-site units from their own land | Sell units that count unless the site is registered and secured by a legal agreement | Understanding BNG, counting guidance |
| Habitat bank operator | Off-site units from sites already set up for sale | Make a distant site worth as much as one near your development | Off-site guidance |
| Broker | Units arranged from other people's sites | Make an unregistered site count toward your 10% | Off-site guidance, counting guidance |
| Trading platform | Listings to compare units from several sellers | Stand in for your own check of the register | Off-site guidance |
| Local planning authority | Units, where it offers them | Skip its approval role: it still approves or refuses your gain plan, even with its own units in it | Off-site guidance |
| Government | Statutory biodiversity credits | Be used while on-site or off-site gains can still close the gap | LPA guidance |
The biodiversity gain sites register is where you check sites, but the off-site guidance says it holds no contact details and does not match buyers with sellers. You find sellers through operators, brokers and platforms, then use the register to check them.
What does the statutory biodiversity metric decide?
The metric decides how much you need to buy. Biodiversity is measured in standardised biodiversity units, calculated with the statutory biodiversity metric tool, according to Defra's BNG guidance collection. The on-site guidance puts it at the start: survey the habitat before development, then use the metric to show value before and after.
That output is your shopping list. Every seller quotes against it and the LPA checks it, so ask every supplier to quote in the same unit and habitat terms your ecologist's metric uses, or the quotes cannot be compared.
How do on-site and off-site BNG suppliers differ?
| Route | Who you buy from | Who it suits | Where the legal security sits |
|---|---|---|---|
| On-site gains | Ecologist, habitat contractor, nursery | Schemes with room inside the red line boundary (the application site edge) | Significant enhancements: 30 years through a legal agreement or planning condition, usually with an HMMP (habitat management and monitoring plan) |
| Off-site units | Landowner, habitat bank, broker, platform, LPA | Dense schemes where the shortfall cannot be closed on site | Conservation covenant or planning obligation; site on the register; at least 30 years |
| Statutory credits | Government | Only schemes where on-site and off-site gains cannot reach 10% | Recorded in the gain plan; LPA must accept the last resort case |
Timing matters off site. If the habitat is not yet secured, the off-site guidance requires a section 106 agreement (a legal planning obligation with the LPA) before permission is granted, so a habitat bank with registered, secured land takes that step off your critical path.
What should developers check before buying off-site units?
Run these checks on every off-site offer before you sign.
- Register entry. Search the site on the register. It shows the boundary map, the habitat types to be created or enhanced, and the habitats already allocated to developments.
- Habitat match. Does the habitat on the register match the type your metric shortfall calls for?
- Location. Units score higher close to your development and in areas of strategic significance, so ask for the site's distance and local strategy status.
- Legal mechanism. Ask which conservation covenant or planning obligation secures the site, and get a copy.
- Long-term management. Who manages and monitors the habitat for the full term, and what happens if the land changes hands?
- Remaining capacity. Compare what the site offers against what the register already shows as allocated to other developments.
Do not take a seller's spreadsheet on trust. Open it and check every line against the register yourself, the same way you should take a lead list apart before anyone writes the message.
An enquiry, rewritten
A vague first enquiry reads like this: "Hi, we need some BNG units for a site, can you send prices?" No seller can quote from that. Here is a rewrite for an example scheme. The numbers are illustrative.
Subject: 3.5 grassland units near Swindon, application next month
"Hello, our ecologist's metric shows a shortfall of 3.5 biodiversity units, all grassland, for a 0.8 hectare residential scheme in Swindon. We submit the planning application next month. Do you have registered grassland units in Swindon or a neighbouring authority? If so, please send the register reference, the legal agreement that secures the site, and a quote for 3.5 units. I can share the metric file today."
Short, human emails beat robotic templates, and that holds when a buyer writes to a seller too. The subject tells the seller in seconds whether they can help. The metric figure lets them quote straight away, and the register reference and legal agreement make the answer checkable.
Send it to the person who signs allocation agreements on the seller's side. Find them by their actual job title and write to them directly, not to a general inbox.
What changed for small sites?
Size now decides whether BNG applies at all. Since 6 August 2026, a planning application for a site of 0.2 hectares (2,000 square metres) or smaller no longer triggers it, according to GOV.UK guidance for local planning authorities. Measure the site area early: a scheme just over the line needs the same supplier work as a large one, at a smaller scale.
Validation is the risk. The guidance says the LPA must refuse to validate an application that arrives without the required BNG information, so a late ecologist booking can stop a scheme before anyone reads it.
How much do statutory biodiversity credits cost?
The government sets the price, by habitat tier. These are the rates on GOV.UK's statutory biodiversity credit prices page, last updated 2 June 2026:
| Credit tier | Price per credit |
|---|---|
| A1 (area habitat) | £42,000 |
| A2 (area habitat) | £48,000 |
| A3 (area habitat) | £66,000 |
| A4 (area habitat) | £125,000 |
| A5 (area habitat) | £650,000 |
| H (hedgerow) | £44,000 |
| W (watercourse) | £230,000 |
The tier follows the habitat type you are short of, and you must buy 2 credits for every 1 unit you need. One missing unit of a tier A1 habitat therefore means 2 credits and £84,000.
These credit prices apply to developments that need planning permission and, from 2 November 2026, nationally significant infrastructure projects (NSIPs), which also submit a single metric calculation with the development consent order application under the NSIP guidance. Defra reviews prices every 6 months with at least 10 weeks' notice of a change, and charges no VAT on credits.
Keep your register searches and seller enquiries on file with the gain plan: they show the LPA that credits really were the last resort.
Off-site units have no official price. The off-site guidance leaves prices and payment terms to you and the seller, so get every quote in writing and line each one up against your ecologist's metric.
What if you sell units to developers?
Read everything above from the other side and it is your sales brief. A developer arrives with a shortfall, a habitat, a location and an application deadline. The seller who answers with a register reference, the legal agreement and a quote in the same metric terms wins the comparison. No developer buys off the back of an email. They audit you first, and here the audit is a search of the register.
You are not the only seller in the room. Six months after BNG became mandatory, Natural England reported that nearly 500 sites were advertised on digital marketplaces, most of them ready or nearly ready to register. The same update said only 11 gain sites had been registered by August 2024. That is a 2024 snapshot, so check today's register before leaning on those numbers.
Finding developers starts with your own sales history. Before my team writes to anyone, we study past and current customers, then look for firms with the same profile. If you hire a cold email agency for this, ask whether they start there. For a habitat bank, that means the developments already allocated to your sites on the register, then developers building similar schemes nearby.
Then pick one market before a single email goes out: one region or one type of scheme, not every developer in England.
If you sell units, skip the full pitch in your first message, because that is the quickest way to be ignored. Offer one thing: a quote against the buyer's shortfall. Then follow up. In our campaigns, the third follow-up tends to do the best work, as long as you leave real time between each one.
Buyers: shortfall, habitat and location first, then quotes. Sellers: register reference, legal agreement and a quote in the buyer's metric terms. Whoever turns up with that first has the better chance of the deal.
Selling biodiversity units to developers and want help reaching the buyers? Book a call and I will share how I would approach it.
Questions developers also ask
Do SuDS and green infrastructure count toward the 10%?
Often, yes. Defra's guidance on what you can count lets green infrastructure and river basin management plan enhancement count in full. Sustainable drainage systems can count, some only in part, so check that page for your type. Nutrient neutrality and SANG (suitable alternative natural greenspace) count only up to no net loss (making good what the scheme removes), so the 10% must come from elsewhere. Tree felling licence restocking does not count at all.
How long does an LPA take to approve a biodiversity gain plan?
Up to 8 weeks, per the LPA guidance. A contractor booked for the week after permission can stand idle while the plan sits with the authority, so build that window into the programme and have your unit purchase evidence ready before you submit.
Does every on-site enhancement need a 30-year commitment?
No. The on-site guidance says non-significant enhancements do not normally need maintenance provisions, a management plan, a legal agreement or any fixed term. Only significant ones carry the long commitment. Your ecologist and the LPA decide which category each habitat falls into, so agree that before you price long-term maintenance.
Which metric version will the LPA accept?
Use the current statutory biodiversity metric tool. The LPA checks the metric, so an out-of-date spreadsheet from a previous scheme is a risk at validation. Ask your ecologist which version they used before any seller quotes against the figures.