Statutory biodiversity credits and the evidence to avoid them

Statutory biodiversity credits are the final tier of the biodiversity gain hierarchy, and the government has priced them so that almost nobody wants to reach that tier. They are sold by the Secretary of State, the money is invested in habitat creation in England, and the price is set deliberately above what the off site market charges. Reaching for credits is a signal that the design, the metric work or the off site search went wrong somewhere earlier.

So the useful question is not how to buy them. It is what evidence a local planning authority will expect before it accepts that you had to.

Where credits sit in the hierarchy

The gain hierarchy runs in a fixed order, and each step has to be exhausted before the next becomes available.

First, avoid and minimise harm through the design itself: keep the good habitat, route roads around it, and do not strip what you do not need to strip. Second, deliver gains on the development site. Third, deliver gains off site, either on land you control or by buying allocated units from a registered gain site. Only then do statutory credits come into play.

Two things fall outside this entirely. Irreplaceable habitats such as ancient woodland are not dealt with by the metric at all, and no quantity of credits compensates for their loss. And development that is exempt from the gain condition never reaches the hierarchy in the first place.

The hierarchy is not a menu. An authority is entitled to ask why you are at the bottom of it and to decline to approve a gain plan that does not answer.

Evidence that the earlier tiers were exhausted

Build this evidence as you go rather than assembling it retrospectively, because a file constructed after the fact reads like one.

For the on site tier, show the metric output at more than one design stage. A record showing the baseline score, the score for an early layout, and the score for the submitted layout demonstrates that habitat was considered while the design could still move. Note the options tested and rejected, with the reason each was rejected: a road alignment that would have retained a hedgerow but failed visibility, a landscape buffer that conflicted with the drainage strategy, a wildflower area that the management company would not adopt.

For the off site tier, show the search. Record which registered gain sites were approached, in which authority areas and National Character Areas, what habitat types they held, what they quoted, and why each was unsuitable or unavailable. "No units were available" is an assertion. A dated log of eleven enquiries with responses is evidence.

Two refusals recur, and both are answerable. Where the only available units are distant and therefore heavily discounted, set out the delivered cost after the spatial multiplier and compare it against the credit price. Where the habitat type you need is not available anywhere, say which type it is and why nothing else satisfies the trading rules.

How credits are bought and recorded

Credits are purchased from the government, in tiers matched to the distinctiveness of the habitat being lost, with separate arrangements for hedgerow and watercourse units. You buy the tier that corresponds to your loss, not a general-purpose unit.

Prices are published and revised periodically, so check the current schedule rather than a figure from an earlier scheme. The purchase produces a certificate, and that certificate is what goes into the biodiversity gain plan alongside the metric calculations.

The sequence matters. The gain plan must be approved by the local planning authority before development can lawfully begin, and the plan cannot be approved without evidence that the required units are secured. Credits are quicker to obtain than a registered off site allocation, which is part of why some developers drift towards them, and that convenience is exactly what the pricing is designed to offset.

Why the price is set to be unattractive

This is deliberate policy rather than an accident of market conditions.

The regime is meant to produce habitat, and habitat delivered near the impact is worth more ecologically than a contribution to a national fund. If credits were competitively priced, the off site market would never develop, because buying a certificate is administratively simpler than negotiating a 30 year arrangement with a landowner.

Setting the price high does two things. It pushes demand into the private market, which is what creates habitat banks and gives landowners a reason to enter the market at all. And where credits are bought anyway, the premium funds habitat creation with the inefficiency of a national scheme priced in.

The practical consequence for a developer is that the credit price acts as a ceiling on what the off site market can charge, and as a strong incentive to have looked properly before accepting it.

The effect on scheme viability

Credit costs land on the appraisal as a fixed cost, and on a marginal scheme they can be the difference between proceeding and not.

Three points are worth making to a client early. The cost is driven by the number of units short and by the distinctiveness tier, so a site losing a small area of good habitat can cost more than one losing a large area of poor habitat. The cost is known in advance, which is an advantage over a bespoke off site arrangement where price is negotiated. And it is a policy requirement rather than a discretionary contribution, so it belongs in the appraisal as a cost before the affordable housing calculation rather than as something to trade against it in a viability negotiation.

Where credits make a scheme unviable, the answer is usually to revisit the layout rather than to argue about the regime.

Practical steps that avoid needing them

Most credit purchases are avoidable, and the avoidance work happens in the first two months of a project.

1. Run the metric on the earliest workable layout, not on the planning drawings. The score is an input to design, not an output of it.
2. Survey the baseline in the growing season. A February survey will record species-rich grassland as modified grassland, which undervalues retention and overstates what you can achieve by creation.
3. Protect what you keep. Habitat retained but damaged during construction has to be re-scored, and root protection areas, storage compounds and haul routes all decide whether retention survives.
4. Look for local gain sites before the application is submitted, while there is time to negotiate rather than time only to accept.
5. Reconsider the adoption and management arrangements, since a management company unwilling to maintain species-rich grassland forces the design towards amenity grass and a lower score.
6. Check the exemptions properly. A scheme affecting less than 25 square metres of on site habitat and less than five metres of linear habitat falls below the de minimis threshold entirely.

The layout work that recovers units is usually landscape work rather than ecology work, which is why the Landscape Strategy and the Biodiversity Net Gain Assessment should be produced by people talking to each other. Both depend on the habitat mapping in a Preliminary Ecological Appraisal done at the right time of year.

Enter a postcode on PlanScope to see which reports a site is likely to need, and get the ecology programme started before the layout is fixed. PlanScope drafts supporting documents structured to UK planning policy and flags where site facts are still missing. The statutory metric and the biodiversity gain plan must be completed by a competent person under the Environment Act 2021 regime, so any draft is a starting point for that professional rather than a substitute for them. Reports are AI-assisted drafts that should be reviewed before submission, and we do not guarantee planning approval. This is general guidance, not legal advice: check the current credit prices and metric version before relying on any figure.