Off-site biodiversity units and statutory credits

Off-site biodiversity units are the middle tier of the biodiversity gain hierarchy, and statutory biodiversity credits are the bottom one. You have to show the council you cannot deliver the ten per cent gain on site before you buy either, and the further the off-site land is from the development, the less each unit is worth in the metric. Statutory credits are priced by government deliberately above the market so that habitat delivery, rather than a payment to the Treasury, is the rational choice.

That pricing is the whole design of the system. Treat credits as a backstop for the last fraction of a shortfall, not as a line in the appraisal.

The hierarchy and how councils police it

The biodiversity gain condition deemed attached to most permissions requires a gain plan that sets out the pre-development value, the post-development value on site, any registered off-site gains allocated to the development, and any statutory credits bought.

Officers read those in order. If the plan claims a nil on-site gain on a site with a hectare of amenity grassland, expect the question. The expectation is that you maximise what the layout can carry, then make up the balance off site.

Habitat enhancement on site means more than creating new habitat. Improving the condition of what is already there generates units too. Extending an existing hedgerow, taking mown amenity grassland to a species-rich sward with a sensible cutting regime, or moving a scrubby margin from poor to moderate condition all count, and they avoid the transaction costs that come with the tiers below. Officers know this, and a gain plan that skips straight to purchased units invites scrutiny of the layout.

Spatial risk and why distance costs you

The statutory metric applies a spatial risk multiplier to off-site units based on where the compensation land sits relative to the development.

Units delivered within the same local planning authority area, or within the same national character area, count in full. Units in a neighbouring authority or character area are discounted. Units further away are discounted more heavily. Check the multiplier values in the current version of the statutory metric before you price anything, because the metric is revised and the tool itself is the authoritative source.

The practical effect is blunt. A unit bought 200 miles away can be worth half what the same habitat parcel would be worth on the edge of the site, so the lowest headline price per unit is often the most expensive way to close the gap. Work in delivered units rather than listed units, and ask the seller to state the multiplier they have assumed for your site.

Two other multipliers bite at the same time. Difficulty of creation penalises habitats that are hard to establish, and temporal risk penalises habitats that take many years to reach target condition. A newly planted woodland scores poorly on both.

Buying units from a habitat bank

A habitat bank is land registered as a biodiversity gain site, with a management plan running at least 30 years, from which units are allocated to individual developments.

Before you commit, ask for four things. The registration entry on the biodiversity gain sites register, with the habitat types and unit numbers. The completed metric for the gain site, so you can see the baseline and the target condition assumed. The legal mechanism securing the land, whether a conservation covenant with a responsible body or a section 106 agreement. And confirmation that the units you want are unallocated.

Allocation is the step people miss. Units must be allocated to your specific development and recorded as such, and an invoice or a reservation letter is not an allocation. The Biodiversity Net Gain Assessment you submit has to name the gain site and show the allocated units, and the metric must be completed by a competent person under the Environment Act 2021 regime.

There is also a habitat type question. The metric applies trading rules, so losing a distinctive habitat cannot be compensated with a lower distinctiveness one. Medium and high distinctiveness losses have to be matched like for like or better, which narrows the market considerably for chalk grassland, lowland heath or a hedgerow with a wide species mix. On a scheme losing any of those, start the search for matching units before the application is submitted rather than after the resolution to grant.

What statutory credits are for

Statutory biodiversity credits are sold by government as a last resort where on-site and off-site delivery are not available. Buying them discharges the gain requirement for the number of units bought.

Prices are published in tiers reflecting habitat distinctiveness, and they are set high on purpose. They are reviewed, so quote the current published schedule rather than a figure from a previous scheme. Money raised is directed to habitat creation nationally, which means you get no site-specific ecological outcome and no local political credit for it. Members reading a committee report rarely warm to a scheme that pays a national levy instead of planting anything near the site.

Credits cannot be used for irreplaceable habitat. Ancient woodland, ancient and veteran trees, lowland fen, blanket bog and the other habitats on the irreplaceable list sit outside the metric altogether, and their loss has to be addressed through the bespoke compensation the planning system requires rather than through units.

Registering off-site gains

Where you control the land yourself, you can register it as a gain site rather than buying from a third party. That route suits developers with a strategic land holding or a farm within the same authority area.

The registration process requires the land to be secured for at least 30 years, a habitat management and monitoring plan, the completed metric, and the responsible party identified. Natural England operates the register, and the entry has to be in place before the biodiversity gain plan can be approved.

Allow real time for this. The legal work behind a conservation covenant or a section 106 on third-party land, the baseline survey in the right season, and the registration itself do not compress into the weeks between a resolution to grant and a start on site.

A preliminary ecological appraisal early in the process is what tells you whether the on-site tier can carry most of the requirement, and a preliminary ecological appraisal in the wrong season is the most common reason a scheme ends up in the credit market by default.

Programme consequences of relying on units

The gain plan has to be approved before development may lawfully start. So the sequence is: permission granted, gain plan submitted with the allocated units evidenced, plan approved, works begin.

Three things commonly delay that. The gain site's own baseline survey falls outside the survey season. The legal agreement securing the off-site land takes months because a third-party landowner's lender has to consent. Or the allocation is refused because the units were already committed to another scheme.

Build the off-site strategy at the same time as the layout rather than after the decision. Browse the report types PlanScope covers to see how the ecology documents fit with the rest of the submission, and enter your postcode to check which of them a site is likely to need.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. The statutory biodiversity metric must be completed by a competent person under the Environment Act 2021 regime, and an AI-assisted draft is a starting point for that person rather than a substitute. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.