The biodiversity gain site register and how entries work

The biodiversity gain site register is the public record of land where habitat has been created or enhanced for the purposes of the statutory biodiversity gain regime, and of which developments the resulting units have been allocated to. It exists so that off-site gains can be verified rather than asserted, and so that the same units cannot be sold twice. For anyone reviewing an off-site arrangement, the register is the first document to look at and the one that answers the question a habitat bank's marketing material does not: are these units real, are they secured, and are they still available?

The register is operated by Natural England under the Environment Act 2021 framework, with the detail set out in the Biodiversity Gain Site Register Regulations 2024.

What the register records

Each entry ties together five things, and a reviewer should be able to find all five.

The land itself, identified by a plan and a description, so the extent of the gain site is unambiguous. The person who applied and their interest in the land. The habitat enhancement, expressed through the statutory metric as a pre-enhancement and post-enhancement biodiversity value, which yields a number of units. The legal mechanism securing the enhancement, which must be either a planning obligation or a conservation covenant, running for at least thirty years. And the allocations, recording which development each parcel of units has been assigned to.

That last element is the one that matters commercially. Units that appear on the register are not necessarily available. An entry showing 12 habitat units with 9 already allocated leaves 3, and a reviewer who reads the headline figure without the allocations has misread the entry.

Units come in three currencies that are not interchangeable. Habitat units, hedgerow units and watercourse units are recorded separately, because the trading rules treat them separately. A development with a hedgerow deficit cannot satisfy it with area-based habitat units.

Who may apply to register land

The applicant must be the owner of the land, or have the owner's consent, and must be able to demonstrate that the habitat enhancement is secured for at least thirty years. In practice that means the legal agreement has to be completed before the registration application, not promised alongside it.

Three applicant types recur. A landowner registering a field as a habitat bank for sale to multiple developers. A developer registering land it owns to serve its own scheme, where on-site gains fall short. And a responsible body or land manager acting under a conservation covenant arrangement.

Each has its own weak point. A landowner selling units needs a funding mechanism for thirty years of management. A developer registering its own land needs the land to be outside the development's red line and to remain so. And an arrangement held under a covenant depends on the responsible body still being designated in twenty years, which is a question of governance rather than ecology.

Evidence required for an entry

The application has to carry the technical work, and this is where incomplete submissions fail. Expect to provide:

1. A completed statutory biodiversity metric calculation showing the pre-enhancement baseline and the post-enhancement target, with the habitat types, condition assessments and areas behind both.
2. A habitat management and monitoring plan covering the thirty year period, with the creation works, the target condition, the timetable and the monitoring and reporting regime.
3. The completed planning obligation or conservation covenant, with the parties and the term.
4. A plan of the land at a scale that allows the boundary to be identified on the ground.
5. Declarations about the accuracy of the information, which carry consequences, since the regulations provide for financial penalties where false or misleading information is supplied.

The metric calculation must be completed by a competent person. Under the Environment Act 2021 regime the statutory metric and the habitat condition assessment behind it expect competent professional input, and the biodiversity gain plan has to be approved by the local planning authority. An AI-assisted draft of a Biodiversity Net Gain Assessment is a starting point for that competent person rather than a substitute for their work, and the habitat condition assessment cannot be done from a desk. The same applies to the Preliminary Ecological Appraisal that usually precedes it.

How units are allocated to a development

Allocation is the act of assigning registered units to a specific development. It can be done at the point of registration or later, by an application to amend the entry, and the register then shows the development reference against the units.

The allocation has to work under the trading rules, which is a separate question from availability. Those rules require the gains to be of the same broad habitat type as the losses or better, with distinctiveness driving what can substitute for what. Spatial location matters too: units delivered further from the development site attract a multiplier that reduces their value, so 10 units on a distant site do not necessarily discharge a 10 unit deficit.

So a reviewer checking an off-site proposal has four questions, in order. Are the units on the register. Are they unallocated. Do the habitat types satisfy the trading rules for this development's losses. And after the spatial multiplier, do they deliver the required gain. Getting a yes to the first two and a no to the fourth is a common and expensive discovery.

Removing or amending an entry

Entries are not immutable. Applications can be made to amend an entry, for example to record a further allocation, to correct an error or to reflect a change in the land or the agreement. The register operator also has powers to remove land from the register in specified circumstances.

Removal is the risk worth understanding. If a gain site is removed after units have been allocated to a permitted development, the development's biodiversity gain plan has been approved on a basis that no longer holds. The practical protection is contractual: the agreement under which units are purchased should deal with what happens if the entry is amended or removed, and should include warranties about the status of the entry at completion.

Check the entry again immediately before relying on it. A register search carried out three months earlier is not evidence of the current position.

Fees and the application process

Registration carries a fee, and separate fees apply to amendments. The amounts are set by regulations and are revised, so take them from the current gov.uk guidance rather than from an earlier project file.

Allow time. A registration application with a completed legal agreement, a metric calculation and a thirty year management plan is a substantial submission, and the operator may come back with queries on habitat condition or on the drafting of the agreement. Treating registration as a two week administrative step is how a scheme's programme slips.

Interaction with the gain plan

The biodiversity gain condition is deemed to be imposed on most planning permissions, and it prevents development beginning until the authority has approved a biodiversity gain plan. That plan sets out the pre-development biodiversity value, the on-site and off-site gains relied on, and any statutory credits.

Where off-site units are relied on, the gain plan identifies the registered gain site and the allocation. So the register entry, the allocation, the legal agreement and the gain plan have to describe the same land, the same units and the same dates. A mismatch between them is the commonest reason a gain plan is not approved first time. The way the deemed biodiversity gain condition operates is worth understanding before any of this is commissioned, as is the position on irreplaceable habitats, which sit outside the metric altogether.

Checking a proposed off-site arrangement

A short checklist for a reviewer. Search the register and obtain the entry. Confirm the units by type and the balance unallocated. Read the legal agreement for the term, the parties and the management obligations. Read the habitat management and monitoring plan for whether the target condition is realistic on that soil and in that location. Check the metric version used, because versions change and a calculation run on a superseded version may not be accepted. Confirm the spatial relationship to the development and the multiplier that follows. And check who holds the funding for thirty years of management.

Then write down what you checked and when. A reviewer's file note is the document that matters if the arrangement is questioned later.

Follow the position on the planning law timeline, because this regime is still being adjusted.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.