Biodiversity gain plan: what the form asks for

The biodiversity gain plan is filed after planning permission is granted and before development begins. It goes to the local planning authority on the form the government publishes, and until the authority approves it, the deemed biodiversity gain condition stops work on site. Treat it as a programme item on the critical path rather than a piece of post-permission paperwork, because a plan that goes back and forth twice can hold a start date for weeks.

The requirement comes from Schedule 7A to the Town and Country Planning Act 1990, inserted by the Environment Act 2021. What follows works through what the form asks for, in the order the authority reads it.

Confirm first whether the requirement applies

Several categories sit outside the regime, and the first thing to establish is whether yours is one of them. The exemptions include development below the small-scale threshold, where the works affect only a very small area of on-site habitat and a short length of hedgerow, householder applications, self-build and custom build schemes within the stated limits on unit numbers and site area, and development on a biodiversity gain site itself. Urgent Crown development and certain other categories are also excluded.

Do not assume an exemption. Record the reasoning in writing and put it to the case officer before permission is issued, because arguing about it after the decision notice has been served with the condition attached is much harder than settling it beforehand.

Pre-development biodiversity value and its date

The first substantive field. The plan states the pre-development biodiversity value of the onsite habitat, expressed in biodiversity units from the statutory metric, and the date on which that value was calculated.

The default date is the date of the planning application, though an earlier date can be agreed with the authority. There is also an anti-degradation provision: where habitat was cleared or damaged on or after 30 January 2020, the authority can require the value to be assessed as it stood immediately before that activity. So the survey date, the metric version used and the evidence of what was on the ground all have to be recorded, and a metric completed for the application stage should be checked rather than simply attached, because habitat conditions may have changed.

Attach the completed metric calculation file. Authorities want the working, not the summary figure.

Steps taken to follow the mitigation hierarchy

The plan has to describe the steps taken, or to be taken, to minimise the adverse effect of the development on the biodiversity of the onsite habitat. That is the mitigation hierarchy in plain words: what was avoided, what was reduced, what is being compensated and why.

Write this as a narrative tied to the layout. Retained hedgerows and their buffers, trees kept with their root protection areas, the watercourse corridor left undeveloped, the phasing that keeps clearance outside the bird nesting season. Where something was lost, say what alternative was considered and why it was not workable.

This is the section most often written as a paragraph of generalities, and it is the one an authority ecologist reads most carefully. A Preliminary Ecological Appraisal usually contains most of the material, and it needs restating here as decisions rather than findings.

Post-development value: on-site, off-site and credits

Three separate figures, each evidenced differently.

On-site post-development value comes from the metric, based on the habitat creation and improvement proposed, with the condition to be achieved, the time to target condition and the management assumptions stated.

Off-site value comes from land registered on the biodiversity gain sites register and allocated to this development. The plan gives the register entry, the allocation, the units and the habitat types. A site that is not yet registered cannot be relied on, and registration takes time, so start it early.

Statutory biodiversity credits are the last resort, purchased from the government at the published price. Where credits are used, the plan records the purchase. Check the current price schedule rather than a figure carried over from an appraisal, because the tiers are revised.

The three together have to deliver at least a 10 per cent gain over the pre-development value.

Irreplaceable habitat, recorded separately

Where the development affects irreplaceable habitat, such as ancient woodland or an ancient or veteran tree, the plan includes information about that habitat and about the arrangements made for minimising the adverse effect and any compensation agreed with the authority. The percentage requirement does not apply to that habitat, which is not a relaxation, since national policy sets a high bar against its loss in the first place.

Keep this in its own section with its own heading. Mixing it into the metric discussion is a reliable way to generate a query.

Habitat creation and management schedules

The authority is looking for a plan it can secure and monitor for 30 years. Provide a habitat creation and improvement schedule that names each parcel, gives its area or length, the target habitat type and condition, the establishment works, the management operations by year, and the monitoring and reporting arrangements.

Then say how it is secured. On-site habitat is normally secured by planning condition or by a section 106 obligation, off-site habitat by a section 106 agreement or a conservation covenant with a responsible body, and both are registered. Name the mechanism in the plan rather than leaving it implied.

Where the scheme is phased, the regime allows for phased plans with an overall plan setting the framework and individual plans for each phase. Outline permissions work similarly, with the detail following the reserved matters. Our outline application checklist covers how to sequence that so a phase is not held up by information that belongs to a later one.

What the authority checks, and how it decides

The authority approves or refuses the plan. It has to be satisfied that the pre-development value is as stated, that the metric has been applied correctly, that the 10 per cent gain is achieved, that any off-site units are registered and allocated to this development, and that any credits have been bought.

Practical causes of refusal or delay are consistent: a metric completed by someone whose competence is unclear, a survey carried out at a time of year when the habitat could not be properly identified, off-site units named but not yet registered, management schedules with no named responsible party, and a mitigation hierarchy section that describes the ecology rather than the decisions.

There is no conventional planning appeal against a refusal to approve a plan, so the practical route is to resolve the authority's concerns and resubmit, and to take advice early if the disagreement is fundamental rather than one of detail. Keep the ecologist available through this stage rather than closing their appointment at permission.

A submission checklist

1. Confirm no exemption applies and record why.
2. Attach the completed statutory metric file, with the survey date and surveyor named.
3. State the pre-development value and the date it was assessed, addressing any clearance since 30 January 2020.
4. Write the mitigation hierarchy section as decisions tied to the layout.
5. Give on-site, off-site and credit figures separately, with register entries for off-site units.
6. Deal with irreplaceable habitat in its own section.
7. Provide the creation and management schedule with a 30 year monitoring regime and the securing mechanism.
8. Submit at least a few weeks before the intended start on site.

A Biodiversity Net Gain Assessment is one of the report types where a competent person is required by the regime, so the metric and the plan should carry that person's name. Browse the full report index to see how the ecology evidence fits with the rest of the submission.

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.