Biodiversity gain plans: submission and approval

A biodiversity gain plan is the document that discharges the biodiversity gain condition, and no development can lawfully start until the local planning authority has approved it. The condition is deemed to be attached to most planning permissions in England by Schedule 7A to the Town and Country Planning Act 1990, inserted by the Environment Act 2021, so it applies whether or not anyone mentioned it at the application stage.

Developers who treat the plan as paperwork discover two things late. Approval is a separate determination with its own timescale, and the authority can refuse it.

What the gain plan must contain

The plan sets out how the development achieves at least a 10 per cent gain in biodiversity value over the pre-development baseline, measured with the statutory metric. Its content is prescribed, and the required elements are broadly these:

• The pre-development biodiversity value of the onsite habitat, with the date it was calculated and the metric version used
• Whether an earlier date is relied on, for example where habitat was degraded before the application
• The post-development value of the onsite habitat, including habitat created or enhanced
• Details of any registered offsite biodiversity gain allocated to the development
• The number of statutory biodiversity credits purchased, if any
• Confirmation that the completed metric calculation tool accompanies the plan

The metric file matters as much as the narrative. Officers check the habitat classifications, the condition assessments and the difficulty multipliers, and a plan submitted without a working calculation file will be returned.

Who submits it and when

The person who submits is normally the developer or their agent, before development begins. Because the gain condition is a pre-start requirement, the sequence is: permission granted, plan prepared, plan submitted, authority determines, then work starts.

Some things do not count as starting development for this purpose, and the regulations define them, so a site clearance that looks harmless can breach the condition. Check before any machine goes on site. Where the permission is a phased one, the regime works differently again, with an overall plan and phase specific plans.

Several categories sit outside the regime, including householder applications, some small scale self-build and custom build development, and development below the de minimis threshold where the habitat affected is very small. Exemptions are defined tightly. Do not assume one applies because the site is small.

The information on baseline and post development units

Baseline value is the single most contested figure. It is calculated from a habitat survey carried out to the appropriate standard, classified using the UK Habitat Classification, with condition assessed against the metric's criteria. A survey done in February will struggle to classify grassland accurately, and an authority's ecologist will say so.

Post-development values depend on the habitat proposed, its target condition, the time it takes to reach that condition and the risk that it does not. The metric applies multipliers for difficulty of creation and for temporal delay, which is why a plan that relies on creating species-rich grassland generates fewer units than the drawings suggest.

Two practical points. Keep the landscape drawings and the metric aligned, because officers compare them and discrepancies in area are common. And record the survey date, surveyor and method in the plan itself rather than in an appendix nobody opens.

Evidence of off site allocation or credits

Where onsite provision is insufficient, offsite units must be registered on the biodiversity gain sites register and allocated to your development. The plan needs the allocation evidence: the register entry, the habitat bank details and confirmation that the units are allocated to this permission rather than merely available.

Statutory credits are the last resort and are priced to be so. They are bought from the Secretary of State and used where onsite and offsite routes have been exhausted.

Offsite gains have to be secured for at least 30 years, through a planning obligation or a conservation covenant with a responsible body. That legal work takes weeks, not days, and it is the usual reason a gain plan submission slips. The obligation drafting follows the same mechanics as other agreements, discussed in our note on what changed when the pooling restriction was removed.

How the council determines it

The authority determines the plan against the statutory requirements rather than reopening the planning merits. Its ecologist, or a shared ecology service, checks the metric, the habitat classification and the security of any offsite provision, then the planning officer issues a decision.

Timescales vary between authorities and some charge a fee for the assessment. Ask at the point of permission what the local process is, who assesses it and how long they take, because that answer drives your start on site date more than anything else in the discharge programme.

The authority can refuse to approve the plan. Common reasons are a metric that does not reconcile with the approved drawings, a baseline claimed from an inappropriate survey date, offsite units that are not yet allocated, and management arrangements that are not legally secured.

Appealing or resubmitting after refusal

Most refusals are cured by correcting the document and resubmitting, and that is usually faster than any challenge. Where a dispute is substantive, the biodiversity gain regulations modify the usual planning provisions and set out how rights of challenge apply, so take advice on the current position rather than assuming a standard section 78 appeal is available.

Resubmission works best when the cover letter answers each refusal reason in order, with the corrected metric attached and the change highlighted. Officers approve what they can verify quickly.

Monitoring and reporting obligations

Approval is the beginning of a 30 year commitment. The habitat management and monitoring plan sets out what is created, how it will be managed, who does it, and when monitoring reports are submitted. Those reporting obligations are usually secured through the section 106 agreement or the conservation covenant, with the schedule of report dates written into it.

Budget for the reports, name the responsible party and make sure the obligation survives the sale of the site. A plan that relies on a management company that does not yet exist is a plan the authority will scrutinise.

Sequencing the plan against the build programme

Work backwards from the intended start on site. Allow time for the ecology survey in season, the metric calculation, the legal agreement or covenant for any offsite units, the authority's assessment, and a contingency for one round of corrections. On a site with offsite provision that sequence is comfortably a matter of months.

The single most useful habit is to prepare the metric during the application rather than after permission. The report index sets out how the biodiversity net gain assessment fits with the other supporting documents, and reform news on this regime appears on the planning law timeline.

PlanScope drafts the narrative documents that sit around the ecological work and flags where site facts are missing. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Biodiversity net gain work under the Environment Act 2021 expects the statutory metric to be completed by a competent person, so an AI draft is a starting point for that professional rather than a substitute.

This is general guidance, not legal advice, and the biodiversity gain regulations have been amended since they came into force. Check the current requirements and your local authority's process before relying on this. Enter your postcode on PlanScope to see which reports your scheme is likely to need.