Who signs the statutory biodiversity metric
No qualification is named for completing the statutory biodiversity metric. The authority judges competence from the outputs, so the habitat survey and condition assessment have to show it.
The statutory biodiversity metric has no signature box, and that is exactly why the competent person question causes so much trouble. The Environment Act 2021 regime expects the metric to be completed by someone competent to do it, and it does not name a qualification, a register or a chartered title. The local planning authority decides whether the person who completed yours was competent, and it decides that by looking at the outputs. So the practical answer is that whoever completed the metric has to be able to demonstrate habitat identification and condition assessment skill, and the document has to show it.
What the regime requires of the author
The gain condition is deemed onto most planning permissions in England through Schedule 7A to the Town and Country Planning Act 1990, inserted by the Environment Act 2021. It requires development to deliver at least a 10 per cent increase in biodiversity value, maintained for at least 30 years, with a biodiversity gain plan approved by the authority before development begins.
The value is calculated using the statutory biodiversity metric published by Defra. The guidance accompanying it expects the habitat survey and condition assessment underlying the calculation to be carried out by a competent person, meaning someone with sufficient training and experience for the habitats involved.
There is no licensing regime here, unlike protected species work. That is a real difference. Nobody commits an offence by opening the metric spreadsheet. What happens instead is that the authority refuses to approve the gain plan, and on a scheme with a pre commencement gain condition, that stops the development.
What competence means in practice
Three capabilities matter, and they are testable from the document.
Habitat identification to the classification the metric uses, which means working confidently with the UK Habitat Classification rather than translating loosely from another system. Condition assessment against the metric's own condition criteria, which requires the surveyor to have applied each criterion in the field rather than assigning a condition category by impression. And an understanding of the metric's rules, including distinctiveness, strategic significance, spatial risk and the trading rules, because the calculation behaves in ways that surprise people who have not used it.
In practice most authorities look for membership of the Chartered Institute of Ecology and Environmental Management at an appropriate grade, evidence of training in the habitat classification and in metric use, and a professional indemnity position. None of that is a legal requirement and all of it is a reasonable proxy.
An ecologist who is excellent on bats is not automatically competent on grassland condition assessment. Ask specifically about the habitats on your site. The article on when a council can reject a report because of its author covers how authorities handle authorship questions more generally.
Habitat condition assessment and survey timing
Condition assessment is the part that most often falls apart, because it is seasonal and because it cannot be done from aerial imagery.
Botanical survey work needs the growing season, broadly April to September, with the middle of that window best for most grassland. A condition assessment carried out in January on a grassland sward is guesswork, and a competent ecologist will say so and either survey later or apply precautionary assumptions and record them.
Precautionary assumptions cut both ways and should be stated. Assuming poor condition where the survey could not confirm otherwise lowers the baseline, which makes the gain easier to demonstrate and is open to challenge from a consultee who knows the site. Assuming good condition raises the baseline and the required uplift.
Where a preliminary ecological appraisal has already been done, the habitat survey underpinning it may be reusable, and only if it was mapped to the right classification and assessed against the metric's condition criteria. A phase 1 style habitat map from five years ago usually is not.
The gain plan and the authority's approval
The biodiversity gain plan is the developer's document and the authority's decision. Its contents are prescribed, and in substance it has to set out the pre development biodiversity value, the steps taken to minimise adverse effect on that value, the post development value on site, any registered off site gains allocated to the development, and any statutory biodiversity credits purchased.
Two points on the pre development value deserve attention.
The value is assessed as at a relevant date, normally the date of the planning application, unless an earlier date is agreed. And where habitat has been degraded on or after 30 January 2020, the legislation allows the value to be assessed as it was before the degradation. That provision exists to remove the incentive to clear a site before applying, and authorities do use it.
| Stage | Who does it | What it produces |
|---|---|---|
| Baseline habitat survey and condition assessment | Competent ecologist | Mapped habitats with condition |
| Metric calculation | Competent person, usually the same ecologist | Pre and post development biodiversity units |
| Biodiversity gain plan | Developer, drawing on the ecologist's work | Document submitted for approval |
| Approval | Local planning authority | Decision discharging the gain condition |
| Delivery and monitoring | Landowner or responsible body | Management and monitoring reports over 30 years |
Sequencing matters. The gain plan is submitted after permission and before development starts, so the metric work has to be finished and consistent with the approved drawings. A layout change at reserved matters stage that alters habitat areas means the metric is redone.
Off-site units and the responsible body
Where the site cannot deliver the uplift, off site units are the next step in the hierarchy, and they have to be registered on the biodiversity gain sites register held by Natural England and allocated to your development. Buying units that are not registered and allocated achieves nothing.
The land providing them must be secured for at least 30 years, either through a conservation covenant with a responsible body designated for the purpose, or through a planning obligation. The responsible body has a continuing role, and its willingness to take on the site is part of the due diligence rather than a formality.
Statutory biodiversity credits sold by the government sit last in the hierarchy and are priced to be the least attractive option. Treat them as a contingency rather than a plan.
Errors that get a metric returned
An illustrative example of a metric that came back: a small residential scheme where the baseline was taken from a habitat map using a different classification, the grassland condition was recorded as moderate with no condition assessment sheets, the site area in the metric did not match the red line on the application drawing, and the watercourse running along the boundary was omitted entirely. Each of those on its own would have prompted a query. Together they meant the authority could not approve the gain plan.
The recurring faults are an out of date version of the metric, condition assigned without a field assessment, trading rules breached so that the units offered are not of sufficient distinctiveness, strategic significance applied without reference to the relevant local strategy, time to target condition set optimistically, and areas measured from a drawing that is not the application drawing.
A biodiversity net gain assessment drafted with AI assistance can structure the narrative, list the evidence required and flag where site data is missing, and the metric itself and the condition assessment behind it are work for a competent person. Our draft is a starting point for that professional rather than a substitute for them.
Records for the 30 year period
The obligations run long after the decision, and the records need to survive changes of ownership and of consultant.
Keep the completed metric file in its original format with the version number, the habitat survey notes and condition assessment sheets, the photographs and survey dates, the approved biodiversity gain plan, the habitat management and monitoring plan, the legal mechanism securing the land, and each monitoring report at the intervals the plan specifies.
Where a reviewer is brought in to check the work before submission, the article on peer review and sign off sets out what they will want to see, and the professional directory is the route to one.
This is general guidance rather than legal advice. Check the position with your local planning authority or a qualified ecologist 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. For specialist technical reports, qualified professional input may be required.
Frequently asked questions
Is there a qualification required to complete the biodiversity metric?
No. The regime expects a competent person, meaning someone with sufficient training and experience for the habitats involved, and it names no register or chartered title. Authorities commonly look for membership of the Chartered Institute of Ecology and Environmental Management at an appropriate grade, training in the habitat classification and in metric use, and professional indemnity cover.
Can the metric be completed from aerial imagery?
Not credibly. Condition assessment requires the surveyor to apply the metric's condition criteria in the field, and habitat identification has to be to the classification the metric uses. A condition category assigned by impression, or from imagery, is the fault authorities query most often, and it will be visible from the absence of condition assessment sheets.
What if the site was cleared before the application?
Where habitat has been degraded on or after 30 January 2020, the legislation allows the pre development biodiversity value to be assessed as it was before the degradation. The provision exists to remove the incentive to clear a site before applying, and authorities do use it where there is evidence of the earlier habitat.
When is the biodiversity gain plan submitted?
After planning permission and before development begins, because the gain condition is a pre commencement requirement. The metric work therefore has to be finished and consistent with the approved drawings. A layout change at reserved matters stage that alters habitat areas means the metric and the plan are redone.
Do off-site biodiversity units need to be registered?
Yes. Units must be recorded on the biodiversity gain sites register held by Natural England and allocated to your development, and the land has to be secured for at least 30 years by a conservation covenant with a responsible body or by planning obligation. Buying unregistered or unallocated units achieves nothing.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.