Ecologist evidence checklist for off-site BNG units
Before a provider can allocate units and a planning authority can approve a biodiversity gain plan, the ecologist needs to supply the completed statutory metric, the baseline survey and habitat plan, the deficit by unit type and distinctiveness, the on-site habitat creation plan and the allocation evidence from the registered gain site.
Key facts
- The metric must be the statutory biodiversity metric or small sites metric where allowed.
- Baseline must be a UKHab survey with condition assessments, dated and by a competent person.
- Off-site units must come from a site on the biodiversity gain site register with a BGS reference.
- The gain plan is submitted after permission and before development begins.
- Planning authorities can require monitoring reports for on-site habitat for 30 years.
Last checked: 3 October 2026
What the provider needs from you
- Deficit by unit type and distinctiveness, from the metric.
- Development location and LPA, to establish the multiplier.
- Planning stage and expected decision date, to time the allocation.
- Any constraints: like for like requirements, strategic significance, timing.
What the planning authority needs in the gain plan
| Item | Detail |
|---|---|
| Completed metric | Pre- and post-development, with off-site units entered against the registered site |
| Baseline evidence | UKHab survey, habitat plan, condition assessments, photographs |
| On-site habitat plan | Creation, enhancement and 30-year management where on-site gains are claimed |
| Off-site allocation evidence | Register reference, allocation confirmation, legal agreement summary |
| Hierarchy statement | How avoidance and on-site options were considered (equal footing for minor development) |
Common gaps that delay allocation
- Hedgerow or watercourse deficits discovered late.
- Distinctiveness recorded as medium when the habitat is high, triggering like for like.
- Metric versions mismatched between applicant and provider.
- Multiplier applied incorrectly across an NCA boundary.
Refer the project through the ecologists and consultants page and we check all of this before presenting options.
A completeness check before submission
- Metric version matches the one accepted by the authority and used by the provider.
- Every habitat parcel has a condition assessment and photographs.
- Deficits by unit type reconcile between the metric summary and the gain plan narrative.
- Off-site units are entered against the registered site reference with the correct multiplier.
- The allocation confirmation, legal agreement summary and register extract are attached.
- On-site habitat has a management and monitoring plan with a funding mechanism.
Timing the evidence
The allocation must be complete before the gain plan is approved and the plan must be approved before development starts. Build the sourcing lead time into the programme: medium distinctiveness area units in days, hedgerow or watercourse units in weeks, large volumes longer.
Keeping the metric and the gain plan consistent
The most common refusal reason is a mismatch between the metric summary, the narrative and the drawings. Lock the drawings before finalising the metric, run the post-development habitat plan off the approved layout and reconcile the deficit by unit type in a single table that the allocation evidence refers to.
Key takeaways
- Metric, baseline, deficit by type, on-site plan and allocation evidence
- Register reference and legal agreement summary from the provider
- Match metric versions between applicant and provider
- Allocate before the gain plan is approved
Frequently asked questions
Can I use the small sites metric?
Only where the development qualifies and the planning authority accepts it.
Who prepares the gain plan?
Usually the ecologist on behalf of the applicant, using the provider’s allocation evidence.
Does the provider supply the register evidence?
Yes. Reputable providers include it with the allocation.
What if the metric changes after allocation?
Tell the provider. Allocations can usually be adjusted before the gain plan is approved.
Do I need a separate report for off-site units?
No. The allocation evidence sits within the gain plan, though authorities often ask for the register extract as an appendix.
Who signs the gain plan?
The applicant submits it; the ecologist usually prepares it and is named as the author.
Sources
- Biodiversity gain plan guidance, gov.uk
- Statutory biodiversity metric, gov.uk
- Biodiversity gain site register
Written by BNG Sourced by Green Acres BNG specialists and reviewed by Mike Dungait, Managing Director of Green Acres BNG, who has registered and manages two habitat banks. Indicative information, not legal or planning advice. Confirm with your ecologist and planning authority.
Related: BNG sourcing check, exemption checker, BNG unit prices, glossary, the biodiversity gain plan, ecologists and consultants.
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