Short answer
Before you bid, exchange or pay an architect, you need to know whether BNG is a £0 exemption, a £5k on-site tweak, or a deal-breaking off-site liability that wipes out plot count. Our desktop Biodiversity Net Gain screening tells you which of those four worlds your site sits in, in 48 hours, for £199.
Mandatory 10% Biodiversity Net Gain has applied in England since February 2024 for major development and April 2024 for small sites of 1 to 9 dwellings, under the Environment Act 2021 and the Statutory Biodiversity Metric. Our screening identifies trigger status, exemption position, an indicative habitat baseline, and the likely delivery route (on-site, off-site units, or statutory credits) so you can price the risk before you commit.
Order a Site Appraisal or See a sample report. From £199.
When BNG screening is triggered
Mandatory BNG came into force in England from February 2024 for major development, defined as 10 or more dwellings, or a residential site of 0.5 hectares or more, with equivalent thresholds for other use classes. The regime extended to small sites from April 2024, covering 1 to 9 dwellings or sites up to 0.5 hectares. The statutory basis is the Environment Act 2021, with the Statutory Biodiversity Metric as the calculation tool. The GOV.UK biodiversity net gain guidance is the primary policy reference.
Limited exemptions apply in England: householder applications, biodiversity gain sites, sites meeting the de minimis threshold (development affects less than 25 sqm of on-site priority habitat and less than 5m of linear priority habitat), self-build and custom-build under 9 dwellings, and urgent Crown development.
The position in Wales, Scotland and Northern Ireland differs and is outside the scope of this guide. Wales operates under Section 6 of the Environment (Wales) Act 2016, which carries a different duty.
For small developers buying infill plots, garden land, barn conversions or small brownfield parcels, the screening tells you whether your site is exempt, near-exempt, or non-exempt. For sites likely exempt under the de minimis rule, the screening evidences the exemption position with desktop habitat measurements. For non-exempt sites, it indicates the baseline habitat units, the 10% target and the likely delivery route.
What our desktop BNG screening covers
The desktop BNG layer draws on Defra MAGIC, Natural England priority habitat inventories, OS MasterMap and current aerial imagery, returned within 48 hours of a confirmed boundary.
You receive a written report with:
- BNG trigger status (major, small site, or out of scope) with the threshold evidence
- Exemption check against the five statutory exemptions, with supporting measurements where de minimis is in play
- Indicative habitat map of the red line, with parcels classified to UKHab broad categories
- Indicative baseline habitat units and a 10% post-development target range
- On-site delivery feasibility comment given site area, retained habitat and achievable enhancement
- Off-site units indicative cost, drawn from the Defra BNG marketplace and known habitat banks in the planning authority area
- Statutory credits fallback cost, drawn from the Defra credit price schedule
- Survey triggers: which seasonal protected species surveys are likely needed and the survey window
- Section 106 BNG monitoring obligation indicator based on local planning authority practice
- Proximity flag for Special Areas of Conservation and Special Protection Areas, where a formal Habitats Regulations Assessment by a chartered ecologist may be required
| Input layer | Sourced from |
|---|---|
| Indicative habitat baseline | Defra MAGIC priority habitat inventory and OS MasterMap habitat parcels |
| Desktop habitat condition estimate | Aerial imagery and Phase 1 habitat overlay (indicative only) |
| Distinctiveness banding | Statutory Biodiversity Metric distinctiveness categories |
| Indicative 10% target | Metric estimate based on desktop parcels |
| Off-site units availability | Defra BNG marketplace and habitat banks |
| Statutory credits cost estimate | Defra credit price schedule |
| Exemption check | Statutory Instrument criteria |
| SAC/SPA proximity flag | Natural England designated sites dataset |
The screening gives you a defensible, written view on BNG cost provision for the bid model, and on which specialist surveys must be commissioned before submission. See what is included in our 48-hour desktop pack.
What this desktop BNG screening does not replace
The desktop screening does not replace a Phase 1 Habitat Survey with UKHab condition measurements by a CIEEM-registered ecologist; protected species surveys (bats May to September, great crested newt eDNA mid-April to end June, breeding birds March to August, reptiles, badgers), which are seasonal and require site attendance; the formal Statutory Biodiversity Metric submission with chartered ecologist sign-off; BNG monitoring reports at year 5, year 10 and year 30; habitat creation method statement and management plan; off-site units transactions; Section 106 BNG legal agreement drafting; or a formal Habitats Regulations Assessment.
Where any of these are triggered, the report names the specialist study, indicative cost range and typical timeline.
Four packs sized to four small-developer decisions
| Pack | What it does for BNG | Decision moment | Price |
|---|---|---|---|
| Site Appraisal | BNG trigger status, exemption check, indicative habitat baseline | Auction bid, conditional offer, option agreement deadline | From £199, 48 hours |
| Feasibility Intelligence | Adds indicative BNG cost provision (on-site, off-site units or credits) into the bid model | Pre-acquisition or before architect instruction | From £895, 48 hours |
| Pre-Application Pack | Adds full desktop BNG evidence section for pre-app advice | Pre-app meeting booked | From £1,995, 48 hours |
| Planning Intelligence Pack | Submission-ready BNG layer alongside commissioned ecology field survey work | Application submission | Tailored, 48 hours |
The £199 screening typically pays for itself by killing one bad bid before you spend £4k to £8k on architect concept fees.
Send the boundary today
Send postcode, red-line boundary (KML, GeoJSON or a marked-up plan), intended use and indicative dwelling count to the order form. Pay on confirmation. A senior planner reviews the constraint set, a GIS analyst runs the BNG layer, and the report lands in your inbox within 48 hours of confirmed inputs.
What you walk away with: BNG trigger status, exemption position, indicative baseline, indicative 10% target, delivery route options with cost ranges, and the survey trigger list. Enough to bid, walk away, instruct an architect, or book a pre-app with confidence.
For how BNG sits with other constraints, see our guide to reports for planning permission and our development land due diligence guide. For wider statutory context, see GOV.UK planning permission guidance.
Order a Site Appraisal or See a sample report. From £199, delivered in 48 hours.