Cornwall BNG advice
Biodiversity Net Gain in Cornwall
Plan your Cornwall development around local habitat evidence, adopted biodiversity policies and nature recovery opportunities.
ACP Consultants can help with habitat surveys, biodiversity metric calculations and a practical BNG delivery plan for your Cornwall site.
Local planning guidance
Which authority and planning policies apply in Cornwall?
For sites on mainland Cornwall, Cornwall Council is the ordinary local planning authority. Former district council names are geographical references, not separate planning authorities.
However, the Council of the Isles of Scilly is an independent planning authority with its own adopted Local Plan and validation guidance. The Isles share a nature recovery strategy with Cornwall, but not the same development plan.
For a mainland site, check the adopted Cornwall Local Plan, its later development plan documents and any relevant neighbourhood plan. The true red-line boundary determines which designations and allocations apply.
Cornwall Council’s adopted biodiversity policies
| Current adopted policy | What it means for a development |
|---|---|
| Cornwall Local Plan 2010–2030, adopted 2016: Policy 23 Natural Environment | Protects and considers natural habitats, ecological networks, ancient woodland and veteran trees. |
| Policy 22 European Protected Sites | Requires appropriate protection and mitigation where development could affect relevant European nature conservation sites. |
| Policy 25 Green Infrastructure | Supports green infrastructure, habitat connections and appropriate trees and landscaping. |
| Climate Emergency DPD, adopted February 2023: Policy G2 Biodiversity Net Gain | Requires a minimum 10% BNG for non-exempt development, read alongside current national exemptions and the statutory metric. |
| Climate Emergency DPD: Policy G3 Canopy | Expects major development to provide at least 15% tree canopy coverage, subject to the policy's exclusions and justified alternatives. This is not an extra 15% BNG target. |
| Climate Emergency DPD: Policies G1 and G4 | Address green infrastructure and the local nature recovery network, including ecological connections. |
The adopted Local Plan also includes the 2019 Site Allocations DPD, the 2018 Minerals Safeguarding DPD and other applicable plans. These can affect the site design and existing land obligations.
Is the new Cornwall Local Plan 2050 already adopted?
No. Cornwall Council is preparing a new Local Plan 2050. Its scoping consultation runs from 5 October to 16 November 2026.
The consultation invites views on the plan's scope, vision and evidence. It has not created a replacement adopted biodiversity policy.
Therefore, applicants should continue to use the operative adopted plan and current planning validation list, while checking whether emerging proposals are relevant to their project.
What changes for a development on the Isles of Scilly?
The Council of the Isles of Scilly adopted its Local Plan 2015–2030 on 25 March 2021. This includes island-specific environmental policies and planning maps.
The island council publishes its own Biodiversity Net Gain application guidance. In relevant cases, it requests a biodiversity metric in Excel format and a Gain Plan in PDF format.
Those requirements should be checked with the island council. Cornwall Council's G2, G3 and local BNG Statement should not automatically be applied to an Isles of Scilly application.
Cornwall BNG: choose the correct planning and ecology route
Work through these five checks using your actual red-line site boundary. Each check directs you to relevant official information.
1. Is the development in Cornwall or on the Isles of Scilly?
Mainland Cornwall: Cornwall Council is the planning authority. Read the adopted Cornwall Local Plan documents and current local validation requirements.
Isles of Scilly: the Council of the Isles of Scilly is a different planning authority with its own adopted 2021 Local Plan and own BNG planning guidance. Cornwall's G2/G3 and local major BNG Statement are not automatically Scilly requirements.
Both areas share the Cornwall and Isles of Scilly nature recovery strategy, but not one planning council.
2. Which adopted policies and planning-stage documents apply?
For mainland development, consider the Cornwall Local Plan 2016, Site Allocations DPD 2019, Minerals Safeguarding DPD 2018, relevant neighbourhood policy and the adopted 2023 Climate Emergency DPD.
G2 addresses BNG; G3 normally expects at least 15% tree canopy coverage on major schemes, subject to its conditions. The canopy target is not 15% biodiversity net gain. G4 addresses local nature recovery networks.
The Cornwall Local Plan 2050 consultation runs from 5 October to 16 November 2026 and is not an adopted replacement.
3. Is mandatory BNG relevant, and which application evidence is needed?
Check the planning application date, type, complete red-line area and effects on any on-site priority habitat. For qualifying applications made from 6 August 2026, a site no larger than 0.2 hectares may be exempt from statutory BNG where no on-site priority habitat is impacted. Other exemption and transitional criteria must be checked separately.
Read the current GOV.UK exemption rules. Do not rely on the former general new self-build/custom-build exemption.
For mainland projects, Cornwall Council's current BNG guidance sets national baseline evidence requirements and a separate additional BNG Statement for major applications where relevant. Use an appropriate statutory metric workbook in a macro-disabled .xlsx file with visible sheets. A statutory Biodiversity Gain Plan must be approved before commencement where the gain condition applies.
4. Does the published nature recovery network support your habitat proposal?
Use the published Cornwall and Isles of Scilly LNRS and current map. Zone 1 identifies the Existing Nature Network; Zone 2 identifies Opportunity Areas. Scilly mapping reflects its smaller island landscapes.
Compare any mapped measure with the actual UKHab/condition survey, soils, hydrology, landowner control and deliverable management. Only assign strategic significance under the appropriate statutory metric when the location and proposed habitat genuinely match relevant published measures.
An opportunity-zone location is not proof of a registered gain site, saleable unit, permission or automatic uplift.
5. Are nutrient or protected-site obligations separate from BNG?
For an affected site in the River Camel nutrient catchment, use the revised February 2026 boundary and Cornwall Council phosphate guidance and October 2026 calculator v5. Check actual wastewater routing and necessary mitigation rather than assuming every Cornwall development is affected.
Check European Sites Mitigation and any protected species/habitat, tree, minerals restoration or water consent separately. Phosphate credits and protected-site mitigation are not interchangeable with registered biodiversity units.
If off-site BNG is needed, consult Cornwall Council habitat-bank information and verify actual unit registration and allocation through the national gain-sites register. Significant gains generally need management for at least 30 years.
Need a project-specific scope? Share your red-line plan, planning authority, proposed works, application stage and any ecology or nutrient correspondence.
Local planning guidance
What biodiversity information does Cornwall Council expect with a planning application?
Cornwall Council's BNG guidance, updated in August 2026, separates the national minimum information from a local BNG Statement for major development.
For an applicable statutory BNG application, applicants should provide the relevant baseline information. This generally includes the pre-development biodiversity value, the metric workbook and version, a scaled habitat plan, and any relevant earlier-date or habitat-degradation evidence.
The council also asks applicants who claim an exemption to explain and substantiate it. Writing “de minimis” on a form without evidence may lead to the application being invalid.
What is Cornwall's additional BNG Statement?
For major development, Cornwall Council normally expects a local BNG Statement providing information such as:
- The proposed post-development habitats and corresponding metric calculation.
- Any likely off-site biodiversity units or statutory credits and the reason they may be needed.
- Significant on-site habitat enhancement proposals and supporting plans.
- A draft Habitat Management and Monitoring Plan, where relevant.
- Proposed legal arrangements or section 106 heads of terms, where required.
The timing can differ for outline applications and reserved matters. For example, where landscaping or layout is being approved, the local Statement may be requested at that stage.
For ordinary statutory permissions, the final Biodiversity Gain Plan requires approval before development commences. A draft at application stage can help identify issues, but that is different from final pre-commencement approval.
How should the statutory metric be submitted?
Cornwall Council says the metric workbook should be saved as a macro-disabled Excel file (.xlsx), with all sheets visible and a file size below 10 MB.
The correct metric, habitat plans and supporting evidence must agree with each other. Avoid using an old pre-statutory Metric 4.0 workbook for new mandatory BNG work.
Always check the latest Cornwall Council BNG planning requirements before submission.
Local planning guidance
Does every Cornwall development need 10% BNG?
No. The statutory framework includes exemptions and transitional rules.
From 6 August 2026, a qualifying planning application on a red-line development site of 0.2 hectares or less may be exempt if the works do not affect any on-site priority habitat.
There are also separate exemptions for qualifying householder development, negligible habitat impacts and certain temporary proposals. However, new self-build and custom-build applications no longer have their former general exemption from that date.
These rules depend on the actual application, site boundary, proposal and timing. Earlier applications and some section 73 cases may retain different treatment.
Does BNG exemption mean no ecology report is needed?
Not necessarily. Statutory BNG exemption does not remove local planning policy, protected-species duties, designated-site safeguards or other relevant ecological assessment.
For example, a small Cornwall site may still have trees, hedgerows, bats, protected heathland or a water-related planning constraint.
It is sensible to review the actual works and habitat impacts before assuming an exemption resolves all environmental requirements.
How does the Small Sites Metric differ from an exemption?
The Small Sites Metric is a simplified calculation method available only to eligible proposals that still need a BNG calculation.
A statutory exemption means the mandatory BNG condition does not apply. Being a small site does not automatically make the simplified metric appropriate.
Where habitats or protected features make the scheme ineligible for the Small Sites Metric, the full statutory tool may be required.
Local planning guidance
Which biodiversity metric is current?
The current official Statutory Biodiversity Metric was updated to version 1.1.0 on 3 November 2026. Government guidance also permits earlier valid statutory versions in appropriate cases.
The November update clarified how watercourse spatial risk applies to projects spanning multiple waterbody catchments. It was not a blanket change to habitat unit outputs.
The metric calculates area habitats, hedgerows and watercourses as separate categories. A surplus in one category cannot simply cancel a deficit in another.
A reliable baseline survey, habitat-condition evidence and the proposed landscape design should support the calculation. In turn, the calculation should help inform better design decisions.
For method-specific support, read our Statutory Biodiversity Metric guidance and Small Sites Metric guide.
Local planning guidance
Cornwall's 15% tree canopy policy is separate from BNG
Cornwall's adopted Climate Emergency DPD Policy G3 expects major development to deliver at least 15% canopy coverage across the relevant site area, excluding priority habitat areas.
The policy considers retained trees and suitable new canopy. It also permits a justified alternative percentage where the specified ecological, landscape, heritage or operational circumstances support one.
The canopy proposal should use the Cornwall Council-approved canopy calculator and account for the trees' long-term growth and maintenance.
Importantly, 15% tree canopy is not 15% biodiversity net gain. The canopy calculation and statutory metric are different assessments, even though tree habitats may contribute biodiversity units.
For smaller proposals, the 15% canopy target does not apply in the same way. Nevertheless, existing trees and green infrastructure may still need protection under other planning policies.
Early coordination of arboriculture, ecology and landscape design can help avoid conflicting commitments.
Local planning guidance
Cornwall and Isles of Scilly Local Nature Recovery Strategy
The Cornwall and Isles of Scilly Local Nature Recovery Strategy (LNRS) was published in March 2025. Cornwall Council led the work with the Council of the Isles of Scilly, Natural England and local partners.
It sets out priorities for healthier habitats and better ecological connections across mainland Cornwall and the islands.
The strategy supports improvements to woodland, farmland, coastal habitats, heathland, wetlands, rivers and wildlife-rich towns. It also provides a Nature Recovery Network map that can help identify the right kind of habitat action in the right place.
The map offers useful evidence for nature recovery planning. However, it is not permission to create a habitat, a register of biodiversity units or an automatic increase in the statutory metric score.
What do Zone 1 and Zone 2 mean?
The published Nature Recovery Network mapping uses two principal zones:
- Zone 1 — Existing Nature Network. Existing habitats and areas of importance for nature. These should be protected and enhanced appropriately.
- Zone 2 — Opportunity Areas. Places with potential for suitable habitat creation and restoration, informed by the strategy's priorities.
The Isles of Scilly opportunity mapping was developed with its smaller island landscapes in mind. Therefore, site-specific mapping should use the correct part of the shared strategy.
How to use the Nature Recovery Network map for BNG
- Locate the site using the actual red-line boundary and the current official map.
- Identify the relevant zone and mapped measures, rather than relying on the colour alone.
- Read the written strategy, including the habitat priority and proposed activity that may relate to the site.
- Check ecological feasibility through a current habitat survey, soils, hydrology and long-term management.
- Record the evidence where the statutory metric's strategic significance is being considered.
A Zone 2 location does not necessarily mean a proposed woodland, pond or meadow would be suitable. Equally, land outside a particular mapped opportunity may still contain valuable habitats needing protection.
Explore the Cornwall and Isles of Scilly Nature Recovery Strategy.
Local planning guidance
Cornwall habitats and ecological constraints to consider
Cornwall's landscapes support different habitats and protected features. Consequently, a good BNG design starts with the actual site rather than a generic selection of new planting.
Cornish hedgebanks, farmland and grassland
Traditional field boundaries, hedgebanks, meadows and farmland habitats can provide valuable ecological connections. The condition of existing features can affect both site design and the statutory metric.
Where new grassland is proposed, suitable soils, management and realistic establishment are essential. Nature-friendly farmland measures should not be chosen solely because a map lists a broad opportunity.
Heathland, moorland and former mining landscapes
Cornwall has heathland, mires, scrub and historic mining or china-clay landscapes. Some former industrial land supports valuable wildlife habitats.
Restoration can offer benefits, but existing ecological and minerals-restoration obligations must be identified. The creation of additional BNG cannot simply replace work already legally required.
Rivers, wetlands and estuaries
River valleys and wetlands can offer opportunities for habitat connections and more natural flood management.
However, the River Camel, its tributaries and other watercourses may also raise protected-site and water-quality questions. Watercourse metric units require their own evidence and cannot be substituted freely for area habitat units.
Coasts, woodland and urban green infrastructure
Coastal heath, maritime grasslands, dunes, cliffs, wooded valleys and urban parks all have different restoration needs.
For example, a coastal planting proposal may be constrained by salt exposure or erosion, while urban trees require suitable rooting space and long-term care. Protected species and designated sites must be assessed separately.
Local planning guidance
River Camel phosphate neutrality is not the same as BNG
Some planning proposals within the River Camel catchment must address phosphate pollution as well as biodiversity net gain.
Natural England revised the affected catchment boundary in February 2026. Cornwall Council then updated its mapping and guidance, with version 5 of its phosphate budget calculator published in October 2026.
The rules depend on the actual site's drainage and the revised catchment. Therefore, a postcode or the old mapped boundary is not sufficient to determine whether phosphate mitigation is needed.
What might a development need to provide?
For an affected proposal, the council may require a phosphate budget, supporting evidence and appropriate nutrient-neutral mitigation.
The relevant calculation considers nutrient loading and potential effects on the protected River Camel Special Area of Conservation.
Cornwall Council's mitigation framework can assess nutrient effects over 80 years. This differs from the at least 30-year management normally required for significant statutory BNG habitat gains.
Phosphate mitigation credits are not biodiversity units. They serve different legal purposes and must be accounted for separately.
For an affected site, use the current Cornwall Council nutrient-neutrality and phosphate calculator guidance.
Local planning guidance
European protected sites and recreational mitigation in Cornwall
Some Cornish sites may also need an assessment under the Habitats Regulations.
Cornwall Council's adopted European Sites Mitigation Supplementary Planning Document addresses relevant recreational impacts on protected areas such as Fal and Helford and the Plymouth and Tamar estuaries.
The council updated its approach to Penhale Dunes from 12 December 2025. New visitor-mitigation contributions are no longer generally requested there, except for proposals involving more than 500 dwellings within 2.5 kilometres, according to the published council advice.
These requirements depend on the protected-site boundary, the type of development and the current planning advice. Do not assume that every site in Cornwall pays the same contribution.
Measures legally required to protect an internationally designated site cannot automatically be treated as additional BNG units.
For a project in an affected area, review the Cornwall European Sites Mitigation SPD alongside the site-specific ecological advice.
Local planning guidance
On-site habitats, off-site biodiversity units and 30-year delivery
BNG works best when valuable existing habitats are considered before the design is fixed.
First, assess opportunities to retain habitats. Then test feasible habitat enhancement and creation within the development boundary.
Where a shortfall remains, appropriately registered off-site biodiversity units may help meet the statutory objective, subject to the relevant hierarchy and trading rules.
For qualifying non-major applications made from 6 August 2026, on-site creation or enhancement and registered off-site gains can be considered at the same level of preference. Major schemes and older applications can follow a different hierarchy.
Statutory biodiversity credits are distinct and remain a last-resort option.
Can Cornish landowners establish habitat banks?
Potentially. Cornwall Council publishes a process for establishing habitat banks. It includes ecological review, legal securing, subsequent registration and monitoring.
However, a proposed habitat bank is not automatically a registered gain site with units available for sale.
A genuine off-site gain site needs appropriate baseline surveys, realistic habitat creation and management plans, legal commitments, registration and allocation to the development using the units.
The LNRS can help identify ecological opportunities. Nevertheless, the site must still meet the correct metric, location, habitat trading and delivery rules.
What does long-term management involve?
Significant on-site and registered off-site habitat gains generally need at least 30 years of legally secured management.
A Habitat Management and Monitoring Plan (HMMP) can define target habitats, establishment, maintenance, monitoring, responsibility and corrective actions.
The plan should be realistic about soils, water, access and costs. A favourable metric result alone does not establish that a particular habitat will succeed.
For further help, see our off-site biodiversity units guidance and Habitat Management and Monitoring Plan service.
Local planning guidance
Cornwall BNG planning checklist
Use this checklist to organise a proportionate planning submission. It is a preparation guide, not a statutory exemption decision or validation certificate.
The purpose is to identify the right evidence for the right planning question, not produce every possible technical report for every site.
Local planning guidance
How ACP can help with Cornwall BNG projects
1. Confirm the correct requirements
We review the site location, application type, planning stage and available information. First, we help identify which ecological and BNG questions need answering, including any relevant Cornwall-specific validation.
2. Assess the habitats and coordinate the design
Where instructed, the agreed scope may include habitat mapping, condition assessment, statutory biodiversity metric calculations and reporting. We can help the design team review retention, creation and enhancement options.
3. Prepare evidence for delivery
The work may also include a BNG report, Biodiversity Gain Plan information or a Habitat Management and Monitoring Plan. Where a site needs separate nutrient or European-site mitigation, those requirements should be identified and addressed appropriately.
Need clarity on a Cornwall biodiversity net gain requirement?
Send your red-line plan, proposed works, application stage and any ecological or council correspondence. We can help define a proportionate next step without assuming every site needs the same reports.
Request a Cornwall BNG scope review
For a coordinated submission, see our BNG report for planning and Biodiversity Gain Plan guidance.
Local planning guidance
Cornwall biodiversity net gain FAQs
Which council decides biodiversity net gain applications in Cornwall?
Cornwall Council decides ordinary planning applications on mainland Cornwall. The Council of the Isles of Scilly is a separate planning authority for the islands. Both share the Cornwall and Isles of Scilly Local Nature Recovery Strategy, but they have different adopted Local Plans and validation guidance.
What is Cornwall Council's adopted biodiversity net gain policy?
The Climate Emergency DPD Policy G2, adopted in February 2023, sets out a minimum 10% BNG for non-exempt proposals, read with current national law. The 2016 Cornwall Local Plan also includes Policy 23 Natural Environment and Policy 25 Green Infrastructure.
Is Cornwall's tree canopy target an additional 15% BNG requirement?
No. Policy G3 normally expects at least 15% tree-canopy coverage for major development, subject to its exclusions and justified alternatives. That is a separate canopy coverage measure, not a statutory biodiversity-unit percentage. Tree habitats may contribute to BNG where correctly assessed.
Does Cornwall Council need a BNG Statement with every application?
The council's additional local BNG Statement is directed at major applications. It can include post-development metric data, significant gains, off-site rationale, draft management plans and legal proposals. National Article 7 information may be required for other in-scope applications. Check the actual planning class and council validation list.
Are sites of 0.2 hectares or less exempt from BNG?
A qualifying application made on or after 6 August 2026 for a red-line development site of 0.2 hectares or less may be exempt if the proposal does not impact on-site priority habitat. Other conditions and transitional rules still apply. Ecological surveys and protected-site duties may remain necessary.
Are new self-build homes automatically exempt from BNG?
No. The previous general self-build and custom-build exemption does not apply to new applications made from 6 August 2026. Earlier applications can be subject to different transitional rules. Check whether another exemption applies on its own terms.
Has the Cornwall and Isles of Scilly Local Nature Recovery Strategy been published?
Yes. It was published in March 2025 and appears in the GOV.UK register as area 41. Cornwall Council leads the strategy with support from the Council of the Isles of Scilly and Natural England. The strategy contains a written recovery plan and Nature Recovery Network maps.
What do Zone 1 and Zone 2 on the Cornwall nature recovery map mean?
Zone 1 identifies the Existing Nature Network for appropriate protection and enhancement. Zone 2 identifies Opportunity Areas for potential creation and restoration. The correct mapped measures must still be matched to a site's habitats and statutory metric rules. Neither zone automatically registers biodiversity units.
Do River Camel phosphate-neutrality rules apply throughout Cornwall?
No. They relate to the affected River Camel catchment and relevant development. Natural England revised the affected area in February 2026, and Cornwall Council updated the phosphate calculator to version 5 in October 2026. Check actual site and wastewater routing using current mapping.
Are River Camel phosphate credits the same as biodiversity units?
No. Phosphate credits address a separate nutrient-neutrality requirement under protected-site planning rules. Registered biodiversity units address statutory habitat gains. The council's River Camel nutrient mitigation model can cover 80 years, whereas significant statutory BNG gains are generally secured for at least 30 years.
Can I buy biodiversity units from a Cornwall habitat bank?
Potentially, but a habitat bank must have the appropriate legal securing, official registration and genuine units available for allocation. Cornwall Council publishes a landowner establishment process, but that is not itself proof of current stock, habitat type, allocation or price. Check the national gain-site register for the particular project.
When is a Biodiversity Gain Plan approved?
For permission subject to the statutory biodiversity gain condition, the Biodiversity Gain Plan must normally be approved before development starts. Cornwall Council encourages early draft information and has separate application-stage requirements. A national gain plan, a local major BNG Statement and a habitat management plan are not interchangeable documents.
Cornwall BNG
Sources and references
Reviewed 7 November 2026.
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