Wiltshire BNG advice
Biodiversity Net Gain in Wiltshire
Plan your Wiltshire development around local habitat evidence, council policies and nature recovery opportunities.
ACP Consultants can help with habitat surveys, biodiversity metric calculations and a practical BNG delivery plan for your Wiltshire site.
Local planning guidance
How does biodiversity net gain work in Wiltshire?
For planning applications within the statutory framework, the aim is usually to achieve at least a 10% increase in biodiversity value.
An ecologist first identifies the site's existing habitats. An appropriate UKHab survey, condition assessment and statutory metric help establish the baseline. The proposed scheme is then assessed against habitat retention, creation and enhancement.
The calculation is not a measure of the percentage of land left green. Habitat type, area, condition, distinctiveness, strategic significance and delivery risk can all influence the resulting units.
Hedgerows and watercourses have separate unit calculations. Therefore, an increase in grassland area cannot simply cancel out every different loss of woodland, hedgerow or stream habitat.
Early habitat evidence helps designers avoid unnecessary loss and assess whether new habitats can realistically establish and be managed.
For technical methods, see ACP's BNG assessment and habitat baseline surveys and statutory biodiversity metric calculations.
Local planning guidance
Which planning authority applies to your Wiltshire site?
The Wiltshire area contains two unitary planning authorities and a National Park exception.
Wiltshire Council handles most ordinary housing and commercial planning applications in Wiltshire outside the National Park. Swindon Borough Council has its own planning policies and validation process. The New Forest National Park Authority deals with applications inside its legal park boundary.
| Project location | Planning authority | Operative adopted policy | Nature recovery map and important exception |
|---|---|---|---|
| Most Wiltshire sites: Salisbury, Trowbridge, Chippenham, Devizes, Melksham and other land outside the National Park | Wiltshire Council | 2015 Core Strategy CP50/51/52; 2020 Housing Site Allocations and relevant saved/neighbourhood policies | Wiltshire and Swindon LNRS mapped measures. Withdrawn 2020–2038 draft Policy89 20% is NOT adopted |
| Swindon Borough and its rural parishes | Swindon Borough Council | Swindon Local Plan 2026 adopted 2015, EN4 biodiversity | Same published Wiltshire/Swindon LNRS, but different LPA; emerging Swindon Local Plan 2043 is at Reg19 consultation until 12 Nov2026 |
| Wiltshire portion of the New Forest National Park | New Forest National Park Authority | National Park Local Plan 2019, SP5/SP6; local requirements Sept2026 | Wiltshire LNRS applies only to park land inside Wiltshire; Hampshire LNRS to park land in Hampshire. Check boundary and separate protected-site controls |
| Minerals and waste development outside the National Park | Wiltshire Council or Swindon Borough Council according to site | Adopted Wiltshire/Swindon joint minerals and waste plan framework, including 2009 core strategies and 2013 allocations | Separate minerals/waste planning pathway and habitat restoration evidence; confirm LPA and permissions |
| Minerals and waste inside the New Forest National Park | New Forest National Park Authority | Park planning powers include minerals/waste inside the legal boundary | Apply park regulations and relevant territorial LNRS; do not submit to ordinary Wiltshire or Swindon service by assumption |
A Swindon postcode or a reference to a “Wiltshire” location does not by itself prove the planning boundary. Likewise, land in a National Landscape is not automatically within a separate National Park planning jurisdiction.
National Landscapes are not additional planning authorities
Parts of Wiltshire lie within Cranborne Chase, the Cotswolds and North Wessex Downs National Landscapes. Their landscape character and protection may matter for design, but the designation does not create a separate local planning authority.
The legal New Forest National Park boundary is different. Within it, the National Park Authority's adopted plan and validation requirements apply.
Prepare your site brief
Wiltshire BNG: six practical evidence checks
Use these questions to organise your site information, ecological evidence and planning requirements before commissioning an assessment.
| Question | Why it matters | Evidence to prepare |
|---|---|---|
| 1. When was the application made and what permission history exists? | August 2026 new exemptions and non-major hierarchy may not apply to earlier original permissions or certain section 73 variations. | Application date, previous decisions and current government BNG exemption rules. |
| 2. Is a statutory BNG exemption truly available? | A site no larger than 0.2ha qualifies under the new route only with the priority-habitat and application-date conditions met. Householder and de minimis are different tests. | Scaled whole red-line boundary, area, priority habitat and habitat-impact evidence, with stated legal basis. |
| 3. Which habitats or protected features could be affected? | Chalk grassland, Salisbury Plain SPA/SAC, Bath/Bradford bat SAC, ancient woodland, River Avon and New Forest habitats can trigger different evidence. | UKHab survey, habitat condition, designation/impact-pathway check and relevant bat, bird, woodland or river survey if needed. |
| 4. Does the LNRS potential measure match the proposed habitat action? | An ACB is not an automatic metric uplift. New Forest park sides fall in different territorial LNRS areas. | Wiltshire mapped measures, actual polygon, action type, habitat and current statutory metric user guide. |
| 5. Does River Avon SAC nutrient neutrality apply? | Some affected catchment developments require a separate phosphate budget and protected-site mitigation. Nutrient credits are not BNG habitat units. | Natural England River Avon nutrient calculator, drainage/wastewater information, relevant HRA/mitigation evidence. |
| 6. How will habitat gains be delivered and managed? | Major and non-major gain hierarchies differ. Offsite delivery needs habitat trading, registration/allocation, legal agreement and long-term management. | Metric, design options, appropriate HMMP and registered offsite gain site evidence where relevant. |
Bring your red-line plan, proposed works and any existing ecology reports. Discuss your Wiltshire BNG assessment with ACP.
Local planning guidance
The Wiltshire and Swindon Local Nature Recovery Strategy
The Wiltshire and Swindon Local Nature Recovery Strategy (LNRS) was published in 2025. Wiltshire Council is the responsible authority. Swindon Borough Council, New Forest National Park Authority and Natural England supported its preparation.
The strategy area covers Wiltshire, Swindon and relevant Wiltshire-side parts of the New Forest National Park. It provides a shared framework for identifying and connecting priority habitats across the area.
For instance, the strategy considers Wiltshire's chalk grassland, farmland habitats, wetland networks, rivers, woodland and ecological connections. It helps landowners, planners and developers understand where different habitat actions could contribute to wider nature recovery.
How does the Local Habitat Map work?
The LNRS map identifies:
- Areas of Particular Importance for Biodiversity (APIBs): existing important biodiversity sites and mapped irreplaceable habitats.
- Areas that Could Become of Particular Importance for Biodiversity (ACBs): strategic opportunities where nature recovery actions may contribute to priorities.
- Mapped potential measures: suggested habitat creation, restoration or management actions for appropriate locations.
The mapped-measures data was updated by Wiltshire Council in April 2026, providing a useful current starting point for habitat planning.
However, an ACB is not itself a new statutory wildlife designation. Nor does it automatically grant planning permission, establish a habitat bank or increase biodiversity units.
A metric strategic-significance uplift depends on the specific eligible habitat action, mapped potential measure and location. An ecologist should document the source and match before relying on it.
Wiltshire and Swindon LNRS, Wiltshire Council LNRS mapped measures data.
How does the strategy work across the New Forest boundary?
The Wiltshire portion of the New Forest National Park forms part of the Wiltshire and Swindon strategy area. Most of the National Park is in Hampshire and uses the relevant Hampshire LNRS geography.
Therefore, do not apply a Wiltshire mapped potential measure to Hampshire-side land without checking the actual strategy boundary.
The National Park Authority still determines planning applications inside the park. Its planning responsibilities are separate from the organisation that prepared the relevant LNRS.
Local planning guidance
Does your Wiltshire development need mandatory BNG?
Not every planning application is subject to the statutory 10% condition. The relevant exemption depends on the development type, application date, whole red-line site area and any priority habitats affected.
For qualifying planning applications made on or after 6 August 2026, a development on a red-line site of 0.2 hectares or less can be exempt if it does not adversely affect onsite priority habitat.
Other exemptions include genuine householder applications and some developments with very small habitat impacts. A further exemption now covers certain wholly temporary development permitted for five years or less, subject to conditions.
The former specific self-build and custom-build exemption was removed for new applications made from 6 August 2026. Some earlier applications and section 73 variations follow saved arrangements.
A site under 0.2 hectares is not automatically exempt in every circumstance. It must meet all relevant legal tests.
Moreover, an exemption from statutory BNG does not remove protected species, designated-site, tree or nutrient-neutrality duties. These must be assessed independently where they arise.
For examples and detailed eligibility rules, see ACP's BNG exemptions guide and the current government exemptions guidance.
Local planning guidance
Wiltshire Council: the adopted Core Strategy and the withdrawn 20% proposal
The Wiltshire Core Strategy, adopted in January 2015, remains an important part of the current development plan.
Its relevant policies include Core Policy 50, Biodiversity and Geodiversity, Core Policy 51, Landscape, and Core Policy 52, Green Infrastructure.
These policies help protect important habitats, species, natural features and ecological networks. They also support the retention and enhancement of connected green infrastructure.
The Wiltshire Housing Site Allocations Plan, adopted in February 2020, and any applicable saved policies or made neighbourhood plan may add site-specific requirements.
Is 20% biodiversity net gain compulsory across Wiltshire?
The withdrawn draft policy does not establish a county-wide 20% BNG requirement.
The earlier Wiltshire Local Plan Review 2020–2038 proposed Policy 89, which sought at least 20% BNG. The council produced supporting evidence for that proposal.
However, Wiltshire Council resolved to withdraw that draft plan in May 2026, and its independent examination closed. Therefore, the withdrawn draft Policy 89 must not be presented as an adopted statutory or local-plan requirement.
The national 10% objective remains the baseline for in-scope development. Any genuinely adopted site-specific policy or other ecological obligation still needs assessment.
What is happening with the replacement Local Plan?
Wiltshire Council began preparing another Local Plan under the new 2026 plan-making framework.
After a September scoping consultation, the council passed Gateway 1 on 31 October 2026. This established readiness to begin the new formal plan-preparation process.
Gateway 1 does not adopt a new spatial plan or biodiversity percentage. As at 7 November 2026, the 2015 Core Strategy and other operative adopted policies remain the applicable policy starting point.
Wiltshire Council Local Plan, withdrawn plan examination update, Wiltshire Core Strategy.
Local planning guidance
Swindon Borough Council: adopted EN4 and the emerging Local Plan 2043
Swindon has its own adopted planning policies, even though it shares the Wiltshire and Swindon LNRS.
The Swindon Local Plan 2026 was adopted on 26 March 2015. Its Policy EN4, Biodiversity and Geodiversity, seeks to avoid unacceptable impacts and enhance biodiversity where appropriate.
The borough is preparing a replacement Swindon Local Plan 2043. Its Regulation 19 Proposed Submission consultation opened on 24 September 2026.
As of 7 November 2026, the consultation remains open until 11:59 pm on 12 November 2026. The council has not yet submitted and adopted the replacement plan.
Therefore, applicants should use the adopted 2015 plan for current policy, while checking the status of emerging proposals and relevant site allocations.
What BNG information does Swindon request?
Swindon's published biodiversity guidance sets out the national initial application information. It includes a statement about whether BNG applies, baseline habitat value and completed metric, any relevant degradation history and a scaled habitat plan.
The council also requests suitable Excel metric information, and it may ask for supporting habitat condition or gain-hierarchy evidence where relevant.
Apply the August 2026 national gain hierarchy for qualifying non-major applications when considering onsite and registered off-site delivery.
The formal Biodiversity Gain Plan is normally approved after planning permission and before development begins.
Swindon adopted Local Plan, Swindon Local Plan 2043, Swindon BNG application guidance.
Local planning guidance
New Forest National Park: Wiltshire's separate planning authority
A small part of Wiltshire falls inside the New Forest National Park. For development there, the New Forest National Park Authority is the statutory local planning authority.
Its Local Plan 2016–2036, adopted in August 2019, contains SP5, Nature Conservation Sites of International Importance, and SP6, The Natural Environment.
These policies can affect proposed habitat loss, ecological networks, protected species and impacts on designated sites.
The National Park also has its own local planning validation requirements, last published on 1 September 2026. These include relevant ecology, biodiversity metric, habitat condition, designated-site and supporting survey information.
A small or statutory BNG-exempt proposal can still need other ecology evidence. Likewise, purchasing BNG units does not resolve separate New Forest protected-site mitigation.
Before submitting an application, confirm the actual park boundary and follow the National Park Authority's application requirements rather than those for ordinary Wiltshire Council land.
New Forest National Park planning policy, September 2026 local requirements.
Local planning guidance
Planning validation: what BNG evidence should you prepare?
A planning application subject to BNG generally needs the national minimum information about the pre-development habitat baseline. However, local authorities may ask for proportionate additional ecology details.
Wiltshire Council publishes an application validation checklist and biodiversity-development guidance. Its ecological assessment requirement depends on the nature and location of the proposal. The guidance includes questions on protected species, habitats, BNG and nutrient neutrality.
Swindon Borough Council publishes biodiversity guidance requiring an appropriate metric and initial baseline information. It may request additional design-stage evidence for the proposed gain route.
New Forest National Park Authority has its own September 2026 validation list, with habitat condition and designated-site survey requirements where relevant.
The exact local checklist is not identical in all three areas. Therefore, match the documents to the actual LPA, application category and sensitive habitats.
The formal statutory Biodiversity Gain Plan is normally approved after planning permission and before commencement. It is different from the initial BNG statement, baseline metric and explanatory habitat strategy.
Local planning guidance
Ecological constraints in Wiltshire that BNG does not replace
Wiltshire has distinctive protected habitats and species. A BNG metric result is useful, but it is not permission to harm designated sites or protected wildlife.
Salisbury Plain: chalk grassland and stone-curlew
Salisbury Plain SAC supports extensive chalk grassland and other important habitats, including juniper and marsh fritillary. The broader Plain also includes a designated Special Protection Area (SPA) of importance for birds.
Stone-curlew breeding habitat and recreational disturbance can require separate assessment or mitigation where a proposal has a relevant impact pathway.
Therefore, habitat creation in a landscape like Salisbury Plain must consider the existing grassland and bird interests. Generic amenity planting may not be a suitable substitute.
Bath and Bradford-on-Avon Bats SAC
The Bath and Bradford-on-Avon Bats SAC includes important greater and lesser horseshoe bat interests and other qualifying bat features.
Projects near relevant bat habitat may need survey evidence, sensitive lighting, habitat connectivity and protected species considerations.
Statutory BNG can support habitat enhancement. However, it does not replace a bat licence, designated-site assessment or the protection of roosts.
River Avon SAC and Wiltshire's chalk streams
The River Avon SAC is an internationally important river system with protected watercourse habitat and aquatic species.
Development near affected river systems may need assessments of water quality, drainage, nutrient impacts or watercourse management. The statutory metric also accounts for watercourse units separately from area and hedgerow units.
Other habitats across Wiltshire include ancient woodland, veteran trees, wet meadows, farmland hedges and chalk grassland. The actual surveys depend on the site.
Authoritative sources: [Salisbury Plain SAC, Bath and Bradford-on-Avon Bats SAC, River Avon SAC.]
Local planning guidance
River Avon nutrient neutrality is separate from BNG
Some developments within the River Avon (Hampshire) SAC catchment may face separate phosphorus-related planning requirements.
Wiltshire Council has published a nutrient neutrality strategy for the catchment. Natural England also provides a specific River Avon SAC nutrient neutrality calculator.
Depending on the application and drainage pathway, the planning authority may need a Habitats Regulations Assessment and suitable phosphate mitigation.
This assessment is not the statutory BNG metric. A phosphate-mitigation credit and a biodiversity unit are different environmental measures.
For example, a project could achieve its biodiversity net gain but still require phosphorus mitigation. Conversely, an applicant with a BNG exemption might still need to consider protected-site water-quality impacts.
The catchment, development type, existing permission and wastewater arrangements all matter. Do not assume every Wiltshire site needs nutrient credits, or that a local scheme has available credits at a fixed price.
Natural England River Avon nutrient neutrality calculator, Wiltshire Council River Avon catchment guide.
Local planning guidance
Six practical stages for a Wiltshire BNG assessment
1. Confirm the correct authority and development category
Check the red-line boundary and whether the site is in Wiltshire Council, Swindon Borough or the New Forest National Park. Record the application date and any earlier permission history.
2. Check BNG exemptions and independent ecological duties
Establish whether statutory BNG applies. Record the legal basis for any exemption. Identify protected habitats, species and potential River Avon nutrient constraints.
3. Survey and map the existing habitats
Arrange suitable UKHab mapping and condition assessment. Include relevant hedgerows and watercourses. Obtain additional ecological records or field surveys when the site's constraints require them.
4. Apply the correct current metric and LNRS measure
Use the appropriate statutory biodiversity metric or an eligible Small Sites Metric. The most recent statutory workbook is version 1.1.0, updated 3 November 2026.
Previously published statutory metric versions remain permitted under current guidance. A metric uplift from the LNRS must be justified by the matching mapped potential measure.
5. Test realistic habitat options
Prioritise avoiding unnecessary loss. Assess onsite retention, creation and enhancement. Where appropriate, investigate compatible registered off-site units and the metric's habitat trading and spatial rules.
6. Plan the Biodiversity Gain Plan and habitat management
For an in-scope planning permission, obtain approval of the formal Biodiversity Gain Plan before starting development.
Significant onsite and registered off-site gains normally require legally secured habitat management for at least 30 years, with appropriate monitoring responsibility.
For further assistance, see ACP's Biodiversity Gain Plan guidance and Habitat Management and Monitoring Plans.
Local planning guidance
On-site delivery, off-site units and the gain hierarchy
BNG should be approached as a practical ecological delivery problem, not simply a target percentage.
For major development, avoidance and suitable onsite habitat measures generally take priority before registered off-site gain. Statutory biodiversity credits remain the final option.
For qualifying non-major applications made on or after 6 August 2026, onsite habitat enhancement, onsite habitat creation and registered off-site delivery share an equal priority level under the revised hierarchy. Credits remain last.
An off-site gain site needs appropriate legal security, biodiversity-unit registration and formal allocation to the development. Habitat trading and geographic considerations must also be satisfied.
A New Forest habitat-bank scheme, a Wiltshire LNRS opportunity area or a local landowner's proposal is not automatically proof that matching units are registered, saleable or allocated.
Likewise, phosphorus mitigation credits for the River Avon are not biodiversity units. The two obligations should be assessed separately.
See ACP's off-site biodiversity units guide and the government biodiversity gain sites register for more information.
Local planning guidance
Wiltshire BNG application checklist
Unsure what ecology evidence your Wiltshire application needs?
Send us the site location, proposed works, plans and any existing ecological information. ACP can help identify a proportionate BNG assessment and planning evidence route.
Local planning guidance
How ACP Consultants can support your Wiltshire project
A suitable BNG assessment should help the project team make better decisions early, rather than leave habitat calculations until the final planning submission.
ACP can help scope the ecological baseline, interpret statutory biodiversity metric results and compare practical habitat delivery options.
Where bats, designated sites, sensitive grasslands or River Avon nutrients may matter, those issues need the appropriate separate ecological assessment.
The right scope follows the actual site, planning authority, development type and programme. Not every Wiltshire proposal requires the same survey effort.
For a wider explanation, see ACP's BNG process guide and BNG consultant services.
Local planning guidance
Frequently asked questions about BNG in Wiltshire
Is statutory biodiversity net gain compulsory for every Wiltshire development?
No. The statutory condition generally applies to qualifying planning permissions, subject to exemptions and transitional arrangements. Check the development category, date, red-line area and priority habitats.
Does Wiltshire Council require 20% BNG?
A 20% target appeared in Policy 89 of the former draft Wiltshire Local Plan Review. However, that plan was withdrawn in May 2026. The draft policy is not an adopted blanket requirement. The statutory minimum for in-scope development is normally 10%.
What Wiltshire Local Plan is currently adopted?
The Wiltshire Core Strategy adopted January 2015 remains operative, including CP50, CP51 and CP52. The Housing Site Allocations Plan adopted February 2020 and relevant saved or neighbourhood policies may also apply.
Does the Wiltshire and Swindon LNRS include Swindon?
Yes. It is a shared published strategy prepared by Wiltshire Council with Swindon and other supporting authorities. Swindon nevertheless has its own planning authority and adopted Local Plan.
Does the LNRS apply to the Wiltshire part of New Forest National Park?
Yes, where the park land falls within Wiltshire's strategy area. Most of the National Park lies in Hampshire and follows the appropriate Hampshire strategy geography. The Park Authority remains its own planning authority.
Can a development of 0.2 hectares or less be exempt from statutory BNG?
For qualifying applications made on or after 6 August 2026, the new exemption can apply where the whole red-line site is no larger than 0.2 hectares and onsite priority habitat is not adversely affected. Saved permissions and other conditions need separate review.
Are self-build homes automatically exempt from BNG?
No. The former specific self-build and custom-build exemption was removed for new planning applications from 6 August 2026. Another legal exemption could apply if its distinct conditions are met.
What BNG policy applies to a Swindon development?
Swindon Local Plan 2026, adopted March 2015, remains the operative plan and includes EN4 Biodiversity and Geodiversity. Its proposed Local Plan 2043 is at Regulation 19 consultation stage as of 7 November 2026, not adopted.
Will the LNRS map automatically increase the biodiversity metric score?
No. A suitable proposed habitat measure must match the eligible mapped potential measure, location and current metric rules. Simply being inside an LNRS opportunity area does not automatically award more units.
Does achieving 10% BNG remove the need for bat surveys or protected-site mitigation?
No. Salisbury Plain, Bath and Bradford-on-Avon Bats SAC, River Avon SAC and other habitats or species may require separate evidence, mitigation or licensing based on the actual impact pathway.
Are River Avon phosphorus credits the same as off-site biodiversity units?
No. Nutrient mitigation credits address phosphorus effects on a protected water catchment, whereas BNG units measure habitat biodiversity value. A project may need both, and each has its own rules and evidence.
What information should I send ACP for a Wiltshire BNG quotation?
Send the site location or red-line plan, description of proposed works, current drawings, application stage, planning authority and existing ecology reports. Known bat or River Avon constraints also help establish the scope.
Local planning guidance
Discuss biodiversity net gain for your Wiltshire development
If you are preparing a planning application, reviewing habitat surveys or exploring onsite and off-site gain delivery, start by confirming the site and proposal.
Tell ACP about your Wiltshire development. We can help identify the likely BNG assessment, ecological constraints and next steps.
Talk to ACP / Site enquiries
What does your site need next?
Tell us where the site is, what you plan to build and how far the application has progressed. We’ll use that context to discuss the surveys, calculations or plans your project needs.
What to have to handA red-line plan, an existing ecology report or a request from the council can help us scope the work. Start with whatever you already have.
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Wiltshire BNG
Sources and references
Reviewed 7 November 2026.
Official planning and nature recovery sources
- GOV.UK BNG planning guidance
- GOV.UK BNG exemptions
- Statutory biodiversity metric tools and guidance
- Wiltshire and Swindon LNRS
- Wiltshire Council LNRS mapped measures
- Wiltshire Core Strategy
- Wiltshire Local Plan examination withdrawal
- Swindon Local Plan 2026
- Swindon Local Plan 2043
- Swindon BNG validation guidance
- New Forest National Park local planning requirements September 2026
- Salisbury Plain SAC
- Bath and Bradford-on-Avon Bats SAC
- River Avon SAC
- Natural England River Avon nutrient neutrality calculator
- Government biodiversity gain sites register