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Hampshire BNG / County planning guidance

Biodiversity Net Gain in Hampshire

Biodiversity net gain in Hampshire starts with your site boundary, habitat baseline and planning authority. Use this guide to identify the right council, explore the nature recovery map and prepare the evidence your application needs.

ACP helps developers, architects, planners and landowners assess habitats, calculate biodiversity units and plan delivery. We connect the site evidence with local policy, National Park requirements and the wider ecology constraints.

Discuss your Hampshire project →Check the BNG planning steps

Reviewed 7 November 2026 · Hampshire LNRS published 8 December 2025

10% statutory objective / habitat evidence / metric methods

How biodiversity net gain works in Hampshire

For developments in scope, the statutory objective is to increase biodiversity value by at least 10% against the existing onsite habitat baseline. An ecologist identifies habitats, measures their condition and calculates the baseline. They use the statutory biodiversity metric or, where eligibility rules allow, the Small Sites Metric.

The result is not simply a percentage of the land set aside for nature. Habitat area, distinctiveness, condition, strategic significance and the proposed habitat changes all matter. Area, hedgerow and watercourse units are accounted for separately. Where a smaller non-exempt scheme qualifies, our Small Sites Metric assessments explain the simplified calculation route.

A useful BNG design starts early. Retaining mature trees and habitats can reduce the units at risk, while well-placed habitat enhancement can support both landscape quality and wider nature recovery. Therefore, habitat assessment should inform a scheme before its layout becomes fixed.

For a fuller explanation of the assessment process, see ACP's BNG assessment and UKHab baseline survey and statutory biodiversity metric service.

The current statutory metric release is version 1.1.0, updated on 3 November 2026. Use the appropriate current tool and guidance for the application.

11 districts / two unitary cities / two National Parks

Which authority deals with BNG in Hampshire?

Hampshire is not a single local planning authority. Most ordinary development applications go to one of the district or borough councils, or to Southampton or Portsmouth City Council. Within the National Parks, their separate planning policies and decision-making arrangements apply. Hampshire County Council deals with minerals, waste and certain county development applications.

The table identifies the relevant geography. Always check the exact site address and planning boundary, particularly near National Park boundaries.

District and borough councils

Hampshire councils, National Parks and planning responsibilities
Planning areaUsually responsible for ordinary planning applicationsImportant distinction
Basingstoke and DeaneBasingstoke and Deane Borough CouncilAdopted Local Plan 2011–2029; higher BNG policy proposals remain emerging
East HampshireEast Hampshire District Council outside the National ParkWithin the South Downs, the National Park's planning policy applies
EastleighEastleigh Borough CouncilSouth Hampshire/Solent ecological constraints may also affect proposals
FarehamFareham Borough CouncilFareham Local Plan 2037 and the separate Welborne plan area need checking
GosportGosport Borough CouncilEmerging Local Plan 2042 is not an adopted replacement
HartHart District CouncilThames Basin Heaths SPA considerations can arise independently of BNG
HavantHavant Borough CouncilAdopted Core Strategy and Allocations Plan; replacement plan is emerging
New Forest districtNew Forest District Council outside the National ParkNational Park land is a different planning-policy area
RushmoorRushmoor Borough CouncilThames Basin Heaths SPA constraints can require separate mitigation
Test ValleyTest Valley Borough Council, subject to National Park boundariesNew Forest and Solent effects depend on the specific site
WinchesterWinchester City Council outside South Downs National ParkThe Local Plan 2020–2040 was adopted in March 2026; within the park, South Downs policy governs

City councils and National Parks

Hampshire councils, National Parks and planning responsibilities
Planning areaUsually responsible for ordinary planning applicationsImportant distinction
SouthamptonSouthampton City CouncilIts adopted plan framework remains in force; City Vision Local Plan is emerging
PortsmouthPortsmouth City CouncilPortsmouth Plan 2012 remains adopted while the new Local Plan is under examination
New Forest National ParkNew Forest National Park AuthorityAdopted National Park Local Plan 2016–2036 and its own local requirements
South Downs National Park (Hampshire portion)South Downs National Park Authority as planning authoritySome councils determine applications on its behalf; South Downs Local Plan policy SD9 applies

Check the boundary before choosing a plan

A district's name does not always tell you which plan applies. In parts of Winchester, East Hampshire and other districts, the South Downs National Park is the planning authority even if a district handles application administration under an agreement. Likewise, the New Forest National Park has its own adopted plan.

Use the Hampshire planning authority directory and the South Downs planning responsibility guide for boundary-sensitive cases.

Published December 2025 / mapped habitat priorities

Hampshire's Local Nature Recovery Strategy and habitat map

Hampshire's Local Nature Recovery Strategy (LNRS) was published on 8 December 2025. It covers the Hampshire strategy area, including Southampton, Portsmouth and the Hampshire portions of the New Forest and South Downs National Parks. The Isle of Wight has its own LNRS.

Its Local Habitat Map helps users find where nature is already important and where restoration may deliver wider benefits. It includes:

  • Areas of Particular Importance for Biodiversity (APIBs): established designated sites and mapped irreplaceable habitat.
  • Areas that Could Become of Particular Importance (ACBs): strategic opportunities for nature recovery.
  • Potential measures: mapped actions intended to achieve the strategy's biodiversity priorities.

For qualifying habitat measures, mapped strategic significance can influence the biodiversity metric. However, being inside an opportunity area does not automatically qualify every habitat proposal for an uplift. The proposed habitat, action and mapping must match the latest metric guidance.

The map is a starting point, not a substitute for a UKHab survey, habitat condition assessment, protected species evidence or a council's planning constraints check. Equally, an LNRS opportunity area is not by itself a new statutory nature conservation designation.

Local habitats that can affect your BNG design

Hampshire includes chalk grassland and chalk streams, heathland, ancient woodland, coastal wetlands, saltmarsh and urban green infrastructure. The particular survey and design considerations depend on what is present at the site, not on a county-wide assumption.

For example, habitat connectivity may be relevant around the South Downs; heathland and ancient woodland may be important around the New Forest; and coastal or intertidal habitats require particular care around the Solent. Urban projects in Southampton and Portsmouth may also present opportunities for habitat creation on smaller or fragmented sites.

Ecology surveys should identify the actual vegetation, habitats, constraints and feasible enhancement locations. Sensitive habitats and irreplaceable habitats require separate treatment: they cannot simply be treated as interchangeable units.

Read the published Hampshire LNRS and explore the Local Habitat Map.

Application date / red-line area / habitat impacts

Does your Hampshire project need statutory BNG?

The date of the planning application is important. For new applications made on or after 6 August 2026, qualifying development on a red-line site of 0.2 hectares or less is exempt if it does not adversely impact an onsite priority habitat.

Other exemptions can apply, including householder applications and the de minimis rule where the development does not affect onsite priority habitat and impacts less than 25 m² of onsite habitat and less than 5 metres of linear habitat. A new exemption also applies to certain wholly temporary developments permitted for no more than five years, subject to specific conditions.

The former general exemption for qualifying self-build and custom-build applications was removed for new applications from 6 August 2026. Saved earlier applications and some section 73 cases require separate transitional checks. Do not assume that a self-build project is exempt solely because it is self-build.

Six practical routes / evidence for your project

Hampshire BNG route-to-evidence checker

Use this guide to identify the evidence to check. Site and application details determine the correct outcome.

Six development situations and the evidence to check
Your situationFirst checkLikely next evidence
Householder extensionIs the application legally a householder application?BNG exemption statement where applicable; protected species and trees may still need assessment
New application on a site of 0.2 ha or less (from 6 August 2026)Red-line area, onsite priority habitat and application dateRecord the legal exemption basis and supporting plan; do not presume absence of ecological duties
Small non-exempt developmentExemption tests, habitat loss and Small Sites Metric eligibilityUKHab/baseline information, appropriate metric, mitigation and gain route
Major developmentExisting habitats, design alternatives and relevant local policiesCompetent ecological baseline, statutory metric, design options, long-term delivery strategy
Site within or near a designated areaProtected area, likely effect, National Park policies and species recordsEcological assessment, screening/Habitats Regulations evidence and mitigation as necessary, in addition to BNG
Site considering off-site unitsHabitat trading, metric geography, gain site registration and allocationOff-site unit evidence, legal security, allocation and Biodiversity Gain Plan

Important: A statutory BNG exemption is not an exemption from protected species law, the Habitats Regulations, planning policy or other ecological survey requirements.

For detailed exemption examples, use ACP's BNG exemptions guide.

Ask ACP to review your site brief →

Six planning steps / baseline through to delivery

What should you submit with a planning application?

1. Establish the site and planning authority

Confirm the red-line boundary, application type and date. Check whether the site is within a National Park, is affected by local designations or has a relevant neighbourhood plan.

2. Check whether statutory BNG applies

Record the exemption or transitional position with evidence. Where BNG applies, the national validation information generally includes the applicant's BNG statement, pre-development value, metric calculation, habitat plan and relevant information about degradation and irreplaceable habitats.

3. Survey and map the habitat baseline

Record UKHab habitat types, habitat condition, hedgerows and watercourses where relevant. Review suitable ecological records, designated sites and protected species constraints. For some schemes, additional field surveys may be needed.

4. Test the design and biodiversity metric

Consider avoidance first, then changes that retain or improve habitats. Test realistic habitat creation and enhancement proposals. Also verify distinct habitat trading rules; a headline 10% gain is not sufficient if the metric's individual requirements are not met.

5. Check locally required reports and mitigation

Each authority may have its own validation list and requirements for ecology reports, Habitats Regulations Assessment, tree information, nutrient mitigation, species surveys or supporting plans. These requirements are not identical across Hampshire.

6. Complete the Biodiversity Gain Plan before commencement

For an in-scope permission, the Biodiversity Gain Plan must normally be approved before development starts. Significant onsite gains and registered off-site gains generally require legally secured habitat management for at least 30 years. Start discussions about agreements, monitoring and responsibility early.

For related specialist work, see ACP's Biodiversity Gain Plan service and Habitat Management and Monitoring Plans.

Adopted plans / application evidence / national framework

Planning policy and validation: what changes across Hampshire?

Local planning decisions depend on the applicable development plan and the ecological evidence for the site. These six areas illustrate the different policy routes.

Winchester

The Winchester District Local Plan 2020–2040 was adopted on 24 March 2026. It replaces the former district plan documents. However, South Downs National Park policies apply to land within the Park.

South Downs National Park

The adopted 2019 South Downs Local Plan includes SD9, Biodiversity and Geodiversity. Use the Park’s planning policies and application requirements, including where a district council handles administration on its behalf.

New Forest National Park

The adopted 2019 plan includes SP5 for internationally important nature conservation sites and SP6, The Natural Environment. The Park’s local requirements, published on 1 September 2026, include a biodiversity checklist and relevant ecological surveys.

Southampton

The adopted Core Strategy framework includes CS22, Biodiversity. Southampton City Vision is an emerging Local Plan. Therefore, use the adopted framework and the city’s application checklist to scope the planning evidence.

Portsmouth

The adopted Portsmouth Plan 2012 includes PCS13, A Greener Portsmouth. The replacement Local Plan was submitted for examination on 18 March 2026. Check the city’s validation requirements, with the Biodiversity Gain Plan normally following permission and preceding commencement.

Basingstoke and Deane

The adopted 2016 Local Plan includes EM4, Biodiversity. A possible higher BNG target is under consideration through plan-making. It does not establish an adopted blanket 20% requirement.

Read local policy with the national framework

The current NPPF limits higher mandatory BNG targets to justified, deliverable, specific site allocations. Decision-makers should give no weight to other policies requiring gains beyond the statutory framework.

Read NPPF policies N1(2) and N2(3) with the application date, exemptions and relevant plan. Distinguish ecological information requests from requirements to deliver extra biodiversity units.

Eastleigh, Fareham, Gosport, Hart, Havant, Rushmoor, Test Valley, East Hampshire and New Forest District also have separate plans and local lists. Check the actual authority’s application guidance when scoping your submission.

Solent / New Forest / Thames Basin Heaths

Protected sites, nutrients and other constraints are separate from BNG

A 10% biodiversity calculation does not, by itself, demonstrate that protected sites or species are adequately safeguarded. Different legal tests may apply, including screening and appropriate assessment under the Habitats Regulations.

Around the Solent, nutrient neutrality and recreational disturbance can be material for certain development types and locations. Elsewhere, proposals may affect the New Forest designated habitats, the Thames Basin Heaths SPA, chalk streams, ancient woodland or protected species. The right assessment follows the impact pathway, not a generic county rule.

For example, a housing project may require both a BNG metric and a separate nutrient budget or strategic mitigation contribution. Do not assume that buying BNG units settles nutrient mitigation, SPA recreation impacts or protected species licensing. Some habitat measures may count towards more than one outcome only where the relevant current rules permit it and double counting is avoided.

Early ecological constraints work can reduce costly design changes and missed survey seasons.

On-site / registered off-site / long-term management

How can Hampshire developments deliver biodiversity gain?

The delivery approach should consider the specific application and the current statutory gain hierarchy.

For major development, the hierarchy gives preference to avoiding harm and suitable onsite habitat measures, then registered off-site gains where needed. Statutory credits are the last resort.

For non-major development applications made on or after 6 August 2026, if they are not exempt, onsite enhancement, onsite creation and registered off-site delivery sit at the same priority level under the revised hierarchy. Statutory credits remain the final option. Saved earlier applications and certain section 73 permissions follow transitional arrangements.

Off-site biodiversity units must match habitat trading requirements and the applicable metric calculations. The underlying gain site needs the right legal agreement, management commitments and registration. Its units must also be formally allocated to the development. A proposed or advertised habitat bank is not proof that units are registered, available, suitable or allocated.

A Hampshire location may help with local delivery priorities, but location alone does not guarantee a favourable spatial risk score. Check the metric's relevant geographic tests, particularly for watercourse units and projects spanning catchments.

Read our guide to off-site biodiversity units and search England’s biodiversity gain sites register.

Ten checks / coordinated planning evidence

Hampshire BNG planning checklist

  • I have identified the correct local planning authority and confirmed National Park boundaries.
  • I know the application type, date and accurate red-line site area.
  • I have checked current statutory exemptions and any transitional rules.
  • I have reviewed designated sites, priority habitats, species and existing habitat records.
  • I have checked the Hampshire LNRS map and considered suitable habitat priorities.
  • I have a proportionate, defensible UKHab baseline and condition assessment where needed.
  • I have selected the correct current metric and met habitat trading rules.
  • I have considered avoidance, onsite options and any compliant off-site route.
  • I have checked local validation requirements and separate nutrient/Habitats Regulations duties.
  • I know who will prepare the Biodiversity Gain Plan and secure 30-year management where required.

Ask ACP about your BNG assessment. Share your planning location, proposed works and development stage.

Scope / survey / practical delivery

How ACP can support your Hampshire project

We can help identify the likely BNG pathway, arrange or assess appropriate habitat surveys, calculate biodiversity units and coordinate evidence with project designers and planning advisers. Where ecological constraints, National Park requirements or off-site delivery affect the proposal, we can outline the additional information needed before assumptions become commitments.

Our advice starts with the actual site and development proposal. We use that information to define the survey, calculation and delivery scope.

You may also find our BNG process guide and BNG consultants service useful.

For the wider regional picture, explore biodiversity net gain in South East England.

Practical answers / application planning

Hampshire biodiversity net gain FAQs

Is biodiversity net gain mandatory for every development in Hampshire?

No. The statutory framework generally requires at least 10% BNG for qualifying development in England, but exemptions and transitional arrangements apply. Check the application date, site size, habitat impacts and development type.

Is a development site of 0.2 hectares or less now exempt?

For planning applications made on or after 6 August 2026, the new exemption can apply where the red-line site is no larger than 0.2 hectares and the proposal does not impact an onsite priority habitat. Earlier or section 73 applications may be treated differently.

Does a self-build home automatically qualify for an exemption?

No. The former self-build/custom-build exemption was removed for new applications from 6 August 2026. An application may qualify under a different exemption, but it must meet that exemption's conditions.

Which council should receive my BNG documents?

Usually the district, borough or city council for the land. However, sites in the New Forest or South Downs National Parks can fall under a different local planning authority. Check the planning boundary before submitting.

Does Hampshire have one local nature recovery map?

The Hampshire LNRS covers its own strategy area, including Portsmouth, Southampton and the Hampshire portions of the National Parks. The Isle of Wight has a separate LNRS, and sites outside Hampshire follow the relevant neighbouring strategy.

Does the LNRS map automatically change a site's biodiversity units?

No. Mapped potential measures can affect strategic significance where the metric criteria are satisfied, but an ecologist must establish whether the habitat type, proposed action and location qualify.

What is the difference between a BNG assessment and a Biodiversity Gain Plan?

A BNG assessment establishes the habitat baseline and tests how the proposal can meet the objective. For an in-scope permission, a Biodiversity Gain Plan is the formal document submitted for approval before development starts.

Can a Hampshire developer purchase biodiversity units off-site?

Yes, where the scheme and metric requirements allow. The units must be appropriate, legally secured, registered and allocated. An advertised offer is not evidence of completed allocation.

Can a small non-exempt project go straight to off-site BNG?

For qualifying non-major applications made on or after 6 August 2026, the revised gain hierarchy places registered off-site options alongside onsite creation and enhancement. Statutory credits are still the last resort.

Does achieving 10% BNG remove the need for nutrient mitigation?

No. Separate requirements can arise from effects on protected sites, including nutrients and recreational pressure around parts of the Solent. Their legal tests are distinct from the BNG calculation.

How long must biodiversity habitats be maintained?

Significant onsite enhancements and registered off-site gains normally need securing and management for at least 30 years. The appropriate legal mechanism, monitoring and responsible party should be considered early.

What should I send ACP for a Hampshire BNG quotation?

Send the site location or plan, planning authority if known, development description, drawings, application stage and any existing ecology or habitat information. This helps identify a proportionate scope and the likely 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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Hampshire BNG

Sources and references

Reviewed 7 November 2026.