Planning authorities assess whether potential sites are suitable, available and achievable before relying on them for housing, employment or other development. These tests help distinguish land that merely exists on a map from land that has a realistic prospect of being developed within an identified period.
Suitability considers the planning and physical appropriateness of the location and proposed use. Availability examines ownership, control and whether the land can genuinely come forward. Achievability considers viability, market demand, infrastructure, abnormal costs and whether delivery is realistically possible.
Sustainability is important, but the formal three-part terminology is suitable, available and achievable. Sustainable location, transport and access to services are normally considered within suitability and the wider site-selection process rather than replacing that first test.
Value My Land can undertake a free initial review of the site against the three tests and identify the evidence most likely to improve its assessment. A postcode, map pin, what3words reference or site plan is usually enough to begin.
Send us the location and council assessment for a free initial review.
The land availability framework
A Local Plan must be based on land that can realistically support the authority’s strategy. Suitable, available and achievable are connected tests used to assess whether sites can contribute to development needs and within what timeframe.
The tests are commonly applied through a HELAA, SHLAA, site selection methodology, brownfield land review or other land availability assessment. The authority records the evidence available at the time and uses it to compare sites, estimate capacity and distinguish deliverable or developable opportunities from land that should not be relied upon.
A site may have been submitted through a Call for Sites but still fail because its location is unsuitable, the owner has not confirmed availability or the costs make development unachievable. Conversely, an initially constrained site may improve where access is secured, policy changes, infrastructure is funded or better evidence demonstrates a workable capacity.
The tests do not grant permission and are not a substitute for the Local Plan selection decision. A site can satisfy all three and still not be allocated if it does not fit the spatial strategy or if other options perform better. The assessment identifies credible supply; the authority must then decide which land to plan for.
The tests should be applied to the proposed use and period. Land may be suitable for employment but not housing, available in ten years but not five, or achievable only at a lower capacity. A binary yes or no can conceal important qualifications that affect planning strategy and value.
For landowners, the published reasoning is often more useful than the final category. Our HELAA and SHLAA guide explains how these conclusions sit within the wider evidence base.
The correct formal tests are suitable, available and achievable. Sustainability is an important planning consideration that normally forms part of suitability and the authority’s wider comparison of locations.
Test one: suitability
Suitability asks whether the location and proposed development are acceptable in planning terms or could become acceptable through policy change and proportionate mitigation.
The authority considers adopted and emerging policy, settlement hierarchy, countryside or Green Belt designations, allocations and the intended spatial strategy. A current policy conflict can be recorded while recognising longer-term potential.
Access to services, jobs, education, public transport, walking and cycling affects whether the location supports sustainable development. See the location assessment guide.
The site needs a credible means of access and movement strategy. Frontage alone does not prove that visibility, width, junction capacity, sustainable transport or third-party control can be resolved.
Flood risk, ecology, landscape, agricultural land, contamination, ground conditions, trees and heritage can reduce capacity or make a proposed use unacceptable. The assessment should distinguish manageable constraints from fundamental harm.
Noise, odour, air quality, industrial hazards, privacy, daylight and compatibility with surrounding uses can affect whether housing, employment or another use is appropriate.
Suitability relates to the amount and form of development that can be accommodated. A site may be suitable at 100 homes but not the 180 assumed in a submission once infrastructure and mitigation are allowed for.
Free three-tests review
Send us the site location and any council assessment. We can review the suitability, availability and achievability conclusions, identify whether information is missing or outdated and consider what evidence may justify a revised position.
Test two: availability
Availability requires a genuine prospect that the land can be brought forward for the proposed use. It concerns ownership, intention, legal control and the period in which development could occur.
The owner should confirm that the land is available for the proposed development and provide an authorised contact. Silence, an old submission or speculative identification by the council may not establish current availability.
All land needed for the development, access, drainage and infrastructure should be identified. Multiple titles, ransom strips or separate ownerships can affect whether the whole opportunity is available.
Agricultural, business or residential occupation can affect timing and vacant possession. Lease terms, statutory rights, notices and relocation should be understood rather than assumed to end when permission is granted.
Options, promotion agreements, overage, pre-emption rights, charges and exclusivity arrangements may control decisions or sale. The council needs confidence that these interests support rather than prevent delivery.
Access, utility routes, drainage outfalls or mitigation may depend on land outside the ownership. Availability should address whether rights exist or can realistically be secured within the required period.
Land may be available now, after a tenancy ends, following assembly with neighbours or only in a later plan period. The assessment should record a realistic window instead of forcing an immediate yes or no.
Test three: achievability
Achievability asks whether there is a reasonable prospect that development will occur at a particular point. It combines market, cost, infrastructure, viability and delivery considerations.
There should be demand for the proposed homes, employment space or other use. The type, tenure, scale and phasing may need to reflect the local market rather than an assumed maximum capacity.
Build costs, abnormal ground works, remediation, access, utilities, drainage, biodiversity, planning obligations and finance affect whether the scheme can support policy requirements and a viable land value.
A site can be suitable but unachievable until a road, school, sewer, electricity connection or strategic project is funded and programmed. Dependencies should be identified with realistic lead-in times.
Complex environmental assessment, land assembly, compulsory acquisition, uncertain access or unresolved policy can reduce the prospect of delivery within the stated period even where a solution may exist eventually.
Evidence of credible market interest can support achievability, but a speculative approach or unsigned heads of terms is not conclusive. The party’s resources, strategy and commitment matter.
The authority should consider application lead-in, infrastructure, conditions, reserved matters, sales rates and phasing. Larger sites may be developable over the plan period without being deliverable in the first five years.
Timing within the land supply
The three tests inform when a site can contribute to supply. The planning framework distinguishes sites expected to deliver in the near term from those capable of development over a longer period.
A deliverable housing site should be available now, offer a suitable location now and be achievable with a realistic prospect of delivery within five years. Additional evidence may be needed depending on the site’s planning status and scale.
Allocation or permission does not automatically prove five-year delivery. Infrastructure, conditions, ownership, reserved matters, developer commitment and lead-in times can prevent a site contributing when the authority expects.
For landowners, a claim of early delivery should be supported by a programme and the steps required to reach commencement rather than a general willingness to sell.
A developable site should be in a suitable location and have a reasonable prospect of being available and viably developed at the point envisaged. It may require longer-term policy, infrastructure or land assembly work.
Strategic sites commonly fall into later periods because of their scale and dependencies. A realistic trajectory can strengthen the plan more than an optimistic early date that cannot be sustained at examination.
A site can move between periods as evidence changes. Updated ownership, infrastructure funding, planning progress or market conditions may bring delivery forward, while unresolved constraints can delay it.
Methodology and judgement
Assessment methodologies vary, but the authority should apply a consistent, proportionate and transparent process that records evidence, assumptions and reasons for its conclusions.
Some assessments use red, amber and green categories, while others use narrative findings or numerical scores. A score is a decision aid rather than a substitute for planning judgement. The underlying evidence and the weight given to each issue should be understood.
A constraint may operate as a knockout, a capacity reduction or a matter requiring mitigation. Flood risk affecting the entire site is different from a surface-water corridor that can be incorporated into open space. The published assessment should avoid treating those scenarios as equivalent.
Authorities may assess broad locations before detailed boundaries are known. This can be appropriate for strategic planning, but a landowner promoting a specific parcel should ensure that the site’s own access, ownership and constraints are not obscured by a wider area conclusion.
The three tests should be revisited as information changes. Planning permission, an expired option, a new owner, infrastructure funding, revised flood mapping or a new Local Plan strategy can materially alter the outcome. Landowners should not assume that an old HELAA entry remains accurate indefinitely.
Comparison also matters. A site can be suitable, available and achievable in isolation but perform less well than alternatives because it is less sustainable, requires greater infrastructure or creates more environmental harm. The Local Plan allocation decision considers those broader choices.
The next policy stage is explained in our Local Plan allocation guide. It is there that the authority decides which assessed sites best meet needs and align with the chosen strategy.
A landowner should challenge an assessment only where there is a clear evidential, methodological or planning reason. Disagreeing with a score is not enough without showing why the conclusion should change.
Target the decisive issue
We can review whether the weakness arises from policy, location, ownership, access, infrastructure, viability or missing information. This helps focus the next submission or representation on the issue capable of changing the council’s conclusion.
Improving the evidence base
The most useful evidence answers the council’s stated concern and is proportionate to the plan stage.
Supply an accurate site plan, title information, owner authority and details of every parcel needed for access, drainage or infrastructure.
State the intended use, realistic capacity, delivery period and whether the proposal depends on adjoining land or a wider strategic scheme.
Show the relationship with settlements, services, transport, employment and the emerging spatial strategy, including any policy change required.
Provide targeted access, flood, drainage, ecology, landscape, heritage, contamination or utilities evidence where those issues influence suitability or capacity.
Confirm landowner intention, tenancies, agreements, third-party rights and when vacant possession or control can realistically be achieved.
Identify infrastructure, abnormal costs, policy contributions, promoter or developer involvement and a credible programme from plan-making to commencement.
Free initial assessment
Our free initial assessment identifies the site’s apparent strengths, weaknesses and the next evidence stage.
We consider policy, settlement fit, access, surrounding uses, environmental constraints, infrastructure and realistic capacity.
We consider ownership, occupation, agreements, third-party land, access control and the period in which the site could come forward.
We consider market, abnormal costs, infrastructure dependencies, planning risk, delivery programme and whether further professional work appears proportionate.
Diagnosing the assessment properly
The first step is to identify which test has failed and whether the conclusion is caused by incorrect information, missing evidence, timing or a more fundamental planning problem.
Availability can often be clarified through owner confirmation, title information, tenancy dates, access agreements or coordination with neighbouring owners. The response should state when the land can actually come forward rather than simply asserting immediate availability.
Suitability may improve through a revised boundary, lower capacity, alternative access, environmental buffer or different use. Targeted technical evidence is useful where it demonstrates that a constraint can be managed and shows the land needed for the solution.
Achievability can change when infrastructure funding is secured, abnormal costs are quantified, a promoter is appointed or market evidence improves. A later delivery period may be more credible than disputing the current five-year conclusion.
Some findings reflect the authority’s chosen growth strategy rather than missing site evidence. A remote location, strong Green Belt function or reliance on major unplanned infrastructure may require long-term policy change and cannot be solved by another short technical note.
Severe flood risk, irreplaceable habitat, incompatible neighbouring uses or an access solution outside realistic control may make the proposed use unsuitable. The landowner should consider an alternative development concept or other land use before continuing to spend.
A focused representation can challenge inconsistent methodology or factual error, but it should not overstate the site. Where the council’s conclusion is well supported, monitoring and preserving future flexibility may be the most commercially responsible strategy.
Site-specific outcomes
A site can pass or fail the tests in different combinations. These examples show why the final conclusion should record qualifications and timing.
The policy position may make the site suitable, but it is not available where the owner does not intend to develop or sell. The authority should not rely on it until availability changes.
An old allocation does not override current ownership evidence.
The owner may be willing to release the land immediately, but the location can remain unsuitable because residents would depend on private cars and the site does not support the settlement strategy.
Availability cannot cure an unsustainable location.
Redevelopment may be supported in principle and the owner may be willing, but contamination, demolition and infrastructure can make the scheme unachievable at the assumed use or density.
Alternative uses, public funding or a revised capacity may change the conclusion.
The location may be suitable and controlled by a promoter, but delivery is not achievable until a bypass, school or utility reinforcement is programmed.
The site may be developable in a later period without being deliverable now.
Each parcel may appear suitable, but the whole site is unavailable where owners have not coordinated the access and infrastructure land.
A collaboration or equalisation arrangement can improve confidence and prevent one owner holding up delivery.
Flooding, ecology or landscape may prevent development across the whole submission but leave a contained area that is suitable and achievable.
A revised red line and lower capacity can convert a negative assessment into a credible opportunity.
Testing the published reasoning
A conclusion can only be understood properly by reading the site entry alongside the methodology, thresholds, evidence date and definitions used by the authority.
Check the assessment purpose. A HELAA designed to identify broad land supply may use high-level desktop evidence, while a Local Plan site selection process may apply more detailed sustainability, infrastructure and environmental criteria. The same site can receive different treatment because the questions are different.
Review the minimum site size and capacity assumptions. A small parcel may be excluded from one assessment but remain relevant as a windfall, brownfield or neighbourhood plan opportunity. Exclusion by threshold does not necessarily mean the land is unsuitable for planning permission.
Identify whether criteria operate as absolute exclusions or weighted considerations. A statutory designation may prevent reliance on one part of a site, while distance from a service may receive an amber score that is balanced with other factors. The response should use the methodology actually adopted.
Check the evidence date. Ownership, planning status, flood mapping, infrastructure, public transport and policy can change. A conclusion based on information several years old may justify an update, but the landowner should provide evidence of the change rather than merely state that the assessment is outdated.
Compare similar sites. Inconsistent scoring can be relevant where two locations have materially comparable characteristics, but the comparison must account for boundary, capacity, access, constraints and delivery. Selecting only the favourable parts of another assessment is unlikely to be persuasive.
Finally, distinguish assessment from selection. Passing the three tests does not require the authority to allocate every site. A representation seeking allocation must also explain why the location supports the spatial strategy and performs appropriately against reasonable alternatives.
The aim is not to replace the council’s planning judgement with the landowner’s preference. It is to ensure that the judgement uses correct information, a consistent method and a realistic understanding of delivery.
Control of the complete development proposition
A site may appear physically suitable but fail the availability or achievability tests if the land needed for a complete scheme cannot be controlled or delivered on workable terms.
Availability should be tested across the whole proposed site, not only the principal title. A development may require land for access, visibility splays, drainage, utilities, landscape mitigation, biodiversity provision or an education contribution. If any essential parcel is outside the promoter’s control, the assessment should identify how it will be secured and whether the owner is willing.
Multiple ownership is not automatically a reason to reject a site. However, the authority may reasonably seek evidence that the parties can act together. A collaboration agreement, equalisation arrangement, common promoter or agreed masterplan can reduce the risk that one owner delays infrastructure or seeks a disproportionate share of value.
Agricultural, commercial or residential tenancies can affect both timing and vacant possession. The length of the term, break provisions, security of tenure, compensation and relocation needs should be understood. A general statement that a tenant can be removed should not be made without legal advice and a realistic programme.
Options, promotion agreements and conditional contracts can demonstrate commitment, but the agreement itself does not make the site achievable. The party controlling the land must have the incentive, funding and obligations needed to pursue planning and coordinate the technical team. Longstop dates and termination rights should be consistent with the plan-making timetable.
Achievability also depends on how value and costs are shared. Where the first parcel must fund a strategic access, school, drainage system or utility reinforcement serving later land, an unresolved equalisation issue can delay the whole scheme. The assessment should explain the broad mechanism even if detailed figures will follow.
Access rights and restrictive covenants should be distinguished from ownership. The land may be available for sale but incapable of development without an easement, covenant release or third-party consent. Early title review can identify whether the right exists, whether it is wide enough for the proposed use and whether alternative routes are realistic.
The evidence supplied to the council should be proportionate and avoid unnecessary disclosure of commercially sensitive terms. A signed owner confirmation, plan of controlled land and clear explanation of outstanding rights may be sufficient at an early stage. More detailed evidence may be needed where the authority has identified a specific delivery concern.
Availability is not fixed permanently. Ownership, agreements, tenancies and intentions can change during a long Local Plan process. Landowners should therefore confirm their position when assessments are updated and avoid allowing an expired agreement or outdated contact to become the reason the site is discounted.
Where several owners are involved, see our guide to multiple landowners and development land for coordination, equalisation and decision-making issues.
August 2026 National Policy
The final framework distinguishes the new plan-making system from legacy plans still progressing under transitional arrangements. The correct policy tests therefore depend on the legal route and stage of the particular plan rather than the consultation label alone.
Policies PM8 and PM9 require proportionate evidence and a structured land assessment. Site promotion should explain suitability, availability, achievability, infrastructure and delivery without commissioning application-level work that is unnecessary at the plan stage.
The site-assessment record should identify consistent criteria, explain how constraints and opportunities were scored, and show why selected sites form an appropriate strategy. A representation is stronger where it traces a specific defect in the evidence or comparison rather than relying on preference alone.
New-system local plans are assessed under PM15 as Positive, Appropriate, Effective, Consistent with national policy and in Conformity with any spatial development strategy. A legacy plan may continue under the policy and legal regime preserved by Annex A, so the examination basis must be stated expressly.
Plans prepared under the 2026 regulations and spatial development strategies use the August 2026 framework. Other plans may continue under the December 2024 NPPF and its transition rules. Neighbourhood plans submitted by 17 August 2026 also receive specific protection.
A landowner submission should identify the applicable plan system, policy version, evidence defect, consequence and precise remedy. References to the December 2024 NPPF should be retained only where they accurately describe a legacy or transitional plan.
Read the National Planning Policy Framework published on 17 August 2026.
Continue your site-assessment research
These guides explain the submission, evidence and technical subjects surrounding the three tests without duplicating this page’s focus on suitability, availability and achievability.
Understand how councils assess potential land supply.
Read guideLearn how sites are identified and submitted for assessment.
Read guideFollow the later selection, consultation and adoption decision.
Read guideReview the broader development-potential assessment for landowners.
Read guideAssess settlement fit, services, transport and surrounding uses.
Read guideUnderstand access control, visibility, junctions and movement.
Read guideReview capacity, connection, reinforcement and delivery dependencies.
Read guideCoordinate ownership, decisions, costs and land assembly.
Read guideSee how adopted and emerging policy affects suitability.
Read guideNo. The established three-part terminology is suitable, available and achievable. Sustainability remains important and is normally considered within suitability and the wider spatial strategy.
No. It means the site may represent a credible development option. The authority must still compare alternatives, choose a spatial strategy and select allocations that meet its needs and plan vision.
Yes. A location may be appropriate for development while the owner is unwilling to release it, a tenancy prevents delivery, required access land is uncontrolled or an existing agreement conflicts with the proposed route.
Yes. The owner may support development, but abnormal costs, infrastructure, weak demand, policy contributions or planning risk may mean there is no reasonable prospect of viable delivery within the relevant period.
Yes. Policy, infrastructure, ownership, access, market conditions and evidence can change. The assessment should record timing and be updated rather than treating every current constraint as permanent.
Suitability is the broader test covering planning policy, location, environmental constraints, access, amenity and the appropriateness of the proposed use. Sustainability is a central consideration within that assessment but is not identical to it.
It can support the case, but the authority should still consider the developer’s commitment, viability, infrastructure, planning risk and delivery programme. An informal approach or speculative offer does not prove that development will occur.
The council needs confidence that all required land can come forward. Separate owners may need a collaboration, equalisation or landowners’ agreement, coordinated promotion and clear decision-making before the whole site is treated as available.
Yes. Reducing the developable area may protect constraints, lower infrastructure requirements and improve design or viability. A realistic capacity is more useful than a higher figure that cannot obtain permission or be delivered.
Send a site plan or location, approximate area, ownership position, proposed use and any council assessment. Access, planning, technical or developer information is helpful but not essential at the initial stage.
Send us the location of the land and any HELAA, SHLAA or site assessment extract. We will undertake a free initial review of suitability, availability, achievability and the evidence likely to influence the council’s conclusion.
You do not need a complete technical file before contacting us. Early review can identify the decisive weakness, prevent unnecessary surveys and help define a more credible capacity, timescale or promotion strategy.
Request Your Free Site ReviewSend us the land location and any published assessment. We can review the site against the suitable, available and achievable tests and identify the next proportionate step.
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