Reading a viability assessment as a community objector
A viability assessment is an argument, not an accounting exercise. National guidance puts the burden on the applicant, and every assumption in the document can be tested.
A viability assessment is an argument that the scheme cannot afford the affordable housing the local plan requires. It is not an accounting exercise and it is not neutral. It is a set of assumptions chosen by the applicant, each of which can be tested, and the national guidance starts from the position that the applicant has to justify departing from policy rather than the council having to prove the policy is affordable.
So the first thing to know as an objector is that you are allowed to read it. National guidance says viability assessments should be publicly available, and the authority should be able to explain any redaction. If the document is not on the planning portal, ask for it in writing and ask on what basis any part is withheld.
Why viability is used to reduce policy contributions
The policy framework intends viability to be settled at plan-making stage. When a local plan sets an affordable housing requirement, it should have been tested for deliverability across the plan area, and the expectation is that schemes complying with the plan's policies are viable.
The consequence is that at application stage the burden sits with the applicant. Where up-to-date policies set out the contributions expected, the national guidance is clear that it is up to the applicant to demonstrate why a particular site cannot deliver them, by reference to circumstances specific to that site.
That matters for the tone of an objection. "The scheme should provide the policy level of affordable housing" is a correct statement of the starting point, not a wish. The right question is whether the applicant has demonstrated a site-specific reason, and whether the figures supporting it survive examination.
Two site-specific reasons do carry genuine weight: abnormal costs that are evidenced rather than estimated, such as demolition of a difficult structure, remediation of contamination with an intrusive investigation behind it, or infrastructure demonstrably required by the authority. And a planning history that has changed the policy position since the land was bought.
What does not carry weight is the price the applicant paid for the land. More on that below.
The structure of a viability assessment
Every assessment, whatever its length, reduces to the same comparison.
| Component | What it contains | Where the argument sits |
|---|---|---|
| Gross development value | Sales or rental values multiplied by floor areas, plus any commercial element | Values per square metre, and whether comparables are local and current |
| Development costs | Build cost, abnormals, professional fees, contingency, finance, marketing and sales costs | Build cost source, abnormal evidence, fee percentages |
| Developer return | Profit expressed as a percentage of value or cost | Whether the percentage is justified for the risk profile |
| Residual land value | Value minus costs minus profit | Arithmetic only |
| Benchmark land value | What the land is worth in its existing use plus a premium | The most contested figure in the document |
The conclusion is reached by comparing the residual land value with the benchmark land value. If the residual exceeds the benchmark, the scheme can afford the policy contributions. If it falls short, the applicant argues for a reduction.
That means there are only two ways to produce a deficit: push costs and profit up, or push the benchmark land value up. Almost every argument you will want to make is an argument about one of those.
Benchmark land value and where the argument sits
The benchmark is based on existing use value plus a premium to the landowner, and the national guidance is explicit that the price actually paid for the land is not the benchmark. A developer who overpaid cannot pass the overpayment to the community by reducing affordable housing.
Three tests to apply.
What is the existing use value, and is it evidenced? For a redundant office building, the existing use value is the value of that building in its current lawful use and condition, which on a vacant and obsolete building can be modest. Assessments sometimes substitute an alternative use value based on a hypothetical consent that does not exist, which is only legitimate where that alternative use would be permitted and is actually available to the applicant.
What premium has been applied, and on what basis? The guidance envisages a premium that provides a reasonable incentive for a landowner to bring the site forward, taking account of policy requirements, and it should reflect the plan's own viability evidence rather than a market expectation formed before the plan was adopted.
Does the benchmark reflect policy compliance? This is the circularity trap. A benchmark derived from transactions where purchasers assumed reduced affordable housing bakes the policy failure into the land value. Point it out where you see it.
Build costs, sales values and profit assumptions
These are the lines a non-specialist can interrogate most easily, because each has a public reference point.
Build costs should be sourced to a recognised cost index, stated per square metre, with the index date given and the location factor applied. Ask whether the figure is a median or an upper quartile, whether externals and abnormals have been counted twice, and whether the contingency sits on top of a cost figure that already includes risk.
Sales values should be evidenced by comparables that are local, recent, and for comparable unit types. A scheme of two-bedroom flats evidenced by sales of four-bedroom houses two miles away is not evidence. Ask whether the values are current or forecast, because an assessment using today's costs against today's values but no growth in either is making a choice.
Professional fees are commonly taken at a percentage of build cost. Marketing and sales costs are a percentage of value. Finance is a rate over a period, and the period assumed should match the programme the applicant has submitted elsewhere in the application.
Developer return is the figure people fixate on, and the national guidance gives indicative ranges: in the region of 15 to 20 per cent of gross development value for market housing, with a lower figure for the affordable housing element reflecting its lower risk, where a figure of around 6 per cent of value is indicated. A return above the range needs justifying by reference to the actual risk of the scheme, and a scheme on a clean site with a willing registered provider purchaser for the affordable units is not high risk.
Transparency and the presumption of disclosure
The national guidance on viability states that assessments should be prepared on the basis that they will be made publicly available, other than in exceptional circumstances, and that even then the key inputs should be published.
In practice, the common forms of partial disclosure are a redacted appraisal with the inputs removed, a summary without the model, or a statement that the assessment is commercially confidential. None of those is the default position, and the authority can be asked to explain which exception it is relying on.
Where disclosure is refused, two routes exist. A request under freedom of information or environmental information legislation, with the public interest test applied to any claimed commercial exemption. And a representation to the committee that the assessment cannot be given weight if members and the public cannot see it.
Ask also whether the authority has commissioned its own independent review, who paid for it, and whether that review is published. Authorities commonly recover the cost of the review from the applicant, which is appropriate, and the review itself is usually the most useful document in the file for an objector, because it is written by a surveyor who has already asked the questions you would ask.
Review mechanisms and late stage reviews
Where an authority accepts a reduced contribution, the mitigation is a review mechanism, and this is the most achievable outcome for an objector to push for.
An early stage review triggers if implementation has not begun within a stated period, typically two years, and retests viability on current figures. A mid-term review retests at a defined point in the build programme. A late stage review retests after a stated proportion of units have been sold, capturing actual sales values rather than forecasts, with any surplus applied to additional affordable housing or a commuted payment.
Four points to press on a review mechanism:
- that there is one at all, and that it is in the section 106 agreement rather than described in a committee report
- that the late stage review captures actual sales receipts, not a re-run of the original forecast
- that there is a cap on how much the applicant retains from any surplus, and a floor below which no clawback occurs, both stated as figures
- that the review is not a one-way ratchet in the applicant's favour, allowing contributions to fall but not rise
A permission granted with a reduced offer and a properly drafted late stage review is a materially different outcome from one granted with a reduced offer and no review.
Questions to put to the council's assessor
Keep the representation short and put the questions in a numbered list, because that is the form an officer can take to the applicant.
- What is the existing use value, how is it evidenced, and is any alternative use value based on a consent that exists?
- What premium has been applied to existing use value, and how does it relate to the plan's viability evidence?
- Is the build cost from a recognised index, at what date, with what location factor, and does the contingency double-count risk?
- Are the sales comparables local, recent and for comparable unit types, and are values current or forecast?
- What developer return has been assumed for market and for affordable units, and how does it sit against the indicative ranges in national guidance?
- Has the authority commissioned an independent review, and will it be published?
- If a reduced contribution is accepted, what review mechanism is proposed, and is it in the agreement?
Send it within the consultation period, copy the ward councillor, and ask whether the application will be determined at committee. Where the scheme has been through developer consultation, the Statement of Community Involvement in the application file records what the applicant says it was told. The report index explains the other documents, and related reading includes independent review of a viability appraisal, benchmark land value where the site already has consent and how to check what a section 106 agreement delivered.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Am I entitled to see a viability assessment?
National guidance says assessments should be prepared on the basis that they will be publicly available, other than in exceptional circumstances, and that key inputs should be published even then. If it is not on the planning portal, request it in writing and ask which exception any redaction relies on. Information access legislation is the fallback route.
Does the price paid for the land set the benchmark?
No. The guidance is explicit that the price paid is not the benchmark land value. The benchmark is existing use value plus a premium reflecting a reasonable incentive for the landowner, informed by the plan's own viability evidence. A developer who overpaid cannot pass that overpayment on by reducing affordable housing.
What developer profit is considered reasonable?
National guidance gives indicative ranges in the region of 15 to 20 per cent of gross development value for market housing, with a lower figure for the affordable element reflecting its reduced risk, around 6 per cent of value. A return above the range needs justifying against the actual risk profile of that specific scheme.
What is a late stage review mechanism?
A clause in the section 106 agreement that retests viability after a stated proportion of units have been sold, using actual sales receipts rather than forecasts, with any surplus applied to additional affordable housing or a commuted payment. Press for it to be in the agreement, to capture real receipts, and to have a stated cap and floor.
Which single document is most useful to an objector?
The authority's own independent review of the applicant's assessment, where one has been commissioned. It is written by a surveyor who has already interrogated the inputs, and it usually identifies the contested figures directly. Ask whether a review exists, who paid for it, and whether it will be published.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.