Who signs a viability assessment and on what basis

A viability assessment is signed by the practitioner who prepared it, and in practice that is a chartered surveyor or valuer working to the RICS professional statement on financial viability in planning. Who signs a viability assessment matters less than the basis on which they sign it, because that professional statement imposes an objectivity duty: the author owes a duty to produce an objective assessment even though one party is paying for it. Authorities know this, their reviewers quote it, and an assessment written as advocacy is the quickest route to a rejected submission.

The professional standard that governs the work

The RICS professional statement on financial viability in planning sets conduct and reporting requirements for members carrying out this work. It is mandatory for RICS members and it has become the de facto standard that authorities expect, whoever the author is.

Its central requirement is objectivity. The practitioner must act with independence and impartiality, must not allow the instructing party's commercial objective to determine the conclusion, and must report the assessment as an objective appraisal rather than as a negotiating position.

Two practical duties follow. The author must disclose conflicts and decline instructions where objectivity cannot be maintained. And the report must be capable of being understood and tested by a third party, which means showing inputs, sources, assumptions and sensitivities rather than presenting a residual land value and a conclusion.

National practice guidance on viability reinforces the second point. It expects assessments to be presented in a standardised and accessible format, with an executive summary, and to be made publicly available so that the evidence can be scrutinised.

Objectivity duties and the conflict of interest rules

The conflict rules bite harder here than in most planning disciplines, because the same firms act for developers and for authorities.

Acting for a developer on one site while reviewing for the authority on a neighbouring site is the obvious case. Less obvious is the firm that provided the acquisition advice on the land and then prepares the viability case arguing that the price paid cannot support policy compliance. The appraisal then has to explain why the firm's own earlier advice is not the benchmark.

Disclosure is the mechanism, not a cure. An author who discloses a connection and still reaches a conclusion favouring the instructing party will have that conclusion discounted, which is why the better firms refuse the instruction. The general principles are the same ones set out in conflicts of interest for a technical report author.

Where the matter is heading to an inquiry the duties tighten again, because the author becomes an expert witness with duties to the tribunal that override the client's interest, as expert evidence at a planning inquiry sets out.

Inputs the author must justify

Every line in a residual appraisal is contestable and three lines carry most of the argument.

The price paid for the land is the point that recurs. National guidance is clear that the price paid is not a justification for failing to comply with policy, because the policy requirements were known when the land was bought. An assessment built on the purchase price will be rejected on that ground alone, and the author who signs it has not applied the professional statement.

Abnormal costs deserve the same scrutiny. Remediation, piling, diversions and highway works are real and they need evidence from the discipline that priced them, not an allowance inserted into the appraisal.

The council's reviewer and their role

Authorities appoint an independent reviewer, usually a specialist consultancy, and routinely recover the cost from the applicant. The reviewer's job is to test the inputs and report to the authority, not to negotiate on its behalf.

Expect the review to arrive as a line-by-line commentary: accepted inputs, contested inputs, and a recalculated residual with the reviewer's own assumptions. The gap between the two appraisals is usually concentrated in benchmark land value and sales values rather than spread across everything.

Treat the reviewer as a professional counterpart rather than an opponent. A short meeting to agree which inputs remain in dispute will narrow a thirty-page disagreement to three numbers, and three numbers can be resolved.

A Viability Assessment is a report type where councils expect a suitably qualified author and where professional review is strongly advised. An AI-assisted draft can structure the narrative, set out the policy framework and list the evidence required, and the appraisal itself and the signature on it belong to the qualified practitioner.

Transparency and publication expectations

National guidance expects viability assessments to be published, with a limited exception for demonstrably commercially sensitive material, and expects an executive summary written so that a non-specialist can follow it.

Plan for publication from the start. An appraisal drafted on the assumption of confidentiality will contain material the author would not want in the public domain, and redacting it later produces a document nobody can follow.

Where such information does exist, such as a confidential contract sum, provide the figure to the authority and the reviewer and publish the analysis without it, with the redaction explained. A wholesale confidentiality claim invites the response that the assessment cannot be relied on.

Where an assessment is rejected

Rejections cluster around five issues.

1. Benchmark land value derived from the purchase price rather than from existing use value plus a premium.
2. Sales values unsupported by comparable evidence, or evidence from a different market period.
3. Abnormal costs asserted without a technical source.
4. No sensitivity analysis, so the authority cannot see how far the conclusion depends on contested inputs.
5. A report written as advocacy, with conclusions that do not follow from the figures.

The fifth is the hardest to fix, because the remedy is a different author. The first four are fixable in a second iteration if the underlying evidence exists.

Briefing to avoid a stalemate

Three moves prevent most deadlocks.

Agree the appraisal model and the input schedule with the authority before the assessment is written. A spreadsheet both sides can run, with an agreed structure, removes a month of argument about methodology.

Instruct the author on the professional statement basis explicitly, in writing, and accept that the answer may not suit you. An appraisal that concludes the scheme can support a higher contribution than you hoped is still the right appraisal to submit, and a negotiating position dressed as an assessment will cost more in time than it saves.

And offer a review mechanism. Where the gap is about future values rather than current ones, a late-stage review clause in the obligation resolves it by deferring the question, and authorities accept them readily. Set the position out in the Affordable Housing Statement so the two documents tell the same story, and if you need a reviewer to look over a draft, the professional directory is the route.

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. For specialist technical reports, qualified professional input may be required.