Reopening a viability appraisal at appeal

Viability refusals reach inquiry because two experts have put different numbers into the same model and reached opposite conclusions about whether a scheme can carry the policy compliant affordable housing. The inspector has to decide which set of inputs is right, and the input that decides most cases is benchmark land value.

National guidance starts from the assumption that the policy requirements in an up to date plan are viable, and puts the burden on the applicant to show that particular circumstances justify departing from them. That framing matters at appeal, because it means an appellant arguing viability is arguing against a presumption rather than starting level.

Why these appeals end up at inquiry

Written representations rarely work for a contested appraisal. The dispute turns on professional judgement about a handful of inputs, and the value of testing those judgements through cross-examination is exactly what an inquiry provides.

The pattern is familiar. The authority refuses for failure to provide policy compliant affordable housing. The appellant says the scheme cannot carry it. Both sides instruct valuers. The gap between the two appraisals is often concentrated in two or three lines, and the rest of the model agrees to within a few per cent.

Identify those lines early and say so. An appeal that presents two complete appraisals and leaves the inspector to find the differences wastes everybody's time and usually damages the appellant, because the party bearing the burden is the party who needed to be clear.

Benchmark land value and the existing use value debate

Benchmark land value is established from the existing use value of the land plus a premium to the landowner. The premium has to provide a reasonable incentive for a willing landowner to bring the site forward while reflecting policy requirements, and it should be informed by market evidence rather than asserted.

The recurring disputes.

Whether existing use value has been correctly assessed, particularly where a site has a marginal existing use such as low grade industrial or storage, and where the authority argues the use is effectively obsolete.

Whether an alternative use value should be used instead, which is only appropriate where that alternative has permission or is a real and deliverable alternative rather than a theoretical one.

The size of the premium, expressed either as a percentage uplift or by reference to comparable transactions, and whether the comparables reflect schemes that themselves met policy.

And the price actually paid for the site, which is not a justification for failing to comply with policy. An appellant who paid a price assuming no affordable housing is in a weak position, and inspectors say so directly.

The inputs an authority will challenge

Expect the authority's valuer to go through the appraisal line by line. The productive approach is to anticipate each challenge in the proof rather than respond to it in rebuttal.

Abnormals attract the most scrutiny, because they are site specific and hard for the other side to test. Evidence them with a costed schedule tied to the ground investigation and the design, not with a lump sum in a table.

Where the scheme also carries nutrient mitigation, biodiversity units or a substantial infrastructure package, price those explicitly rather than folding them into a general allowance. An inspector can only give weight to a cost that has been shown.

Transparency and what gets published

Guidance expects viability assessments at application stage to be made publicly available, other than in exceptional circumstances, and to be presented in an accessible format with an executive summary.

Plan for that. Redaction requests are sometimes granted for commercially sensitive material, and they are not a way to keep the whole appraisal out of the public domain. Write the assessment knowing that objectors and the local press may read it.

The professional standards for viability work also matter. The recognised professional statement for financial viability in planning requires objectivity, independence and reporting that is not conditional on the outcome. An appraisal prepared by someone with a fee dependent on the result is vulnerable in cross-examination, and so is one where the same firm advised on the land purchase.

Review mechanisms as the compromise

Most viability appeals that succeed do so with a review mechanism attached, and offering one early is often the difference between a dismissal and a grant.

An early stage review triggers if development has not begun within a set period, testing whether conditions have improved. A late stage review tests actual values and costs at or near completion and captures a share of any surplus for additional affordable housing or a payment in lieu. Mid stage reviews are used on longer phased schemes.

The drafting points that matter are the trigger dates, the treatment of costs already incurred, the profit level at which surplus is shared, the cap on additional contributions, and whether the additional provision is delivered as units or as a payment. Put the drafted mechanism in the appeal documents as an offer rather than describing it in principle.

An inspector considering a scheme that offers a transparent review mechanism is being asked to accept a lower provision now with a defined route to more later. That is a much easier decision than accepting a permanently reduced provision on the strength of a contested appraisal.

Evidence from comparable transactions

Comparables carry weight when they are close in date, location, scale and planning status, and very little when they are not.

Present them in a table with the date, the address, the site area, the consented scheme, the affordable provision assumed and the price, and explain each adjustment. Anonymised comparables are weaker, and an inspector is entitled to discount a transaction that cannot be checked.

Be ready for the argument that a comparable reflects a scheme with below policy affordable housing, which makes it circular evidence for a benchmark that assumes the same. That point is made in most viability inquiries and an appellant needs an answer to it.

Presenting an appraisal the inspector can follow

Four things make the difference.

1. A single agreed appraisal model, with both parties' inputs run through the same file, so that the output difference is attributable line by line.
2. A one-page schedule of agreed and disputed inputs, with the effect of each disputed input on the residual value stated in pounds.
3. A sensitivity analysis showing how the conclusion moves across a realistic range on the two or three inputs that matter.
4. A plain English summary of what the appellant says the scheme can afford and why.

Agreeing the model is the single most useful step, and it belongs in the statement of common ground. The same discipline applies to the proofs themselves, as our note on proofs of evidence and rebuttals sets out.

Keep the affordable housing position consistent between the appraisal, the Affordable Housing Statement and the draft section 106. Inconsistency between those three is picked up within the first hour of an inquiry.

Before committing, read the refusal reason carefully, because a refusal that cites both viability and a design or heritage objection is a different case from one that cites viability alone. Our note on reading reasons for refusal covers how to sort them.

A Viability Assessment is a report type where councils expect a suitably qualified author working to the recognised professional standard, and professional review is strongly advised. This is general guidance, not legal advice. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.

Browse all 66 PlanScope report types to assemble the evidence base behind a viability case.