What an independent viability review costs and who pays

The applicant pays for the independent viability review. That is the short answer, and it surprises developers the first time it happens, because the reviewer is instructed by the local planning authority, reports to the authority, and may well conclude that the scheme can afford more affordable housing than the appraisal claimed. There is no statutory fee for the exercise. The authority asks for an undertaking to meet the reviewer's costs before it commissions the work, and it will not progress the application until that undertaking is in place.

The cost of an independent viability review depends entirely on the complexity of the appraisal and the number of rounds. A clean single-phase residential appraisal with evidenced inputs is a different job from a phased mixed-use scheme with three land value benchmarks and a disputed existing use.

Why an authority commissions an independent review

National viability guidance places the burden on the applicant to demonstrate that particular circumstances justify departing from what the plan requires. An authority receiving that case has to test it, and most planning departments hold no in-house valuation capability.

So they buy it in, usually from the District Valuer Services within the Valuation Office Agency, or from a private practice on a framework. Both are common. The choice matters less than the terms of the instruction.

Officers commission a review when the applicant argues that policy-compliant affordable housing or the full package of contributions cannot be delivered. They also commission one where a review mechanism in a section 106 agreement falls due, and on some authorities as a matter of course on any major application seeking a reduction.

Who instructs and who pays

The authority instructs. The reviewer's duty is to the authority, and the applicant is not the client even though the applicant pays.

That distinction has practical consequences. You do not direct the scope. You will not see a draft. Correspondence usually goes through the case officer rather than directly, although most reviewers will hold a technical meeting with the applicant's appraiser, and asking for one early is sensible.

Payment is normally secured in one of three ways: a written undertaking to meet reasonable fees, a payment on account before the instruction, or a clause inside a planning performance agreement covering the review alongside the wider programme. The planning performance agreement route is the most workable, because it fixes the scope and the timetable as well as the fee.

Ask for a fee estimate and the scope of the instruction before you sign the undertaking. Authorities rarely refuse, and an open-ended undertaking on a complex scheme is an uncontrolled cost in the budget. Treat it the way you would treat any other outlay before work starts, alongside the items in the article on utility connection costs in a development budget.

What the reviewer is given and what they ask for

The reviewer gets the submitted viability assessment, the application drawings and schedules, the officer's summary of the policy position, and whatever the applicant has supplied as evidence.

Then come the questions. In practice they cluster in the same places every time:

• The benchmark land value and how it was derived, including the existing use value and the premium applied
• Evidence for the land price actually paid, and why it is or is not relevant
• The build cost source, and whether it is a measured cost plan or an all-in rate
• Abnormals, itemised, with evidence rather than a percentage allowance
• Sales values and rents, with comparable evidence and dates
• The developer return assumed, and its basis
• Finance assumptions, the appraisal period and the phasing
• Professional fees, marketing and contingency as percentages of what

National guidance indicates that a return in the range of 15 to 20 per cent of gross development value may be a suitable return to developers, while noting this will vary with circumstances. Reviewers use that range as a starting point and push back on anything above it without justification.

The single most common request is for the live appraisal file rather than a printed output. Withholding it prolongs the review and costs you money, because the reviewer then rebuilds the model.

Time added to the determination programme

A review does not fit inside a 13 week determination period alongside everything else, and it is the most frequent reason for an agreed extension of time.

The sequence is instruction, fee undertaking, document transfer, first review, applicant response, and often a second iteration. Each handover involves the case officer, who has other applications. Where the appraisal is incomplete, the clock effectively stops until the missing evidence arrives.

Two things shorten it. Commission your own appraisal early enough that the submitted version is final rather than provisional, and agree the inputs that are capable of agreement before submission, so the review concentrates on the genuine points of difference. A pre-application discussion that settles the benchmark land value methodology, even without settling the figure, removes the largest single source of delay.

Programme the review as a named item with a duration, in the same way you would programme a seasonal survey. Anything that is only a line in a covering letter tends to be forgotten until it becomes critical.

When a revised appraisal triggers a second review

Submit a revised appraisal and you will normally pay for a second review. Authorities take the view, reasonably, that a new appraisal is new work.

The way to avoid paying twice is to treat the first review as the last one. That means responding to the reviewer's points with evidence rather than with a re-run of the model at different assumptions. A revised appraisal that changes six inputs at once invites a full re-review; a response that supplies the cost plan and the comparable evidence the reviewer asked for, leaving the model alone, often does not.

Where the difference comes down to one input, propose a narrow instruction: ask the authority to seek the reviewer's opinion on the benchmark land value alone. Reviewers will quote for that, and it is a fraction of a full review.

If the disagreement survives all of this, it becomes an appeal point, and costs exposure changes character. The article on appeal costs awards and how they are assessed is relevant before anyone commits to arguing viability at inquiry.

Publication and confidentiality

Assume the assessment will be published. National guidance expects viability assessments to be made publicly available save in rare circumstances, and where information is withheld an executive summary should still be published.

The review itself is normally published too, as a background paper to the officer report or to a committee report. Councillors read it, and objectors read it more carefully than councillors do.

So write the appraisal knowing it will be read by people who are not valuers and who are looking for the weak assumption. Two habits help: state every input with its source in a schedule, and explain in plain words why the land value benchmark is what it is. Redaction requests should be narrow, specific and justified by genuine commercial sensitivity, because a broad request reads as concealment and gets refused.

Submitting an appraisal that reviews quickly

The cost of the review is largely determined by what you submit. A Viability Assessment that reviews quickly has the following in it from the start:

1. A stated methodology, naming the professional standards followed and the appraisal model used.
2. An inputs schedule, every figure with a source and a date.
3. A measured cost plan from a quantity surveyor, not an all-in rate per square metre.
4. Abnormals itemised against the site investigation and survey evidence.
5. Comparable sales or rental evidence, with the comparables identified.
6. The benchmark land value derivation set out step by step, including the existing use and the premium.
7. Sensitivity analysis on the two or three inputs that actually move the result.
8. The live appraisal file, offered in the covering letter.

Where a reduction in affordable housing is sought, address the tenure question as well as the quantum in the Affordable Housing Statement, because a change of mix is frequently more achievable than a change of number.

For anyone costing the document side of a major application, the pricing page sets out what PlanScope charges per report or on the Professional plan. Viability work needs a qualified professional author, and an AI-assisted draft is a structure for that professional to work into rather than the appraisal itself.

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.