Who prepares a viability assessment and who reviews it
A planning viability assessment is an opinion with an audit trail, not a case. Who should write it, which inputs a council reviewer checks first, and how to keep the process short.
A planning viability assessment should be prepared by someone competent in development appraisal and valuation, and in practice that means a chartered surveyor working to the Royal Institution of Chartered Surveyors professional statement on financial viability in planning. The question of who can prepare viability assessment planning submissions is not answered by a licence, because there is no reserved title for it. It is answered by the standard the author is bound to, and by whether the council's own reviewer can follow the arithmetic.
The reviewer is the audience. Write for them.
The professional statement and what it requires
The Royal Institution of Chartered Surveyors issued a professional statement on financial viability in planning that is mandatory for its members. The core of it is objectivity: the author acts with independence of judgement, states their instructions, declares any conflict, and does not advocate for the client's position in the way a negotiator would.
That changes the document. A viability assessment prepared to the statement reads as an opinion with reasoning and an audit trail, not as a case. It discloses the instructions received, names the author and their relevant experience, and states where judgement has been applied rather than evidence.
Members are also expected to avoid conditional fee arrangements that would compromise objectivity. Ask about fee basis when you appoint, because a council reviewer who discovers a success-related fee will discount the whole report.
For practical purposes the author of a Viability Assessment should be a chartered surveyor or a development appraiser working to an equivalent standard, with the valuation element signed by someone competent to value. Where a planning consultant assembles the policy case and a surveyor does the appraisal, make clear in the report who did what.
Valuation competence against appraisal skill
These are related and not identical, and the difference shows up in the inputs.
Valuation competence produces the gross development value, the benchmark land value and the existing use value. These are valuations, and they need comparable evidence, an understanding of the local market and a method stated against professional valuation standards.
Appraisal skill produces the cash flow: the build cost profile, the finance assumptions, the sales rate, the phasing and the sensitivity testing. This is modelling, and the errors here are arithmetic and logic rather than judgement.
A report weak on the first gets challenged on evidence. A report weak on the second gets challenged on mechanics, which is worse, because a model that does not reconcile undermines every number in it.
Ask for both in the appointment. And ask who will attend an appeal if one follows, because the person who signed the appraisal is the person who will be cross-examined on it.
The inputs a council will interrogate first
Reviewers go to the same places in the same order.
| Input | What the reviewer checks | Common weakness |
|---|---|---|
| Benchmark land value | Whether existing use value plus a premium has been used, and the evidence for the premium | Reliance on the price actually paid |
| Gross development value | Comparable evidence, date, adjustments and the sales assumptions | Comparables from a different submarket |
| Build cost | The cost base, the date, the source and the externals allowance | An all-in rate with no breakdown |
| Developer return | The percentage, the basis it is applied to, and the justification | A figure asserted without reference to risk |
| Abnormals | Whether they are evidenced by survey rather than allowed as a percentage | Contingency and abnormals double counted |
The benchmark land value is where most assessments are won or lost. National guidance is explicit that the price paid for land is not in itself a justification for failing to meet policy requirements, and the expected approach is existing use value plus an appropriate premium to the landowner, informed by market evidence.
On developer return, the Planning Practice Guidance indicates that a return in the region of 15 to 20 per cent of gross development value may be considered a suitable return to developers for a typical scheme, while recognising that an alternative figure may be appropriate in particular circumstances. Quote that range accurately and justify any departure from it with reference to the risk profile of the specific scheme, not to a house standard.
The council's reviewer and how to work with them
Most authorities commission an independent review rather than assessing viability in-house, and the cost is commonly recovered from the applicant. The reviewer is usually a surveyor with the same professional obligations as the author.
Three things make the process shorter. Send a working appraisal model rather than a locked summary, because a reviewer who can see the formulas spends their time on assumptions instead of reverse-engineering totals. Provide the evidence pack with the report, including the comparables schedule and the cost plan, rather than on request. And answer the first round of questions in full even where you disagree, setting out the disagreement separately.
Where the reviewer reaches a different conclusion, the gap is almost always in two or three inputs. Ask them to identify which, and negotiate on those rather than re-running the whole exercise. The case for paying for an independent view of your own position before submission is set out in when an independent peer review is worth paying for.
Transparency, publication and confidentiality
National guidance expects viability assessments to be publicly available, with any commercially sensitive material limited to what is necessary and justified. In practice that means assuming the report will be published and read by objectors.
Write it accordingly. Keep narrowly sensitive material, such as a specific tenant's covenant terms, in a short confidential annex with a reasoned request for it to be withheld, rather than asking for the whole appraisal to be kept private. A blanket confidentiality request tends to be refused and tends to colour how the rest is read.
The affordable housing position that emerges should be carried into the Affordable Housing Statement so the two documents tell the same story, including the tenure split and the delivery mechanism.
Review mechanisms and who monitors them
Where viability supports a reduced policy contribution, authorities commonly secure a review mechanism in the section 106 agreement: an early-stage review if the scheme has not started within a set period, a late-stage review once sales are substantially complete, or both.
Someone has to run those reviews, and the agreement should say who, on what inputs, within what timescale, and with what dispute resolution. Nominating the original author is usual and raises the same objectivity point as at submission.
Briefing an assessment that will be scrutinised
Give the author the facts rather than the answer. Provide the title and any overage, the survey information including ground conditions and services, the cost plan, the sales strategy, and the policy requirements as the council states them. Then ask for an opinion.
Ask for the sensitivity analysis up front: what happens to the conclusion if values move, if build costs move, or if the benchmark land value is set at the council's figure rather than yours. Knowing the point at which the scheme becomes policy compliant is more useful in a negotiation than a single bottom line.
Where you need an AI-assisted first draft reviewed and signed by a qualified author, the professional directory is the route to a reviewer, and the habit of reading a background properly is covered in reading a consultant CV for real competence.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A viability assessment is a report type where councils usually expect a suitably qualified author, and professional review is strongly advised. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Is there a licence to prepare viability assessments?
No reserved title exists. Competence comes from the standard the author is bound to, which in practice is the Royal Institution of Chartered Surveyors professional statement on financial viability in planning, mandatory for its members. It requires objectivity, disclosure of instructions, declared conflicts and a stated basis for every judgement applied.
What developer return does national guidance indicate?
The Planning Practice Guidance indicates that a return in the region of 15 to 20 per cent of gross development value may be considered suitable for a typical scheme, while accepting that a different figure can be appropriate in particular circumstances. Justify any departure by reference to the risk profile of that specific scheme.
Can the price paid for the land justify a reduced contribution?
No. National guidance is explicit that the price paid is not in itself a justification for failing to meet policy requirements. The expected approach to benchmark land value is existing use value plus an appropriate premium to the landowner, informed by market evidence, which is where most assessments are challenged.
Will my viability assessment be published?
Assume so. National guidance expects assessments to be publicly available, with commercially sensitive material limited to what is necessary and justified. Put narrowly sensitive items in a short annex with a reasoned request to withhold them, rather than asking for the whole appraisal to be kept confidential.
Who pays for the council's independent review?
Commonly the applicant, under an agreement with the authority. The reviewer is usually a surveyor bound by the same professional obligations as the author. Sending a working appraisal model with visible formulas, plus the comparables schedule and cost plan, shortens the process considerably.
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.