Viability at plan making or at application stage

National guidance puts viability testing at the plan making stage. Councils set their policy requirements, test them across the plan area, and then applications that comply with up to date policies are assumed to be viable. An assessment submitted with an individual application is the exception, and the burden of showing that the exception applies sits with the applicant.

That reversal of onus is the whole difference between the two exercises. At plan making you are one voice in a process testing typologies. At application stage you are asking a council to accept that its policy cannot be met on your site.

Two exercises with different questions

Plan-wide testing works on standardised inputs and broad typologies, which is why it rarely predicts any individual site accurately. That is not a flaw. It is the level of resolution the exercise needs, and it also means an applicant cannot rely on the plan-wide work having covered their circumstances.

When an application stage assessment is accepted

Guidance expects the applicant to demonstrate that particular circumstances justify one. The arguments that succeed tend to fall into three groups.

Circumstances that have changed since the plan was adopted, such as a material shift in market conditions or in construction costs, evidenced rather than asserted. Site specific factors the plan-wide testing did not capture, typically abnormal costs, unusual constraints or a form of development not represented in the typologies. And situations where the site was not allocated or tested at all.

What does not work: the price paid for the land. National guidance is explicit that the price paid is not in itself a justification for failing to meet policy, because paying too much is a commercial decision rather than a planning consideration.

Benchmark land value is where most disputes sit

Benchmark land value is existing use value plus a premium to the landowner, informed by market evidence and by the policy requirements of the plan. The premium has to be enough to provide a reasonable incentive to release the land, and no more.

The circularity is obvious once you see it. If benchmark land value were set by market transactions alone, and those transactions were struck on hope value ignoring policy, then policy would never be deliverable. Guidance closes the loop by requiring the benchmark to reflect policy requirements, which is explained further in benchmark land value: existing use value plus a premium.

At plan making the benchmark is set for typologies. At application stage it is set for your site, and it is the input a reviewer will test hardest.

Transparency and publication

Viability assessments submitted with applications are expected to be made publicly available other than in exceptional circumstances, and even then an executive summary should be published. Write on that basis from the first draft.

In practice councils publish more than applicants expect and redact less than applicants hope, a pattern set out in council viability evidence: what officers publish and redact. Commercially sensitive material such as a contractor's tender build-up can sometimes be handled by appendix, but the inputs driving the conclusion will be visible.

Review mechanisms

Where viability is uncertain, or where a scheme will be built over several years, the council will usually want a review mechanism in the section 106 agreement rather than simply accepting the appraisal.

The common structures:

1. An early stage review, triggered if development has not been substantially implemented within a set period, re-testing viability on current costs and values.
2. A mid stage review at a defined point in the programme, often tied to a percentage of units completed.
3. A late stage review before final unit sales, capturing uplift in sales values above those assumed.
4. A cap on the additional contribution, usually at the policy compliant level, so the developer is never worse off than full compliance.

Negotiate the trigger dates and the cap carefully. A review clause with an unrealistic implementation trigger converts a viability concession into a deferred obligation the scheme cannot carry.

An illustrative example

Illustrative only: a brownfield site not allocated in the plan, with a policy requirement of 35 per cent affordable housing. The applicant submits an assessment showing 18 per cent is the most the scheme supports, driven by remediation and a piled solution.

The council's reviewer accepts the abnormals in part, adjusts the benchmark land value downwards because the comparables used were cleaner sites, and concludes 24 per cent is supportable. Permission is granted at 24 per cent with an early stage review if implementation slips beyond 18 months and a late stage review capped at the policy compliant figure.

Both sides moved. Neither got the number they opened with, which is what a properly evidenced negotiation looks like.

Where the two exercises collide

An applicant who argues that the plan-wide testing was wrong is fighting the plan rather than the application, and that argument belongs at examination. Once a plan is adopted, the viability of its policies has been found sound, and a reviewer will say so.

The productive argument is narrower: this site differs from the typologies tested, in these respects, for these evidenced reasons. Frame it that way and the conversation stays about your scheme. Frame it as a critique of the plan and you invite the council to defend its evidence base instead of looking at yours.

Who reviews it and what carries weight

Councils instruct District Valuer Services or an independent consultant, and commonly recover the cost from the applicant. The reviewer works to the same guidance and to the RICS professional statement on conduct and reporting in viability, which sets expectations on objectivity and conflicts of interest. Who is qualified to sign this work is covered in RICS registered valuers and viability assessments in planning.

Evidence that carries weight, consistently:

• Transacted comparables for values, with dates, rather than asking prices.
• A quantity surveyor's elemental cost plan, not a rate per square metre.
• Ground investigation reports supporting any remediation or foundation abnormal.
• Absorption evidence from comparable local schemes where sales rate is in issue.
• A cash flow, so timing and finance cost can be tested rather than assumed.

Councils expect a suitably qualified author, and professional review before submission is strongly advised. Where the obligation ends up below policy, the Affordable Housing Statement has to carry the same numbers and explain the review mechanism in terms a member can follow.

Start the Viability Assessment early enough that the reviewer sees it before the officer report is drafted. Late evidence gets discounted for a simple reason. By then there is no time left to test it.

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.