What a planning inquiry actually costs to run
Sitting days drive every other line in an inquiry budget. How advocacy, witnesses, case management and event costs behave, and the issues to close before committing.
Planning inquiry cost is driven by one variable above all others: the number of sitting days. Everything else scales off it. Counsel is engaged for the hearing plus preparation, each expert witness bills for proofs, rebuttals and attendance, the planning consultant runs the case throughout, and the venue and transcription run per day. Add a day and you add a day of everyone.
That is why the first budgeting question is not what will this cost, but how many days will this sit, and how many issues am I prepared to fight.
The Planning Inspectorate does not charge the appellant a fee for a section 78 appeal. The costs below are your own professional team and the practical costs of running the event.
The cost structure
An inquiry budget breaks into four blocks that behave differently.
Advocacy. Counsel's fee usually comes as a brief fee covering preparation and the first day or days, plus a refresher per subsequent day. A junior barrister on a householder-scale issue sits at the bottom of the range, and leading counsel on a strategic housing or Green Belt case sits far above it. The brief fee is the larger part on a short inquiry and the refreshers dominate on a long one.
Expert evidence. Each discipline in dispute needs a witness who can be cross-examined: planning, highways, landscape, heritage, ecology, noise, viability. The cost per witness covers the proof of evidence, the summary, rebuttal evidence, statement of common ground input, conference with counsel and attendance for their session. Attendance is not one day: a witness is usually there for the day before and the day after their own evidence.
Case management. Somebody runs the appeal: the statement of case, the core documents bundle, the statement of common ground, the draft conditions, the timetable compliance, liaison with the case officer. On a large inquiry that is most of a planner's time for several months.
Event costs. Venue hire where the authority does not provide one, audio-visual and streaming, the transcript if one is commissioned, document printing, travel and accommodation for the team, and the site visit arrangements.
How length drives the total
| Inquiry length | Typical shape | Cost behaviour |
|---|---|---|
| 2 to 3 days | One or two issues, two or three witnesses | Brief fee dominates, lowest total |
| 4 to 6 days | Three or four issues, a full planning team | Refreshers and witness attendance become the largest block |
| 8 to 10 days | Housing supply or heritage plus several technical topics | Roughly double a four-day case rather than proportionate, because the team grows too |
| Over 10 days | Strategic schemes, recovered appeals, multiple parties | Budget as a project with its own contingency |
The non-linearity catches people out. Going from four days to eight days does not double the cost, it more than doubles it, because the longer inquiry usually means more issues, which means more witnesses, each of whom brings proofs, rebuttals and attendance.
The lever you control is the number of disputed issues. Every issue you can close by agreement before the inquiry removes a witness, a proof, a rebuttal and often half a day of cross-examination. A statement of common ground that really narrows the dispute is the most cost-effective document in the whole process, and the one most often left to the last fortnight.
Costs of the other side you might be asked to pay
Separate from your own budget is the possibility of an award of costs against you. In planning appeals, costs are awarded on the basis of unreasonable behaviour that has caused another party to incur wasted expense. The Planning Inspectorate's published guidance sets out the categories.
Behaviour that has attracted awards against appellants includes pursuing an appeal with no reasonable prospect of success on the material before the inspector, failing to produce evidence to substantiate a ground of appeal, withdrawing an appeal late without good reason after the authority has prepared, and persisting with an appeal after a change in circumstances removes its basis.
Awards against authorities arise where a refusal is unsupported by any evidence, where a reason for refusal is vague or relies on policy that does not say what the authority claims, or where the authority fails to attend or to defend its own reasons. Pulling apart the reasons for refusal early is therefore both a tactical and a financial exercise, as our note on committee refusals against officer advice explains.
Two realities about costs applications. They are the exception, and the threshold of unreasonableness is meaningful rather than nominal. And a partial award, covering the costs attributable to one unreasonable aspect rather than the whole inquiry, is a common outcome.
Budgeting for a conditional outcome
Even a successful inquiry has a tail. Conditions get argued at the inquiry and then discharged afterwards, each discharge needing the technical document behind it. A section 106 agreement often has to be completed before the decision issues, which means legal costs running in parallel with the inquiry itself and a unilateral undertaking drafted in case the authority will not sign.
Build three lines into the budget beyond the hearing:
- Legal costs of the planning obligation or unilateral undertaking, including the authority's costs.
- Post-decision technical work to discharge pre-commencement conditions.
- A contingency for an adjournment, which happens, usually because a party needs time to respond to new evidence.
On the last of those, an adjournment part way through is the expensive failure mode. It means a second mobilisation of the whole team, and the usual cause is late evidence. Serving proofs on time, and refusing to serve new material late yourself, protects the budget as well as the case.
Where written representations save money
Most appeals do not need an inquiry, and choosing the procedure is the single biggest cost decision in the process. The Inspectorate determines the procedure, but the appellant's view in the appeal form carries weight.
Written representations suit appeals where the issues are narrow, the evidence is documentary, and nobody needs to be cross-examined. The cost is the statement of case and supporting documents, with no advocacy and no attendance. For a householder appeal, where a short-deadline written procedure applies, this is the only sensible route.
A hearing sits between the two: an inspector-led discussion with no formal cross-examination, no advocates in the usual sense, and a shorter programme. It suits cases turning on planning judgement rather than on contested technical evidence.
An inquiry earns its cost where the case turns on facts that have to be tested by cross-examination. Housing land supply is the classic example, because deliverability claims collapse or survive under questioning in a way that written exchange never achieves. Earlier decisions on the same authority's supply are worth gathering first, as our note on using appeal decisions in a planning application sets out. Heritage harm, highway safety and viability are the other three where cross-examination does real work. Our note on highway safety refusals and visibility splay evidence shows the kind of technical dispute that benefits.
Where the choice is finely balanced, run the arithmetic. If an inquiry would cost several times a written representations appeal and the prospects are similar, the inquiry has to be buying something: a better chance on a contested factual issue, or a decision with reasoning solid enough to deter a challenge.
What to settle before committing
Three questions I would want answered before authorising an inquiry budget.
Which issues will be in dispute at the inquiry, as opposed to in the refusal notice? Authorities routinely drop reasons once evidence is served, so ask the officer directly which reasons they intend to defend and with which witness.
Who is giving evidence on each disputed issue, and is their proof going to withstand cross-examination? An expert who has not been cross-examined before, on a proof written by somebody else, is a risk to the whole case.
And what is the alternative? A revised application addressing the reasons for refusal sometimes delivers a permission faster and for a fraction of the inquiry cost, particularly where the refusal was design-led. The appeal is not always the cheaper route to a consent, and a fresh application preserves the appeal option.
A well-organised Planning Statement and a clean evidence base prepared at application stage reduce inquiry cost more than any negotiation with counsel, because the proofs are then written from documents that already exist.
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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.
Frequently asked questions
Does the Planning Inspectorate charge a fee for an appeal?
No. There is no appeal fee for a section 78 appeal against refusal. The costs of an inquiry are your own professional team, the practical costs of running the event, and any award of costs made against you for unreasonable behaviour. Budget the team, not a fee.
What makes one inquiry cost more than another?
The number of sitting days, which follows from the number of disputed issues. Each issue needs a witness who can be cross-examined, and each witness brings a proof, a rebuttal, conference time and several days of attendance. Closing an issue by agreement removes all of that at once.
When are costs awarded against an appellant?
Where behaviour has been unreasonable and has caused another party wasted expense. Published examples include pursuing an appeal with no reasonable prospect of success on the material before the inspector, failing to substantiate a ground of appeal, and withdrawing late without good reason after the authority has prepared its case.
Is a hearing cheaper than an inquiry?
Usually, yes. A hearing is an inspector-led discussion without formal cross-examination or advocates in the usual sense, and the programme is shorter. It suits cases that turn on planning judgement rather than contested technical evidence. Written representations are cheaper again where the evidence is documentary and nobody needs questioning.
When is an inquiry worth the money?
Where the case turns on facts that have to be tested by cross-examination. Housing land supply is the clearest example, because claims about site deliverability either survive questioning or collapse. Heritage harm, highway safety and viability are the other issues where cross-examination does real work.
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.