The cost of putting retrospective development right

Retrospective planning cost is rarely just the application fee. The fee itself is the same as it would have been in advance, but the concessions that soften a normal application do not apply, the levy consequences can be severe, and if an enforcement notice has already been served the arithmetic changes again. A porch built two courses too tall can be regularised for a few hundred pounds. A barn converted without consent, with the levy exemption lost, can run into five figures before anyone has drawn anything.

Work out which of the four routes you are on before spending anything.

The fee for a retrospective application

Section 73A of the Town and Country Planning Act 1990 allows an application for planning permission for development already carried out. The fee is calculated on the same national scale as an ordinary application, so a householder extension costs the householder rate and a new dwelling costs the dwelling rate.

Fees are set by national regulations and subject to annual indexation, so take the figure from the current published schedule rather than from an older article or a fee calculator you saved.

The application is determined on its planning merits, not on the fact that the work was done first. That the building exists is not a material consideration in its favour, and in practice most officers assess it exactly as they would a proposal on paper.

Why there is no free resubmission

A normal application carries a useful concession. Where an application is refused or withdrawn, a further application of the same character on the same site can usually be made without a further fee within a stated period, once.

That concession does not extend to retrospective applications. Get it refused, amend the scheme, and you pay again. Where the first application is finely balanced, this is a strong argument for taking pre-application advice or for lodging the application with the amendments already made rather than trying the optimistic version first. Verify the current position in the fee regulations, because the concession has been amended more than once.

What an enforcement notice costs to fight

If an enforcement notice has been served under section 172, the position hardens considerably. An appeal is made to the Planning Inspectorate on the statutory grounds, and where you appeal on the ground that permission ought to be granted, a deemed planning application arises with its own fee, historically set at a multiple of the ordinary application fee.

Add professional fees on top. An enforcement appeal run on written representations with a planning consultant and a measured survey is a substantial commitment, and a hearing or inquiry more so. Costs awards are available in appeals but follow unreasonable behaviour rather than the outcome, so winning does not mean recovering your expenditure.

Compliance works and their expense

Where the appeal fails or none is made, the notice has to be complied with. Demolition of a completed structure costs more than not building it, because the work is careful rather than wholesale, waste has to be removed, and the remaining building needs making good.

Non-compliance is a criminal offence, and prosecution in the magistrates' court brings a fine with no upper limit for the most serious cases, together with the council's costs. Authorities can also carry out the works in default and recover the expense as a charge on the land.

Proving lawfulness, and what the evidence costs

Where the breach is old enough, immunity may have accrued and a lawful development certificate under section 191 is the way to establish it. The time limits were changed by the Levelling-up and Regeneration Act 2023, which moved enforcement time limits in England to ten years across the board for breaches that began after the change took effect in 2024. Older breaches may still fall under the previous four-year rule, so the date the breach began determines which applies. Check the current position for your circumstances.

The cost here is evidential rather than procedural. Expect to pay for a measured survey, statutory declarations from people who can speak to the period, collation of dated invoices, utility bills, photographs and delivery records, and often a planning consultant to assemble the bundle. The fee for the certificate is modest by comparison. Councils decide these applications on evidence alone, so thin evidence produces a refusal even where the use was lawful all along.

The levy, surcharges and lost exemptions

This is the expense people do not see coming. Community Infrastructure Levy exemptions and reliefs, including the self-build exemption and the residential extension exemption, generally have to be claimed and acknowledged before any work starts on site.

Build first and the exemption is gone. The levy then becomes payable in full, and surcharges can be added for failure to submit the required notices, with the payment schedule collapsing so the whole sum falls due at once. Our note on CIL surcharges and how to avoid them sets out the notices involved and the order they have to be served in.

Where the council operates a levy and the development is liable, price this before anything else. It routinely exceeds every other cost on the list combined.

Selling a property with unauthorised works

Conveyancing is where most homeowners discover the problem. A buyer's solicitor asks for the permission, finds none, and the transaction stalls.

Indemnity insurance is the usual proposed fix, and it has real limits. It covers the risk of enforcement action, not the cost of putting the work right, and it is typically unavailable or void where the council has already been contacted about the breach. Approaching the council to ask about a possible breach can therefore destroy the option, which is a genuine dilemma and one worth taking legal advice on rather than resolving by instinct.

A certificate of lawfulness, where the breach is old enough, is a better answer than insurance because it settles the position permanently.

Budgeting a remedy

Work through it in this order.

1. Establish the date the breach began and whether immunity has accrued.
2. Check whether the council operates a levy and whether an exemption has been lost.
3. Decide between a certificate of lawfulness and a retrospective application.
4. Price the drawings and any reports the validation list requires, such as a Planning Statement addressing the policy position.
5. Add the application fee from the current published schedule.
6. Hold a contingency for compliance works if the application fails.

One honest caveat. Regularising after the event is almost always more expensive than applying first, and it removes your ability to negotiate a design that would have been acceptable. The comparison with what a householder application actually costs done in the right order makes the point better than any argument.

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.

See PlanScope pricing if you are costing the documents for a retrospective application.