Retrospective planning permission is the route you take when building work or a change of use has already happened without the consent it needed. Perhaps a builder assured you the extension was permitted development, perhaps you bought a house with an undocumented loft conversion, or perhaps the council has written to you. Whatever the trigger, the rules in England changed significantly in April 2024 and planning fees rose again on 1 April 2026, so this 2026 guide explains exactly how retrospective planning permission works, what it costs, the risks if it is refused, and how a suitably qualified, accredited surveyor can strengthen your application.
Retrospective planning permission is planning permission granted for development that has already been carried out without consent. You apply under section 73A of the Town and Country Planning Act 1990, pay the standard fee, and the council assesses the completed work against current planning policy exactly as it would a new proposal. Approval regularises the breach; refusal can lead to enforcement.
The Planning Portal makes two points that catch people out. First, a council may invite you to apply, but that is not a promise that permission will be granted. Second, if the application is refused, the council can issue an enforcement notice requiring you to put things back as they were. Retrospective permission is therefore a genuine test of whether the work is acceptable, not a paperwork exercise.
You need it whenever development that required planning permission has been carried out without it and the time limit for enforcement has not yet expired. Typical examples include:
Two situations are often confused with retrospective permission. If the work is lawful because it fell within permitted development, or because the enforcement time limit has passed, you do not need planning permission at all and should apply instead for a lawful development certificate. And if the problem is missing building control sign-off rather than planning consent, the remedy is a regularisation application for a building regulations completion certificate; planning permission never cures a building regulations breach.
The time limits decide whether a retrospective application is necessary at all. The Levelling-up and Regeneration Act 2023 replaced the long-standing four-year rule with a single ten-year period, and the change took effect on 25 April 2024. The government’s planning enforcement guidance on GOV.UK sets out the current position, which depends on when the work was finished:
| Type of breach | Substantially completed or began | Time limit for enforcement |
|---|---|---|
| Building operations (extensions, dormers, outbuildings) | Before 25 April 2024 | 4 years from substantial completion |
| Building operations | On or after 25 April 2024 | 10 years from substantial completion |
| Change of use to a single dwellinghouse | Before 25 April 2024 | 4 years |
| Change of use to a single dwellinghouse | On or after 25 April 2024 | 10 years |
| Any other change of use or breach of condition | Any date | 10 years |
In practice, an extension finished in early 2022 is already immune from enforcement and can be certified as lawful, whereas an identical extension finished in the summer of 2024 remains exposed until 2034. Dating substantial completion accurately is therefore the first job in any case, and a surveyor’s inspection of materials, weathering and construction details is often the decisive evidence.
The process mirrors an ordinary application. The main difference is that you are describing what exists rather than what you propose, and you tick the box on the form confirming that the work has already been carried out.
Retrospective permission is decided on the same policies as any other application, so the fact that the work exists carries no weight either way. Councils are specifically told not to treat an invitation to apply as a promise of approval.
There is no penalty fee. The application fee is the same as if you had applied before starting work. English fees rose by 3.8% on 1 April 2026 in line with the September 2025 CPI figure, as announced by the Planning Portal on 30 January 2026. The Planning Portal’s fee schedule for England from 1 April 2026 gives the figures below.
| Application type (England, from 1 April 2026) | Fee | Typical determination period |
|---|---|---|
| Householder: extension or alteration to a single house | £548 | 8 weeks |
| Householder: outbuilding, garden room, gates, fences or walls | £272 | 8 weeks |
| Alterations to two or more houses or flats | £1,083 | 8 weeks |
| Change of use of a building to one or more dwellings | £610 per dwelling (fewer than 10) | 8 weeks |
| Other change of use of a building or land | £610 | 8 weeks |
| Removal or variation of a condition (householder) | £89 | 8 weeks |
| Lawful development certificate for existing works (alternative route) | Same as the full application fee | 8 weeks |
Budget separately for professional drawings, a planning statement and any specialist reports. Those typically cost more than the council fee, but they are also what determines the outcome. One further cost applies in Community Infrastructure Levy charging areas: GOV.UK guidance confirms that a retrospective permission is not eligible for CIL relief or exemptions other than the minor development exemption, so a self-build or residential extension that would ordinarily have been exempt may become liable.
A refusal does not by itself require you to remove anything. The council must decide whether it is expedient to take enforcement action, and it may negotiate changes instead. If it does act, the usual tool is an enforcement notice, which specifies the breach, the steps required to remedy it, and a compliance period. Failing to comply with an enforcement notice once it takes effect is a criminal offence that can result in prosecution and an unlimited fine, and the council can carry out the works itself and recover the cost.
The appeal position changed in April 2024 and is now stricter. Under the enforcement guidance on GOV.UK, a person who has undertaken unauthorised development has only one opportunity to obtain planning permission after the event. Where an enforcement notice is issued on or after 25 April 2024, after a related retrospective application was made, and within two years of that application ceasing to be under consideration, you cannot appeal the notice on ground (a), the ground that permission ought to be granted. You can still appeal a refused retrospective application to the Planning Inspectorate in the normal way, so the practical lesson is to make the application count and to lodge any appeal promptly. The council can also decline to determine a retrospective application altogether if an enforcement notice has already been issued.
Since 25 April 2024 councils in England can issue an enforcement warning notice under section 172ZA of the Act. It is a formal invitation to submit a retrospective application where the council thinks there is a reasonable prospect of permission being granted, and it sets a deadline. There is no right of appeal against the notice itself, and issuing it counts as taking enforcement action, which stops the immunity clock. If you receive one, treat it as an opportunity: a well-prepared application within the deadline is usually far cheaper than the alternative.
Choosing the wrong route wastes the fee and can weaken your position. The comparison below shows the difference.
| Route | Use it when | Council’s test | Neighbours consulted? |
|---|---|---|---|
| Retrospective planning permission (s.73A) | The work needed permission and the enforcement time limit has not expired | Planning merits against local and national policy | Yes |
| Lawful development certificate (s.191) | The work was permitted development, or the time limit has passed | Law and evidence only, on the balance of probability | No |
| Section 73 or non-material amendment | Permission exists but what was built differs from the drawings | Whether the variation is acceptable | Depends on scale |
Unconsented alterations surface constantly in conveyancing. Sellers must answer questions about building work and consents, and a Level 3 building survey will flag any extension, dormer or outbuilding that appears to lack approval. Buyers then choose between negotiating a price reduction, taking out indemnity insurance, or insisting the seller regularises the position. Indemnity policies are invalidated if anyone contacts the council, so they are a stop-gap; for work completed after 25 April 2024 that cannot yet be immune, a retrospective application before marketing is usually the cleaner solution and supports the asking price.
Two developments this year matter for anyone weighing up a retrospective application. First, the 3.8% fee uplift on 1 April 2026 confirmed by the Planning Portal means the householder fee now stands at £548, up from £528. Second, the Local Government and Social Care Ombudsman reported in February 2026 on rising complaints about the lack of planning enforcement by councils, describing under-resourced enforcement teams, as summarised by Bevan Brittan LLP on 2 June 2026. Slow enforcement is not a reason to ignore a breach: with the ten-year rule now in force, an unauthorised extension stays exposed for far longer, and neighbours who feel ignored are increasingly likely to escalate complaints.
A retrospective application is won on evidence and detail, which is what surveyors provide. A suitably qualified, accredited surveyor can:
Surveyors regulated or accredited by bodies such as the Royal Institution of Chartered Surveyors (RICS), the Chartered Institute of Building (CIOB) and the Residential Property Surveyors Association (RPSA) work to published professional standards and carry professional indemnity insurance. That matters if a planning officer, an inspector or a future buyer later challenges the drawings or the dating evidence.
A refused retrospective application costs you the fee, months of uncertainty and, under the 2024 rules, your only chance to argue the merits. We recommend Survey Merchant because the service is built to avoid that outcome:
Ready to regularise your extension, conversion or outbuilding? Book a building surveyor with Survey Merchant or contact the team for a fixed-fee quote today.
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