Retrospective Planning Permission: What to Do When the Work Is Already Built

What retrospective planning permission is, and what it is not

Section 73A lets a council grant permission for development carried out before the date of the application. It covers work done without permission, work that outlived a temporary permission, and work done in breach of a condition. The permission can take effect from the date the work was carried out.

Applying is not an admission of guilt and carries no fine. Building without permission is not a criminal offence in itself. The offences come later: ignoring an enforcement notice, a stop notice or a breach of condition notice.

Government planning practice guidance on enforcement, updated 6 May 2026, goes further. Councils should invite an application where the work has a reasonable prospect of being acceptable.

Two more things it is not. It is not a route to Community Infrastructure Levy relief: a retrospective permission is generally not eligible for CIL exemptions. And it is not a sign-off under the Building Regulations, which is a separate process covered below.

Three routes: apply, certify, or wait

The right route depends on one date: when the work was substantially completed, or when the use began. Enforcement time limits changed on 25 April 2024 under the Levelling-up and Regeneration Act 2023.

Once you know the date, there are three routes.

1. Certificate of lawfulness. If the time limit has passed, apply under section 191. The council must issue the certificate if your evidence shows the use or works were lawful on the date you applied.
2. Retrospective application. If the time limit has not passed and the work is acceptable in planning terms, apply under section 73A. The drawings show the work as built.
3. Wait. Doing nothing is a risk, not a plan. The council can act at any time within the limit, and a buyer's or lender's solicitor will find the gap in the paperwork.

Our guide to outline, full and certificate of lawfulness applications explains what evidence a certificate needs. The best evidence is dated: invoices, photographs, council tax records, aerial imagery and statutory declarations from people who saw the work.

The enforcement process, step by step

Councils rarely start with an enforcement notice. The usual sequence runs from a letter to a notice, and each step has its own deadline.

1. Complaint and site visit. Most cases start with a neighbour. An officer visits and compares what is built with the planning history.
2. Planning contravention notice. A formal request for information. You have 21 days to return it. Not answering, or answering falsely, is an offence.
3. Enforcement warning notice. New since 25 April 2024. It says the work has a reasonable prospect of consent and gives you a date to apply by. There is no appeal against it.
4. Temporary stop notice. Used where the council wants an activity stopped at once. It lasts up to 56 days in England.
5. Enforcement notice. It states the breach, the steps to put it right and the time allowed. Copies must be served within 28 days of issue, and at least 28 days before the date it takes effect.
6. Compliance period. Once the notice takes effect and the period runs out, the owner is in breach. Failing to comply is an offence punishable by a fine, and the court must consider the financial benefit gained.

Expedient is the test. A council must be satisfied there is a breach and that a notice is expedient, judged against the development plan. A small overrun of a permitted development limit may never be worth a notice. A new floor of flats, a commercial kitchen extract or a change of use that affects neighbours usually will be.

Appealing an enforcement notice: the seven grounds

An enforcement notice can be appealed to the Planning Inspectorate. The appeal must be received before the date the notice takes effect, which is at least 28 days after service. The Inspectorate's procedural guide, updated 22 April 2026, says there is no discretion: a late appeal is turned away. Appeals are submitted online only.

Ground (a) is the planning merits. It carries a fee of twice the planning application fee for the same development, paid to the council.

Since 25 April 2024 there is a catch. If the council issued the notice after you made a related application, ground (a) is not available for two years after that application was decided. The merits are then argued through a planning appeal against the refusal instead.

Timescales are long. The Planning Inspectorate's statistical release of 22 October 2026 gives a median of 66 weeks from a valid enforcement appeal to a decision. Planning appeals by written representations took a median of 18 weeks. Our planning appeal guide for London covers the planning route in detail.

What a refusal means: appeal, alter, or remove

A refused retrospective application is a refusal like any other. You have six months to appeal to the Planning Inspectorate, or 12 weeks for a householder application. If an enforcement notice has also been served, the enforcement deadline governs, and it is shorter.

1. Appeal. Right where the officer's report misreads policy or the committee went against its officer. For applications made from 1 April 2026, most appeals cannot add new evidence, so the application itself is the case.
2. Alter. Often the cheapest route. Councils refuse on specific points: height, depth, a window, materials, a roof terrace, noise from plant. A revised scheme that removes the point goes in as a new application.
3. Remove. The last resort, and what an enforcement notice requires if nothing else succeeds.

For a commercial or mixed-use building the alteration route usually needs construction, not just drawings. A lowered parapet, obscured glazing, a relocated flue, an acoustic enclosure around plant, a mezzanine cut back from the shopfront. Having the designer and the builder in one team keeps the revised drawings buildable and priced before they are submitted.

What retrospective planning permission costs

There is no separate fee for a retrospective application. You pay the fee for the application the work would have needed. The figures below are the council fees in England from 1 April 2026; a rise is proposed from 8 December 2026.

The full schedule and the proposed December figures are in our guide to planning application fees in 2026.

The fee is the small part. Professional costs cover a measured survey of what was built, as-built drawings and a planning statement. Add any reports the council asks for: daylight, noise, heritage, transport.

The works are the real variable. Nothing if consent is granted as built. An element rebuilt if it is not. The whole thing taken down if a notice stands and every appeal fails.

Listed buildings and the Building Regulations: two separate problems

Retrospective planning permission does not cover a listed building. Unauthorised works that affect its character are a criminal offence under section 9 of the Planning (Listed Buildings and Conservation Areas) Act 1990. The penalty on indictment is up to two years' imprisonment, a fine, or both.

There is no time-limit immunity for a listed building. Retrospective listed building consent can be applied for, but take advice before anything else.

Nor does it cover the Building Regulations. Work done without building control approval needs a regularisation certificate under regulation 18 of the Building Regulations 2010. The authority can require the work to be opened up, tested and sampled.

The certificate is evidence, not conclusive proof, that the work complies. Buyers' solicitors ask for both documents, so plan for both at the start.

How we help: survey, redesign, cost, apply, build

Our planning work starts from the building, not from the forms. Retrospective cases are won on accurate as-built information and a realistic view of what the council will accept.

1. Survey what was built. A measured survey and as-built drawings, so the application describes the real building.
2. Design the compliant version. Where the work as built will not get consent, we draw the version that will and show the difference.
3. Cost the alterations. Each option priced before you choose, so the planning decision is also a budget decision.
4. Run the application. Planning statement, submission, officer negotiation, and the appeal if one is needed.
5. Deliver the works. The same team builds the alterations, as a construction company in London with around 60% of its labour in-house.

Homeowner with a single rear extension? The same rules apply, and the planning route is usually simple enough for an architect alone. We take on construction projects from £100,000. For a small extension our advice is short: apply early, and apply before the notice.

If the building is commercial or mixed use, or the fix needs construction, tell us what was built and when. We check the planning history and the time limits, and come back with the route and a price for the works.