Retrospective planning permission explained

Retrospective planning permission is permission applied for after the work is done.

What retrospective planning permission is

Retrospective planning permission is a planning application made after development has been carried out.¹ The development may have been built without permission, or it may breach the conditions of an existing permission.

There is no separate category of "retrospective permission" in planning law. It is simply a normal planning application for work that already exists. The application is submitted, validated, consulted on, and decided in the same way as any other application.

The key difference is timing. Because the work is already built, the council and neighbours can see the actual impact rather than relying on drawings. This can work for or against you. If the work causes no harm, retrospective permission may be easier to obtain. If it does cause harm, a refusal is more likely.

Why people apply retrospectively

Common reasons for retrospective applications include:

• Genuine mistake: The applicant believed the work was permitted development but it exceeded the limits or was in a restricted area.
• Ignorance of the rules: Many people do not know that planning permission is required for certain works.
• Work done by previous owner: You buy a house and later discover an extension or loft conversion was built without permission.
• Breach of condition: Work was approved subject to conditions (e.g., matching materials, limited hours of use) but the conditions were not followed.
• Deliberate risk: Less common, but some applicants build first and apply later, gambling that the council will approve once the work is done.

Deliberate unauthorised development is risky. If refused, you must undo the work. The council may also pursue costs and prosecution. It is always better to apply before building.

How retrospective applications are assessed

The council assesses a retrospective application against the same planning policies as a normal application.² National planning policy states that the primary consideration is whether the development is acceptable in planning terms, not whether permission was sought in advance.

However, having already built can influence the decision in two ways:

Against you: If the work causes demonstrable harm (loss of neighbour amenity, overbearing impact, overlooking, traffic issues), the harm is proven rather than theoretical. This makes refusal more likely.

For you: If the work has been in place for some time without complaints, and it causes no material harm, the council may view it more favourably. Some councils take the pragmatic view that refusing retrospective permission would require enforcement and demolition, which serves no public benefit if the work is harmless.

There is no guarantee either way. Each case is decided on its merits.

The application process

A retrospective planning application follows the same process as a standard application:

1. Prepare drawings and supporting documents: Measured survey drawings showing the as-built work, site location plan, design and access statement if required.
2. Pay the application fee: The fee is the same as for a standard application. See our guide on planning permission costs.
3. Submit the application: Via the Planning Portal or directly to your local planning authority.
4. Consultation: The council will notify neighbours and consult internal departments (highways, conservation, etc).
5. Decision: The council has 8 weeks for a minor application, 13 weeks for a major application.

You can submit a retrospective application before the council discovers the unauthorised work, or in response to enforcement action. Submitting voluntarily shows good faith and may lead to a more sympathetic assessment.

Time limits and immunity from enforcement

Councils have limited time to take enforcement action against unauthorised development.³ Once the time limit expires, the development becomes immune from enforcement. It is then lawful, even without permission.

Time limits:

• 4 years for building work (extensions, outbuildings, new buildings)
• 10 years for a breach of planning control not involving building operations (e.g., change of use, breach of condition)

The time runs from the date the breach occurred, not the date the council discovered it. For building work, this is when the work was substantially completed. For a change of use, it is when the new use began.

If your unauthorised development is older than the time limit, you do not need retrospective planning permission. Instead, apply for a lawful development certificate to formally confirm the work is immune. This protects you if you later sell the property.

See our guide on the 4-year rule for more detail on how immunity works.

What happens if retrospective permission is refused

If your retrospective application is refused, the council can serve an enforcement notice requiring you to:⁴

• Remove the unauthorised work (e.g., demolish the extension)
• Alter the work to make it compliant (e.g., reduce the height, change materials)
• Cease the unauthorised use (e.g., stop using a building as a dwelling)

The enforcement notice will specify what must be done and give you a deadline to comply (usually 28 days to 6 months depending on the severity).

You have the right to appeal the refusal and the enforcement notice. The appeal is decided by the Planning Inspectorate (an independent body). If the appeal is dismissed, you must comply with the enforcement notice. Failure to comply is a criminal offence, punishable by fine.⁵

In practice, councils often negotiate. If the work can be made acceptable with minor changes, they may withdraw the enforcement notice once you make the alterations. This avoids the cost and delay of an appeal.

Should you apply retrospectively or seek a certificate?

If your work is older than the enforcement time limit, do not apply for retrospective planning permission. Apply for a certificate of lawfulness instead.

A certificate of lawfulness confirms that the development is lawful because it is immune from enforcement. It costs less than planning permission (half the fee or a fixed rate of £130 depending on the type). The council cannot refuse a certificate if the time limit has passed. They must issue it if you provide sufficient evidence.

Applying for retrospective planning permission when you could get a certificate is a mistake. Planning permission can be refused on policy grounds. A certificate cannot.

If your work is recent (within 4 or 10 years), retrospective planning permission is the correct route.

Tips for a successful retrospective application

Retrospective applications have a lower success rate than pre-emptive applications, but they do get approved. Improve your chances by:

• Be honest: Explain why permission was not sought. Genuine mistakes are treated more leniently than deliberate breaches.
• Demonstrate no harm: Show that the work does not harm neighbour amenity, character, or highway safety. Include photos, measurements, and neighbour statements if supportive.
• Offer to amend: If the work slightly exceeds policy limits, offer to reduce it (lower the roof, shorten an extension). This shows willingness to cooperate.
• Address objections: If neighbours object, address their concerns in a supporting statement. Propose screening, change materials, or limit hours of use.
• Hire a planning consultant: Retrospective applications are harder to win. A consultant can frame the application to emphasise policy compliance and minimise the breach.