Retrospective Planning Permission Time Limits

What Is Retrospective Planning Permission?

Retrospective planning permission is an application submitted after development has taken place. It allows homeowners or developers to seek legal approval for work already carried out without prior consent.

It’s not a guarantee — the local council will assess the development as if it were a standard planning application. If refused, they can issue an enforcement notice requiring you to undo the work.

People usually apply retrospectively when:

• They weren’t aware permission was needed

• They started work before receiving approval

• They bought a property with unapproved alterations

What Is the 4 Year Rule?

The 4-year rule applies to:

• Unauthorised building works (e.g. extensions, garages, outbuildings)

• Change of use to a single dwelling

If the council hasn’t taken enforcement action within 4 years of the unauthorised development being substantially completed, you may be immune from enforcement.

This means you won’t need permission, but you might still need to apply for a certificate of lawfulness to make it official — especially if you’re selling the property.

What Is the 10 Year Rule?

The 10-year rule covers:                   

• Changes of use (other than to a single dwelling)

• Breaches of planning conditions

• Ongoing unauthorised use of land or buildings

If a breach has continued for 10 years without action from the local authority, it may also become lawful.

However, the burden of proof is on you. You’ll need evidence (photos, dated receipts, sworn statements) to show the breach has existed continuously and without interruption.

How Much Will It Cost?

Retrospective planning permission costs the same as standard applications. Fees are based on the type of development — for example:

• Householder applications: ~£258

• Full planning for new dwellings: varies by size

• Certificate of Lawfulness: ~£129 (or 50% of the usual fee)

Keep in mind:

• If refused, you'll still be liable for legal or remedial costs

• You might need to hire a planning consultant or architect to strengthen your case

What Happens If There’s a Breach of Planning Conditions?

Planning conditions are legally enforceable. If you’ve breached a condition (e.g. not installing screening, exceeding height limits, or changing use), the council can issue:

• A Breach of Condition Notice

• An Enforcement Notice requiring you to comply or undo the changes

These breaches fall under the 10-year rule, so if the breach continues unnoticed for a decade, it may be lawful — but that’s risky to rely on without formal approval.

When Is Building Control Required?

Planning permission and building regulations are separate systems.

Even if you get retrospective planning permission, you’ll still need to meet building regulations. If work has already been completed, you may need to apply for a Regularisation Certificate through your local building control team.

They may inspect the work, ask for structural details, or request parts of the build be opened up. If the work doesn’t meet standards, you'll have to fix it.

What Happens If You Build Without Planning Permission?

If you build without permission, the council can:

1. Ask you to apply retrospectively

2. Refuse the application and issue an enforcement notice

3. Demand removal or restoration to original condition

You can appeal an enforcement notice, but time limits apply. Ignoring enforcement action is a criminal offence and can lead to fines or legal proceedings.

In some cases, unauthorised works can delay or block property sales, insurance claims, or mortgage approvals.

The Clock Starts When the Breach Is ‘Substantially Complete’

For the 4-year rule, time starts ticking from the date the development is substantially complete, not when the first bricks were laid. If you built an extension in stages, the council could argue the clock resets if new work is added later.

Enforcement Suspends the Clock

If the council issues an enforcement notice before the 4 or 10-year mark, that stops the time limit from applying. Even if you're close to immunity, a notice freezes your position and makes the breach unlawful again.

Lawful Use Doesn’t Mean Approved Use

Even if a development becomes immune from enforcement, it doesn’t mean it has formal planning permission. For resale, mortgages, or insurance, buyers often want a Certificate of Lawful Use or Development (CLOPUD). That means you’ll likely still need to apply — not for permission, but to confirm it’s now lawful.

Burden of Proof Is on You

To rely on the 4-year or 10-year rules, you must prove continuous use or completion — and councils can demand high-quality evidence:

• Time-stamped photos

• Utility bills

• Council tax or business rate records

• Statutory declarations (signed legal statements)

If your evidence is weak, your application might be refused even if the development is technically old enough.

Commercial vs. Residential Use

The rules differ depending on the type of use:

• Residential use as a single dwelling: 4-year rule

• Everything else (commercial, multi-unit, land use changes): 10-year rule

This often catches people out — especially with outbuildings converted into rentals, annexes, or short-term lets.

You Can’t Game the System with ‘Token’ Starts

Some people try to ‘start’ a development to keep permission alive, but the courts have made it clear — token or fake starts don’t count. Work must be real, substantial, and in line with the approved plans.

Councils Can Still Act if There’s Harm

Even if a breach is immune from enforcement, if it causes ongoing issues (e.g. blocking light, safety hazards), councils might use other powers (like Section 215 notices) to require changes.