Retrospective Planning Permission: Applying After Building Without Consent

01

What Is Retrospective Planning Permission?

What is a Lawful Development Certificate?
A Lawful Development Certificate (LDC) confirms that a development is lawful — either because it complies with permitted development rules (proposed LDC: half the planning fee, so £274 for an extension or £136 for an outbuilding) or because it has become immune from enforcement through the passage of time (existing LDC: the full fee, £548 for an extension). Fees from 1 April 2026 (MHCLG schedule). It provides legal certainty and is useful for property sales.

Retrospective planning permission is simply a planning application submitted after development has already taken place. The law explicitly allows for this — Section 73A of the Town and Country Planning Act 1990 states that planning applications can be made for development that has already been carried out.

A retrospective application is processed in the same way as a normal application. The council assesses it against the same policies and material considerations. The fact that the development already exists is not in itself a reason to refuse or approve it — the application must be determined on its planning merits. One difference: under the National Planning Policy Framework published in August 2026, "if it is concluded based on evidence that the unauthorised development was intentional, that fact should be given substantial weight in considering whether to grant planning permission" (NPPF policy DM8(2)). The same applies when an Inspector considers granting permission on an enforcement appeal. So honesty and an early approach to the council matter.

Key Point: It's Legal to Apply Retrospectively

There's a common misconception that building without permission is automatically a criminal offence. In most cases, it isn't. Carrying out development without planning permission is not a criminal offence (with some exceptions for listed buildings and protected trees). It's a breach of planning control, which is a civil matter dealt with through enforcement.

The exceptions where it is a criminal offence include:

• Unauthorised works to a listed building (listed building consent is separate from planning permission)
• Unauthorised works to protected trees
• Breaching an enforcement notice
• Displaying unauthorised advertisements in certain cases

02

When Should You Apply Retrospectively?

You've Been Told to Apply

The most common trigger is receiving a letter from the council's enforcement team asking you to submit a retrospective application. This is usually the first step in the enforcement process — the council gives you the opportunity to regularise the situation before taking formal action.

You Want to Sell Your Property

When selling a property, your solicitor will check that all development has the necessary planning permissions and building regulations approval. Unauthorised development can:

• Delay or collapse a sale
• Reduce the sale price
• Make the property unmortgageable
• Require indemnity insurance (an additional cost)

Which route is better depends on the work. If it was permitted development, or has been in place long enough to be immune from enforcement, a Lawful Development Certificate for existing development confirms that without asking the council to judge the planning merits. If it needed permission and is not yet immune, a retrospective application is the way to regularise it. For minor breaches, some buyers and lenders accept indemnity insurance instead.

You Want Peace of Mind

Even if no one has complained, unauthorised development remains a risk. Neighbours change, enforcement policies evolve, and the sword of Damocles hanging over your property isn't comfortable.

🔍 Affected by this? Check planning applications near you →

03

How to Apply for Retrospective Planning Permission

The Application Process

Applying retrospectively follows the same process as a normal application:

1. Complete the application form on the Planning Portal (planningportal.co.uk)
2. Submit plans and drawings showing the development as built
3. Pay the standard fee (same as a normal application — e.g., £548 for householder, from 1 April 2026)
4. Include supporting documents as required by the validation checklist

On the application form, you'll tick the box indicating the development has already been carried out. This triggers the retrospective process.

What Drawings Do You Need?

You'll typically need:

• Site location plan (1:1250 or 1:2500)
• Block plan (1:200 or 1:500)
• Existing plans (showing the property before the development)
• As-built plans (showing the development as it currently exists)
• Elevations of the development

Since the development already exists, the "proposed" plans are actually the "as built" plans. Some councils find this confusing, so label your drawings clearly.

The Decision

The council has the usual 8 weeks (householder) or 13 weeks (major) to determine the application — the same timeframes as a normal application. Understanding why applications get refused is important context: the council cannot simply refuse because work has been done, but the same policy grounds still apply. Possible outcomes:

• Approved: The development is regularised. You'll receive a decision notice granting retrospective permission, possibly with conditions.
• Refused: The development remains unauthorised. The council may proceed with enforcement action. You have the right to appeal the refusal.
• Approved with conditions: Conditions may require modifications to the development as built. For example, obscure glazing in a window, landscaping, or boundary treatment changes.

04

What If Retrospective Permission Is Refused?

If your retrospective application is refused, the development remains unauthorised and you face several risks:

Enforcement Action

The council can issue an enforcement notice requiring you to:

• Remove the unauthorised development entirely
• Modify the development to make it acceptable
• Cease an unauthorised use

You have the right to appeal an enforcement notice to the Planning Inspectorate. But if the notice was issued after you applied for permission for the same development, you usually cannot argue on appeal that permission ought to be granted (ground (a)), unless the notice came more than two years after that application stopped being under consideration (TCPA 1990 s.174(2A)–(2AB), in force in England since 25 April 2024). So a refused retrospective application does not get a second hearing on its merits at the enforcement appeal.

The Costs of Non-Compliance

Failing to comply with an enforcement notice is a criminal offence carrying:

• An unlimited fine, in the magistrates' court or the Crown Court (TCPA 1990 s.179(8); the old £20,000 magistrates' cap was removed on 12 March 2015)
• In extreme cases, the council can enter your land and carry out the works themselves, then charge you for the cost

05

The Time Limits: 10 Years Now, With a 4-Year Exception for Older Breaches

Time limits play a crucial role in enforcement. If enough time has passed since the breach of planning control, the council loses the power to take enforcement action. Section 115 of the Levelling-up and Regeneration Act 2023 amended TCPA 1990 s.171B and, from 25 April 2024, changed these limits for England.

The Current Rule: 10 Years for Every Breach

For building operations substantially completed on or after 25 April 2024, any change of use to a single dwelling where the breach occurred on or after that date, and every other breach (other changes of use, breaches of conditions), the council has 10 years to take enforcement action. After 10 years from substantial completion (or the start of the breach), the council can no longer take enforcement action and the development becomes immune.

The Old Rule: Still Applies to Work Completed Before 25 April 2024

The old 4-year limit is saved only where the building operations were "substantially completed", or the change of use to a single dwelling "occurred", before 25 April 2024 (SI 2024/452 reg 5). Building work that started before that date but was finished after it is on the 10-year clock. For those saved cases:

• 4 years for building, engineering, mining or other operations (such as a new building or extension) and for change of use to a single dwelling, from substantial completion or the date of the breach
• 10 years for all other breaches — other changes of use and breaches of planning conditions

Wales is unaffected by the 2024 change and still applies the old 4-year/10-year split.

You can apply for a Lawful Development Certificate (LDC) to formally confirm immunity under either rule. The LDC provides legal certainty and is essential when selling the property — though immunity from enforcement is not the same thing as the development being lawful; the LDC is what actually establishes lawfulness.

Important Caveats

The time limit rules come with significant caveats:

• Deliberate concealment: If you deliberately concealed the breach (for example, building inside an existing structure so it wasn't visible), the council can apply to the magistrates' court for a Planning Enforcement Order that resets the clock. This was introduced to tackle people who deliberately hid developments until the time limit expired.
• Continuous breach: The breach must have been continuous for the full period. If you built an extension, demolished it, then rebuilt it, the clock restarts.
• Evidence: You need to prove the development has existed for the required period. Photographs, utility bills, council tax records, satellite imagery, and sworn statements from neighbours can all help.

🔍 Affected by this? Check planning applications near you →

06

Common Scenarios

Extension Built Without Permission

You built a rear extension that you believed was permitted development, but it exceeds the allowed dimensions. Your options:

1. Apply for retrospective planning permission (£548 from 1 April 2026)
2. If it's been more than 10 years (or more than 4 years if the extension was substantially completed before 25 April 2024), apply for a lawful development certificate (£548 for existing development)
3. If refused, modify the extension to comply with permitted development limits

Change of Use Without Permission

You converted your garage into a bedroom without applying for planning permission. If this constitutes a material change of use, you may need retrospective permission. However, many garage conversions don't require planning permission if the garage is attached and the external appearance doesn't change significantly.

Outbuilding Too Large for Permitted Development

You built a garden building that exceeds the permitted development limits (perhaps it's too tall, too close to the boundary, or covers too much of the garden). Apply retrospectively — many councils will approve if the impact on neighbours is acceptable.

Business Run From Home

You started a business from home that's grown beyond what's incidental to the residential use. A change of use may have occurred, requiring planning permission. This is particularly relevant if customers visit the property, deliveries are frequent, or the business dominates the property's character.

07

Tips for a Successful Retrospective Application

1. Act promptly when contacted by the council — cooperation goes a long way
2. Be honest in your application — don't try to minimise what's been built
3. Commission accurate drawings of the development as built
4. Address neighbour concerns proactively — if neighbours complained, try to resolve issues
5. Consider modifications — offering to change elements (such as adding obscure glazing or reducing height) can turn a refusal into an approval
6. Get professional advice — a planning consultant can assess your chances and advise on the best strategy