Retrospective Planning Permission: Can You Apply After Building?

What is retrospective planning permission, when can you apply, and what are the risks of building first and applying later?

Retrospective planning permission is the process of applying for planning approval after development has already been carried out. While it is legal to submit a retrospective application, building without permission is a risky strategy with potentially serious consequences.

What Is Retrospective Planning Permission?

A retrospective planning application is identical to a standard application in all respects - the same forms, the same fee, the same assessment criteria. The only difference is that the development has already been built. The council must assess the application on its planning merits, just as it would any other application.

The council cannot refuse a retrospective application simply because the development was built without permission. Equally, they are not obliged to approve it just because the work is already done. The assessment is the same as if the application had been submitted before construction.

Common Situations

Retrospective applications arise in various situations:

• Genuine mistake - the homeowner believed the work was permitted development but it was not (common with extensions that slightly exceed PD limits)
• Deviation from approved plans - the builder made changes during construction that differ from the approved drawings
• Change of use - a garage was converted to a living room, or a house was converted to an HMO, without realising permission was needed
• Discovered during a sale - a solicitor identifies unauthorised work during the conveyancing process
• Enforcement response - the council has identified a breach and the owner applies retrospectively to try to regularise it

How to Apply

The process is the same as a standard planning application:

1. Submit an application - use the standard form on the Planning Portal or your council's website. Tick the box indicating the development has already been carried out
2. Pay the standard fee - the same fee as a prospective application. There is no penalty fee for retrospective applications
3. Provide drawings - submit "as-built" drawings showing the development as it currently exists (not as you plan to build it)
4. Consultation - the council will consult neighbours and statutory consultees in the usual way
5. Decision - the officer will assess the application against planning policy and make a recommendation

What If It's Refused?

If a retrospective application is refused, the council can take enforcement action requiring you to:

• Remove the development - demolish the extension, restore the building to its previous state
• Modify the development - alter the development to make it acceptable (reduce height, add screening, etc.)
• Cease the use - stop the unauthorised use and revert to the previous use

You can appeal the enforcement notice to the Planning Inspectorate. You can also appeal the refusal of the retrospective application through the normal appeals process.

Risks of Building Without Permission

Building first and applying later is risky for several reasons:

• Refusal and demolition - if the retrospective application is refused and enforcement action follows, you may have to demolish at your own cost
• No negotiation - with a prospective application, the officer can suggest amendments before you build. With a retrospective application, the development is already fixed - there is less room for negotiation
• Mortgage and insurance issues - mortgage lenders and insurers may have concerns about unauthorised development
• Difficulty selling - solicitors will flag unauthorised work during conveyancing, potentially delaying or preventing a sale
• Neighbour relations - building without permission often damages relationships with neighbours, who may feel bypassed

Enforcement Time Limits

There are time limits after which the council can no longer take enforcement action:

• 4 years - for unauthorised building operations and for change of use to a single dwelling
• 10 years - for all other breaches, including changes of use and breaches of conditions

Once the time limit has passed without enforcement action, the development becomes immune from enforcement. You can then apply for a Certificate of Lawfulness to formally confirm that the development is lawful by virtue of time. This is a legal document - equivalent in effect to planning permission - and is essential for selling a property with previously unauthorised work.

Important: the time limit runs from substantial completion of the development, and the burden of proof is on the applicant to demonstrate when the work was completed. Keep evidence - dated photographs, building receipts, utility connections - in case you need to prove the timeline.

Certificate of Lawfulness vs Retrospective Permission

These are different applications for different situations:

Professional Advice

If you have unauthorised development on your property, seek professional advice before acting. A planning consultant can assess whether:

• The development is actually permitted development (and therefore lawful without any application)
• A retrospective application is likely to succeed
• A Certificate of Lawfulness is the better route (if the time limit has passed)
• Any modifications could make the development acceptable