Establish whether there is a breach
Not every building operation needs an express planning application, but work outside the limits or conditions of an applicable permission can breach planning control. The issue is what was lawfully authorised and what has actually been built or used. [3]
Collect the permission, approved drawings, amendments and relevant dates. Compare these with the work on site. Do not rely solely on a builder's assurance that the difference is small or that a neighbouring property has similar work.
What the council may do
The council can investigate, seek information and consider whether formal action is justified. Possible responses include seeking changes, inviting a retrospective application or taking enforcement action. Planning Portal explains that enforcement can ultimately require work to be put right, including removal where appropriate. [1][3]
Engage with an enquiry promptly and keep a written record. Distinguish a request for information from a formal notice requiring action by a specified date. Do not assume that a conversation about a possible application cancels a notice already served.
Retrospective permission is not a safety net
A retrospective application asks for permission for development already undertaken. Section 73A provides the statutory route, but does not promise approval because money has been spent or the building is complete. [2][4]
From publication of the NPPF on 17 August 2026, policy DM8 says that an evidence-based finding of intentional unauthorised development should carry substantial weight when deciding whether to grant retrospective permission. It is not an automatic refusal rule, but proceeding deliberately without the required permission is not a neutral planning strategy. [5]
Is it a criminal offence?
An ordinary breach of planning control is not generally a criminal offence in itself. However, failing to comply with particular notices or carrying out certain works, including unauthorised works affecting listed buildings, can create criminal liability. Do not generalise the position for an ordinary extension to every planning-related control. [1][3]
If a formal notice arrives, obtain advice immediately on its effect, compliance requirements and any appeal route. An enforcement notice has its own appeal deadline, distinct from an ordinary planning application deadline. [6]
Do not rely on waiting
The enforcement time-limit rules changed on 25 April 2024, with transitional provisions and important exceptions. The age of the property, when you bought it and when the disputed development occurred are different facts. [7]
Resolve the planning position alongside any separate building control requirements. A planning decision does not certify the structural safety or technical compliance of work already built. Where notices or possible offences are involved, obtain planning legal advice before deciding how to proceed. [8]