The 4 and 10 year rule, the 25 April 2024 changes, and how to prove your development is now immune from enforcement.
There is no deadline for submitting a retrospective planning application, but unauthorised development becomes immune from enforcement action after a fixed period under section 171B of the Town and Country Planning Act 1990. For building works and changes of use to a single dwellinghouse, that period is 10 years from substantial completion if the work took place on or after 25 April 2024 — and 4 years if it was completed before that date. For all other changes of use, the period has always been 10 years. Once the relevant period has passed, you can apply for a Lawful Development Certificate confirming the development is now lawful, even though planning permission was never granted.
The time limits for enforcement action are set out in section 171B of the Town and Country Planning Act 1990, with transitional arrangements introduced by the Planning Act 2008 (Commencement No. 8) and the Levelling-up and Regeneration Act 2023 (Commencement No. 4 and Transitional Provisions) Regulations 2024. These regulations extended the 4 year rule to 10 years for development substantially completed on or after 25 April 2024.
The time limits set out above do not prevent enforcement action after the relevant date in three specific circumstances:
The council may take further enforcement action in respect of any breach of planning control within 4 years of any previous enforcement action (or purported action) in respect of the same breach. This stops developers from running out the clock by waiting for an earlier notice to lapse.
Where a person has deliberately concealed a breach of planning control, the local planning authority may apply to the magistrates' court for a planning enforcement order under section 171BA. If granted, this allows them to take enforcement action even after the section 171B time limit has expired. The leading case is Welwyn Hatfield BC v Secretary of State for Communities and Local Government [2011] UKSC 15, where the Supreme Court held that deliberate concealment delays the running of the time limit.
The courts have held that, where there is deliberate concealment, the time limits in section 171B do not engage at all until the breach has been discovered. This is a related but distinct principle to the planning enforcement order route and is grounded in the public policy that a wrongdoer should not benefit from their own concealment.
If your development or change of use is consistent with local planning policies, you can apply for retrospective planning permission. The council will assess the application as if the work had not yet been carried out, on its planning merits, against the same policies as a normal application. In our experience around 70% of these applications are approved.
If the development is old enough to be immune from enforcement under section 171B, you can apply for a Lawful Development Certificate (LDC) under section 191 TCPA 1990. You must provide robust evidence — dated photographs, sworn statements, utility bills, council tax records, aerial imagery — proving the development has existed without break for the required 4 or 10 year period. An LDC, once granted, is conclusive proof that the development is lawful and cannot be subject to enforcement.
Some types of development and changes of use fall under permitted development rights (PDRs) under the Town and Country Planning (General Permitted Development) (England) Order 2015, meaning they do not require formal planning permission. If you can show that your development falls within the relevant PDR, no application is needed at all — though an LDC is the safe way to confirm the position in writing.
If the unauthorised work or use does not comply with planning policies and is unlikely to gain retrospective approval, the safest option is often to revert the property to its previous condition before enforcement action begins. We will tell you honestly if this is the realistic position before you spend money on an application.
Under section 73A of the Town and Country Planning Act 1990, local planning authorities can entertain applications for unauthorised developments and assess them as if the work had not yet commenced. However, councils are under no obligation to approve such applications, particularly if the development violates planning policies or was carried out deliberately.
If your retrospective application is refused, you can appeal to the Planning Inspectorate under section 78 of the Act within six months of the refusal date. Recent legislative changes under the Levelling-up and Regeneration Act 2023 have introduced restrictions on appeals where retrospective applications have already been refused — specifically, you cannot appeal an enforcement notice on ground (a) (that planning permission ought to be granted) if a retrospective application has already been refused for the same development. This makes the first application all the more important.
The 4 year rule is gone for everything completed on or after 25 April 2024 — it is now 10 years across the board for operational development and changes of use to a dwellinghouse. Other changes of use have always been 10 years. Concealment, the second bite provision and ongoing enforcement can extend those limits in specific cases. If your development is old enough, a Lawful Development Certificate is the safest route to a clean planning record. If it isn't, a properly drafted retrospective application is the next best step.
No. There is no deadline for submitting an application. The relevant time limits relate to enforcement action by the council — once those periods have passed, the development becomes lawful and can be confirmed through a Lawful Development Certificate.
Effectively yes, for development substantially completed on or after 25 April 2024. The 4 year rule still applies to anything completed before that date, so it remains live for many older cases working their way through the system.
The starting point is the date of substantial completion, which has to be evidenced. We routinely assess the date of substantial completion using photographs, council tax records, planning history, building control records and Land Registry data. If you are not sure, ask a Chartered Town Planner for a written read on the position before you make any approach to the council.
Only in narrow circumstances. The Welwyn Hatfield principle and the planning enforcement order route both require evidence of deliberate concealment, not merely deliberate building. Knowing you needed permission and not applying is not the same thing as concealment in law — though it may attract the second bite provision if the council acted within the original time limit.
Not sure if your development is past the time limit? A Chartered Town Planner will give you an honest, written assessment before you approach the council. Get a free assessment →
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