Enforcement time limits under the 2023 Act
The Levelling-up and Regeneration Act 2023 moved enforcement immunity in England to a single ten year period. Which rule applies to your client depends on when the breach happened.
Planning enforcement time limits in England used to run on two clocks. Four years for operational development and for a change of use to a single dwellinghouse, ten years for everything else. The Levelling-up and Regeneration Act 2023 replaced that split with a single ten year period, and the practical question for anyone advising on an unauthorised building or use is now which rule applied when the breach occurred.
Get the date of the breach right first. Everything else follows from it, and a case that would have been immune under the old four year rule may still be immune, depending on the transitional provisions.
The historic four and ten year rules
Section 171B of the Town and Country Planning Act 1990 set the limits, and it did so by category rather than by seriousness.
| Breach | Old period | Ran from |
|---|---|---|
| Building, engineering, mining or other operations | 4 years | Substantial completion |
| Change of use to a single dwellinghouse | 4 years | The date the use began |
| Any other change of use | 10 years | The date the breach began |
| Breach of condition | 10 years | The date of the breach |
The four year rule for operations was the one that drove most disputes, because "substantial completion" is a question of fact. A building that is structurally finished but unfinished internally may or may not have started the clock, and the answer depends on what a reasonable observer would say about it.
The dwellinghouse limb caused more trouble still. Converting a barn or an outbuilding to living accommodation attracted the four year period, while converting a house into flats attracted ten, which produced results that were hard to explain to clients.
What the Levelling-up and Regeneration Act 2023 changed
The Act amends section 171B so that, in England, the immunity period for all breaches of planning control is ten years. The two-tier structure disappears. A barn converted without permission is now on the same footing as a change of use to an unauthorised business.
Several related changes sit alongside it. Temporary stop notices were extended, giving authorities a longer window to investigate before an enforcement notice is served. The Act also tightened the ability to appeal an enforcement notice on the ground that permission ought to be granted where an application for the same development has recently been made.
The direction of travel is consistent. Immunity is harder to acquire, investigation windows are longer, and the tactical value of running out the clock has fallen.
Commencement and transitional questions
This is where advice goes wrong, and it is worth being careful.
The change was brought into force in England by commencement regulations rather than on Royal Assent, and it applies to breaches occurring on or after the relevant date. Breaches that had already become immune under the four year rule before that date do not lose their immunity, and there is transitional provision dealing with breaches that were partway through the old four year period when the change took effect.
Read the commencement regulations themselves before advising on any case near the boundary. Two facts decide it. The precise date the amendment took effect, and the precise date the breach occurred, meaning substantial completion for operations or the date the use began for a change of use.
Where the client's recollection of dates is vague, treat the case as open. A witness statement saying "about 2019" is not a foundation for a certificate application.
Which breaches each period applies to
For breaches occurring after the change, the answer is straightforward: ten years, whatever the breach.
For older breaches, the categories still matter, and the categorisation itself is often the dispute. Three points recur in practice.
Whether works amount to operational development or a change of use can be arguable, particularly for internal works creating an additional unit. The answer changes which clock ran.
Whether a building was substantially complete on a given date is a matter of evidence, not assertion. Aerial imagery, dated photographs, delivery notes and contractor invoices carry more weight than a statement of belief.
And a breach of condition has its own period running from the breach, so a condition breached intermittently may never accrue immunity at all.
Concealment and the four year rule
Deliberate concealment can defeat immunity altogether. The Supreme Court held in the Welwyn Hatfield case in 2011 that a person who deliberately conceals a breach cannot rely on the time limit to obtain a lawful development certificate, applying the principle that nobody should profit from their own wrongdoing.
Parliament added a statutory route as well. Sections 171BA to 171BC of the 1990 Act, inserted by the Localism Act 2011, allow a local planning authority to apply to a magistrates' court for a planning enforcement order where a breach has been deliberately concealed. If the order is granted, the authority gets a fresh period in which to take enforcement action even though the ordinary limit has expired.
Concealment means something more than not telling the council. It means positive steps to hide the breach, such as a building disguised as something else, or false statements made to the authority. Simply doing the work quietly and hoping nobody notices is not concealment in the legal sense, though the line is not always obvious.
Evidencing immunity for a certificate application
The route to certainty is a certificate of lawfulness of existing use or development under section 191 of the 1990 Act. The burden is on the applicant, the standard is the balance of probabilities, and the council decides on the evidence submitted.
Build the file properly.
- A precise statement of what is claimed to be lawful, described as it would appear on the certificate.
- Statutory declarations from people with direct knowledge, covering the whole period without gaps.
- Documentary evidence tied to dates: council tax and business rates records, utility accounts, tenancy agreements, invoices, insurance schedules and bank records.
- Dated photographs and aerial imagery showing the development in place at intervals across the period.
- A chronology cross-referencing every document to the date it evidences.
Continuity matters more than volume. A gap of eighteen months with no evidence at all is where the council will focus, and an application that glosses over it invites refusal. Where the use was interrupted, say so and explain why the interruption does not break the period, rather than leaving the officer to find it.
Illustrative example: a stable block converted to a single dwelling with occupation beginning in 2016 and continuing since. Under the old four year rule the use became immune in 2020. That immunity is not removed by a later change to a ten year period, but the evidence of continuous residential occupation from 2016 to 2020 has to be complete, because if occupation was intermittent the clock may never have run.
A Planning Statement accompanying the certificate application should set out the legal framework, the chronology and the evidence schedule, rather than arguing planning merits, which are irrelevant to a certificate.
Practical advice while the position settles
Four habits are worth adopting on any file touching enforcement.
Date the breach with evidence at the first meeting, not at the application stage. Advise clients in writing that the ten year period now applies to operations, because many still work from the old four year assumption. Check the commencement position from the regulations each time rather than from a note written last year. And keep the UK planning law updates timeline in view for further changes, while citing the legislation itself in any submission.
For clients considering unauthorised works, the honest advice is that the calculation has changed. Ten years of exposure to enforcement, with a longer temporary stop notice window and a concealment route behind it, is a different proposition from four.
This is general guidance, not legal advice. Enforcement outcomes turn on dates and evidence, so take advice from a qualified professional and confirm the current commencement position before relying on any of it. A lawful development certificate is the only formal way to confirm that development is lawful.
If you need the supporting documents for a certificate or an appeal, browse the report types by category and start from the scenario.
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Frequently asked questions
Is the four year rule gone?
For breaches occurring after the Levelling-up and Regeneration Act 2023 change took effect in England, yes. All breaches now attract a ten year immunity period. Breaches that had already become immune under the four year rule keep that immunity, and transitional provision deals with breaches partway through the old period, so check the commencement regulations.
When does the clock start for unauthorised building works?
From substantial completion, which is a question of fact rather than a date on a certificate. A structurally complete building with unfinished internal fit-out may or may not have started the period. Aerial imagery, dated photographs, invoices and delivery records are the evidence that decides it, not the owner's recollection.
Can a council enforce against a concealed breach after the time limit?
Yes, in two ways. A planning enforcement order under sections 171BA to 171BC of the 1990 Act, granted by a magistrates' court, gives a fresh enforcement window where a breach has been deliberately concealed. Separately, deliberate concealment can prevent an applicant relying on the time limit to obtain a lawful development certificate.
What evidence proves immunity?
Continuous, dated evidence covering the whole period without gaps. Statutory declarations from people with direct knowledge, council tax and rates records, utility accounts, tenancy agreements, invoices, insurance and dated photographs, all cross-referenced in a chronology. Gaps of a year or more are where councils concentrate, so address them rather than skipping past.
Does a breach of condition ever become immune?
It can, but the period runs from the breach, and a condition breached intermittently may never accrue immunity because each fresh breach starts matters again. Conditions requiring something to be done and kept in place, such as a landscaping or parking condition, are particularly hard to acquire immunity against.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.