Enforcement time limits and what they mean for neighbours

If a breach of planning control goes unchallenged for long enough, the council loses the power to act on it and the development becomes lawful. For neighbours watching an unauthorised extension go up, or a house quietly turn into six flats, that is the rule that matters most, and the clock is usually already running by the time anyone notices. Planning enforcement time limits changed in England in 2024, and a lot of advice online still describes the old position.

The short version: for breaches in England occurring on or after 25 April 2024, the limit is ten years for everything. Breaches that had already become immune before that date stay immune.

Why time limits exist at all

Planning enforcement is discretionary. Councils are not obliged to take action, and the legislation gives them powers rather than duties. Time limits sit on top of that discretion to stop indefinite uncertainty about the status of buildings and uses.

The policy reasoning is about property transactions as much as fairness. A purchaser needs to know whether a conservatory built 15 years ago can be pulled down, and a lender needs to know whether the flat it is lending against exists lawfully. Without a cut-off, every title would carry an open question.

That reasoning does not make the outcome feel just when the building next door is two metres taller than the approved drawings. It explains why the limits are short rather than long, and why evidence of when works began is so heavily contested.

The limits as they now stand

Section 171B of the Town and Country Planning Act 1990 sets the periods. The Levelling-up and Regeneration Act 2023 amended it for England so that a single ten year period applies to all breaches, replacing the previous split.

The transition matters. If an extension was substantially completed in 2019, it had already gained immunity under the four year rule before the change took effect, and the amendment does not revive the council's power. If it was completed in 2022, the position depends on whether four years had run before 25 April 2024, and that is a question to put to the council rather than to work out from a table.

Operational development runs from substantial completion, not from the first spade in the ground. A structure left unfinished for years may still be within time.

The deeper treatment of the old and new periods, including how the transition works, is in immunity from enforcement and the four and ten year rules.

Concealment stops the clock being a reward

Where a breach has been deliberately concealed, the council can apply to a magistrates' court for a planning enforcement order under sections 171BA to 171BC of the 1990 Act. If granted, it opens a fresh period during which enforcement action can be taken, even though the ordinary time limit has expired.

Concealment means active steps to hide the breach, not merely failing to advertise it. Building a dwelling inside a structure that looks like a hay barn is the sort of case the provisions were written for. Putting up an extension in plain view that nobody complained about is not.

For a neighbour, the practical point is that suspicion of concealment should be reported with evidence rather than as an allegation. Dates, photographs and a description of what was visible from where carry the argument.

Listed buildings and other regimes are different

Immunity under section 171B applies to planning control. It does not touch other regimes, and the most important exception is listed buildings.

Unauthorised works to a listed building are a criminal offence under the Planning (Listed Buildings and Conservation Areas) Act 1990, and listed building enforcement notices are not subject to the same time limits. Works carried out 20 years ago without listed building consent can still be the subject of enforcement action, which surprises owners and neighbours alike.

Protected trees, advertisements, and breaches of other consent regimes each run on their own rules. So do building regulations, covenants and highway consents, none of which is affected by planning immunity.

Evidence of when works began or a use started

Almost every disputed immunity case turns on dates, and the person asserting immunity has to prove it on the balance of probabilities.

The evidence councils and inspectors find useful includes:

• Dated aerial imagery and historic satellite views showing the structure present or absent.
• Council tax and business rates records, which fix when a separate unit came into existence.
• Utility accounts, tenancy agreements and rent books for a change of use.
• Building control records and completion certificates.
• Invoices and delivery notes from the build.
• Sworn statements from neighbours, which carry real weight when they are specific about dates and what was seen.

Neighbours are often the best source of the last item. A statement saying the flats were occupied from a particular autumn, supported by a recollection of a specific event, is more useful than a general impression.

Where a use has stopped and restarted, the count may have been interrupted, and the position gets technical quickly. That is the point to take advice.

What immunity does and does not mean

Once the period has run, the council cannot take enforcement action over that breach. The owner can apply for a certificate of lawfulness of existing use or development under section 191 of the 1990 Act, and a granted certificate is conclusive evidence of lawfulness for the matters it covers.

Immunity does not mean the development was approved, and it does not mean any of the following:

• That further works are lawful. An immune extension does not carry the right to extend it again.
• That other regimes are satisfied, including building regulations and listed building consent.
• That conditions on any related permission are unenforceable, because a condition breach has its own ten year period which may have started later.
• That the use can intensify. A material change in the character of the use can start a fresh breach.

For neighbours, that last point is the useful one. An immune situation is immune as it stands. Any change to it can reopen the position.

What a neighbour can actually do

Report the breach in writing as soon as you notice it, because the date of your report becomes part of the council's record. The council's enforcement team will decide whether to investigate, and reporting a breach of planning control to the council sets out what a useful report contains.

Ask for the case reference and for confirmation of the date the complaint was received. Provide dated photographs from the start, not later, because photographs taken today prove nothing about last year.

Understand the limits of your position. A neighbour cannot compel enforcement action, cannot appeal a decision not to enforce, and cannot appeal a grant of planning permission either, as explained in whether neighbours can appeal a planning permission. The routes that exist are complaint to the council, complaint to the Local Government and Social Care Ombudsman about maladministration, and in narrow circumstances judicial review.

And act early. The difference between reporting something in its first year and reporting it in its ninth is the difference between a live case and a certificate application you will be invited to comment on.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

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