Enforcement and works claimed as permitted development

An enforcement permitted development dispute usually starts with a letter saying the council has reason to believe a breach of planning control has occurred, and asking you to explain. The critical point, and the one homeowners get wrong, is that the burden of proving the works were permitted development falls on you, not on the council. The officer does not have to prove the extension was unlawful. You have to show, on the balance of probabilities, that it met every limit and condition of the class you are relying on.

That sounds unfair until you consider the alternative. The Order grants permission subject to conditions, so anyone claiming its benefit has to show the conditions were met.

How a dispute usually arises

Nearly always a complaint. A neighbour notices building work with no notice on a lamp post and no application on the council's website, and rings the planning enforcement team. An officer looks at the aerial imagery, compares it with the planning history, and visits.

Occasionally it surfaces years later on a sale. The buyer's solicitor asks for evidence that a rear extension or a loft conversion was authorised, finds nothing, and the transaction stalls until something is produced. That version is more common than enforcement, and it is the reason to keep records even when you are confident the works were permitted.

The other route is a condition. Where permission was granted and a condition was not complied with, the council can serve a breach of condition notice, which works differently and bites harder, as explained in the guide to why a breach of condition notice has no appeal route.

Who carries the burden of proof

On an enforcement appeal, ground (c) is that the matters alleged do not constitute a breach of planning control, which is the ground you use when you say the works were permitted development. The appellant carries the burden on that ground and the standard is the balance of probabilities.

In practice that means measurements. If you are relying on Class A of Part 1 of Schedule 2 to the General Permitted Development Order for a rear extension, you need to show the depth from the original rear wall, the height at the eaves, the maximum height, the materials, whether the extension is on a designated site, and whether any part extends beyond a side elevation. The word original does a lot of work: it means the dwellinghouse as it stood on 1 July 1948, or as built if later, so an extension added by a previous owner in 1985 counts against your allowance.

Assertion does not discharge the burden. A dimensioned survey drawing of what was built, prepared after the event, usually does.

Enforcement time limits and immunity

Time limits are set by section 171B of the Town and Country Planning Act 1990, and they changed. Historically the limit was four years for building and engineering operations and for a change of use to a single dwellinghouse, and ten years for other breaches. The Levelling-up and Regeneration Act 2023 replaced that with a single ten year limit in England.

Two practical consequences follow, and both need checking against the transitional provisions that apply to the dates in your case.

• The four year rule can still be relevant to older breaches, depending on when the works were substantially completed and when the new limit began to apply.
• For anything recent, assume ten years.

Immunity is not the same as permission. Once a breach is immune from enforcement, section 191 of the 1990 Act allows the position to be formalised through a certificate of lawfulness, and section 191(2) then makes the development lawful for all planning purposes. Until that certificate is issued, you have an argument rather than a document, and a buyer's solicitor will treat it as such.

Responding to a planning contravention notice

A planning contravention notice under section 171C requires information about the ownership and use of the land, the operations carried out and the dates. Answer it.

Failure to respond within 21 days, without reasonable excuse, is a criminal offence, and giving false information knowingly is a separate one. The answers can be used in evidence later, which is the reason to be accurate rather than evasive and the reason to take advice before returning it if the position is complicated.

Three habits help. Answer what is asked and nothing more. Give dates you can evidence and say when you cannot be precise. Attach the documents rather than describing them.

Applying for a certificate after the event

Section 191 covers an existing use, operation or activity, and section 192 covers a proposed one. For works already built, section 191 is the route, and the application is decided on evidence rather than on planning merits. The council cannot refuse it because it dislikes the extension.

Precise and unambiguous evidence from the applicant can be enough on its own where there is nothing to contradict it. Vague recollection will not do, and nor will a statutory declaration that simply asserts the conclusion. The same evidential discipline that decides whether a garden building was ever incidental to the house, discussed in the guide to when a garden office stops being incidental, applies here.

Appeal grounds on an enforcement notice

An enforcement notice can be appealed under section 174(2) on seven grounds, and more than one can be pleaded together.

1. Ground (a): that planning permission ought to be granted. This carries a deemed application and a fee.
2. Ground (b): that the matters alleged have not occurred.
3. Ground (c): that the matters do not constitute a breach of planning control, which is the permitted development argument.
4. Ground (d): that at the date the notice was issued, enforcement was already out of time.
5. Ground (e): that copies of the notice were not served as required.
6. Ground (f): that the steps required exceed what is necessary to remedy the breach.
7. Ground (g): that the compliance period is too short.

Ground (f) is undervalued. Where a notice requires complete demolition of an extension that is 200 millimetres too deep, an appeal on ground (f) asking that the steps be limited to reducing the depth often succeeds where a challenge to the breach itself would fail. Appeal before the notice takes effect, because a notice that has come into force cannot be appealed and non-compliance becomes an offence. Where the dispute turns on whether something sits within the curtilage or which elevation is the principal one, the tests are those set out in the guide to curtilage and principal elevation in Class A cases.

Keeping records that settle the question

Build the file while the scaffolding is up, because the cost of doing it later is far higher.

Photograph the original building from fixed positions before work starts, with something of known size in frame. Photograph the setting out, the foundations and the completed shell with dates. Keep the builder's quotation, invoices and the final account. Note the measurements that matter for the class you are relying on, specifically the depth beyond the original rear wall, the eaves height, the ridge height, the distance to the boundary and the total area of ground covered by buildings within the curtilage.

Then have the position confirmed. A certificate under section 192 before you build, or under section 191 afterwards, is the only formal way to establish that works are lawful, and it costs a fraction of an enforcement appeal. A short Planning Statement setting out the class relied on, the measurements and the evidence is what turns a pile of documents into an application an officer can grant.

Enter your postcode on PlanScope to see which documents a certificate or retrospective application would need.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. A lawful development certificate is the only formal way to confirm that works are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.