What a certificate of lawfulness is and when to apply for one

Two kinds of people look this up. One has seen "Certificate of Lawfulness" against an address on the register, or on a letter from the council, and wants to know whether they can object to it. The other has been told by an architect or a buyer's solicitor that they ought to have one. Both need the same thing first: to know what it is not. A certificate of lawfulness is not planning permission, and the council is not being asked whether it likes the scheme.

What a certificate decides

A certificate of lawfulness (the legislation calls it a lawful development certificate, and registers use both names) is a formal ruling by the council that a particular use of land, or a particular piece of building work, is lawful for planning purposes. Lawful means one of two things. Either it never needed planning permission, because it falls within permitted development or is not development at all; or it did need permission, never had it, and the time limit for the council to take enforcement action has passed.

There are two kinds, and the code on the register tells you which you are looking at.

A certificate for a proposed use or development, under section 192 of the Town and Country Planning Act 1990, asks the council to confirm that something not yet built or begun would be lawful if it were. Councils code these their own way: Cotswold logs them as CLOPUD, Worcester as CLPU, South Staffordshire as LUP.

A certificate for an existing use or development, under section 191, asks the council to confirm that something already built, or already happening, is lawful now. North Somerset's 26/P/1304/LDE, a certificate for the use of land at Backwell for airport parking, is one of these. Elsewhere you will see CLEUD, the acronym the government guidance itself uses. Our guide to reading a reference number covers the rest of the suffixes.

Either way the council is answering a question of fact and law, not of judgement. The application types guide puts it in a line: there is no planning judgement involved, only evidence. Everything below follows from that.

Proposed works: when it is worth applying

Nobody is obliged to get a certificate before doing permitted development. Plenty of rear extensions, loft conversions and garden rooms are built without one and are lawful. The reasons to apply are practical.

The first is a sale. A buyer's solicitor will ask for evidence that an extension did not need permission, and "the builder said it was fine" is not evidence. A certificate is.

The second is doubt. Permitted development rights are not the same everywhere. A condition on the original permission for a housing estate can remove them, an Article 4 direction can remove them across a conservation area, and flats have no householder rights at all. A certificate settles the question before money is spent, and if the council refuses it you have learned that a planning application is needed while the plans are still on paper.

That is what a refusal of a proposed certificate means. Cotswold refused 26/00630/CLOPUD, a section 192 certificate for a single storey rear extension at a cottage in Longborough, on 6 May 2026, six weeks after validating it. That is not a refusal of the extension. It is the council saying it was not satisfied that the extension, as described, would be lawful without permission. The applicant can redraw it to fit the rules, or apply for permission, or both. Worcester went the other way on 26/00584/CLPU, a single storey rear extension at Osborne House, Chestnut Walk, granting it on 5 August 2026, thirty days after receiving it.

Not every proposed certificate is about building. South Staffordshire's 26/00558/LUP asks whether using a house at Huntington as a children's home for up to three children is a material change of use at all. That is a question of law with a long case history behind it, and it is exactly what a certificate exists to settle.

Once granted, a proposed certificate holds unless something material changes before work starts, such as a new Article 4 direction removing the right it relied on. Trades watching an area read a grant as a signal: a certificate for a loft conversion is a job that has been decided on but not yet started, which is why they show up in the alerts for loft conversion specialists.

Existing works and uses: the time limits

An existing-use certificate is decided on evidence. The applicant has to show, on the balance of probability, that the building was substantially complete, or the use began, before the relevant time limit, and in the case of a use that it has carried on without significant interruption ever since. The council can look for evidence of its own, and if it finds any it must show the applicant and let them answer it. If nothing contradicts a precise and unambiguous account, the government guidance says there is no good reason to refuse.

The time limits changed in England on 25 April 2024, and it matters which side of that date a case falls.

So an extension finished in England in 2022 still becomes immune after four years, but the same extension finished in May 2024 will not be immune until 2034. A barn converted to a house in Wales runs on four years; the same conversion in England, if it happened after April 2024, runs on ten.

Evidence is the whole case. Dated photographs, invoices and receipts for the work, council tax and utility records, statutory declarations from people with direct knowledge, aerial imagery with a date on it. The Planning Inspectorate's guidance is blunt about it: it is not enough to say the building was finished more than four years ago. Someone has to show it.

The airport parking case at Backwell shows what an existing-use certificate turns on. The neighbours' views on traffic and noise are irrelevant, however strongly held. What decides it is whether the land has been used for customer parking continuously for ten years, and what proves that. It was received on 19 June 2026 and was still awaiting a decision in early September, past the eight week target, which is common where the evidence is contested.

Two warnings. A certificate obtained with a false statement or a withheld document can be revoked, with no compensation and no right of appeal, and obtaining one that way is a criminal offence carrying up to two years' imprisonment on indictment. And deliberate concealment of a breach can put a case outside the time limits altogether.

If it is next door: what a neighbour can and cannot do

This is the part the letter never explains. There is no statutory requirement for a council to consult neighbours or the parish council on a certificate application. Some councils notify neighbours anyway; where they do, they are inviting evidence, not opinions.

Anything about design, loss of light, overlooking, parking or noise is irrelevant and will be disregarded, because the council has no power to weigh it. That is the opposite of a planning application, where the same points are material considerations. Sending a planning objection to a certificate application achieves nothing.

What a neighbour can usefully do is supply facts. If you know when the extension went up, because you watched it, and it was more recently than the application claims, say so in writing with dates and any photographs you have. If a use has not been continuous, because the yard stood empty for two years, that is evidence. If the estate's original permission removed permitted development rights, point the council to the reference. The council is entitled to canvass this kind of evidence and must put it to the applicant.

If the council grants the certificate, there is no third-party appeal, exactly as with a planning permission. The only challenge is judicial review in the High Court, on the grounds that the council got the law wrong or followed the wrong procedure, and it has to be started within six weeks at real cost. If the council refuses and the applicant appeals, interested people can send representations to the Planning Inspectorate within six weeks of the appeal's start date, and the inspector reads them for evidence.

How long it takes and what it costs

In England the council must give a decision within eight weeks beginning the day after it receives a valid application, or within a longer period agreed in writing. Councils do noticeably better on certificates than on the applications around them. Across 24,318 lawful development decisions from 343 UK councils in the year to September 2026, the median was 55 days and 65% were decided within eight weeks. Full applications ran to a median of 69 days with 34% inside eight weeks, and householder applications to 59 days with 46%. The decision times by application type are rebuilt nightly, and every council's own page carries the same breakdown, so you can see what yours actually does rather than what it is supposed to do. If yours is running long, how long a planning decision takes covers what an extension of time means and what happens if no decision comes.

The fee is set off the planning fee rather than having a figure of its own. In England a certificate for proposed work costs half what the planning application would, and a certificate for existing work costs the same as it. From 1 April 2026 the householder planning fee is £548, so a householder certificate is £274 for proposed works and £548 for existing ones. Fees are index-linked and move every April, a further rise has been proposed for December 2026, and Wales and Scotland set their own schedules, so check the figure on the day you pay.

If the council refuses, or does not decide

A refusal is not conclusive that something is unlawful. The guidance says it may only mean that not enough evidence has been presented yet, and a fresh application with better evidence is allowed. The applicant can also apply for planning permission at the same time, without prejudice to the certificate.

The other route is an appeal to the Planning Inspectorate under section 195, which is also the route when the eight weeks pass with no decision. There is no fee, only the applicant can appeal, and in England there is currently no time limit for lodging one, though the Inspectorate says it expects an appeal within six months and has had the power since April 2024 to dismiss one the appellant is dragging out. Wales sets a six month deadline. The inspector considers lawfulness alone, on the balance of probabilities, and can grant a certificate for part of what was applied for.

Where this guide stops

A certificate covers planning law and nothing else. It does not deal with building regulations, which apply to most extensions whether or not they needed permission, nor with listed building consent, which has a separate certificate of lawfulness for proposed works decided in six weeks under its own procedure. Private matters such as restrictive covenants and the party wall are outside it entirely.

The detail above is for England unless it says otherwise. Wales, Scotland and Northern Ireland use the same idea with their own legislation, fees and time limits, and none of this is legal advice.

Keeping track

Certificate applications go on the planning register like any other, which is how they reach the applications for every council on this site with their received, validated and decided dates. To hear when one is lodged near you, or when the council decides it, set up an alert for the area rather than checking the register by hand.