Homeowner Guide June 5, 2026 2 min read
Lawful Development Certificate Explained: A 2026 Homeowner Guide
What a Lawful Development Certificate is, the two types, when to apply, what it costs you in time, and why buyers ask for one.
The short answer
A Lawful Development Certificate is a formal document from your local planning authority confirming that a building project, or an existing use, is lawful and did not, or does not, need planning permission. It is most often used to prove that work is permitted development. It is not compulsory, but it gives you certainty, and it is frequently requested by buyers and their solicitors when you sell.
If your project is permitted development, a certificate turns "we think this is allowed" into a document you can rely on. A Homeowner Planning Review tells you whether your project is likely permitted development in the first place, for £249, before you apply.
The two types
- Proposed works (before you build). You ask the council to confirm that what you intend to do would be lawful permitted development. This is the safer route: you get certainty before spending on the build.
- Existing works or use (after the event). You ask the council to confirm that something already built, or an existing use, is lawful, often because it was permitted development or because enough time has passed for it to become immune from enforcement.
Both are applications to your local planning authority under the Town and Country Planning Act 1990. You submit plans and evidence, the council assesses whether the facts meet the legal tests, and, if satisfied, it issues the certificate.
Why bother if it is not required
- Selling. Buyers’ solicitors routinely ask for evidence that past work was lawful. A certificate avoids a sale stalling over an unproven extension or loft conversion.
- Certainty before you build. A proposed-use certificate confirms your reading of the permitted development rules before you commit, which is reassuring if the limits are close.
- Peace of mind. It removes the risk of a later dispute about whether you needed permission.
What it is not
A Lawful Development Certificate is not planning permission. It does not approve the merits of a design; it confirms that permission is not needed. It is also separate from Building Regulations approval, which you will usually still require. And it only holds if the facts you give are accurate, so the evidence matters.
Before you apply
The first question is always whether your project actually is permitted development. Get that right and the certificate is straightforward; get it wrong and you may need a full application instead. A Homeowner Planning Review checks your property and project for £249 in 48 hours, and you can read how we verify every report. See also our permitted development rights guide.
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