Do you need a lawful development certificate?

What a proposed certificate gives you

(4) The lawfulness of any use or operations for which a certificate is in force under this section shall be conclusively presumed unless there is a material change, before the use is instituted or the operations are begun, in any of the matters relevant to determining such lawfulness.

"Conclusively presumed" means the council cannot later take enforcement action against the work described, if you build what the certificate describes.

The protection has a limit people miss. It holds only if nothing relevant changes before you start. Government guidance gives two examples of a material change: an article 4 direction removing the right, and a change to the permitted development rules themselves. The rules do change: on 27 August 2026 the Order was amended to rewrite the limits for solar panels on houses. Once you have a certificate, start.

A certificate covers planning only. It does not deal with Building Regulations, listed building consent or any other regime (planning practice guidance, paragraph 004).

When it is worth having

• The design is close to a limit, such as a rear extension at 2.9 m, or a garden room whose height depends on how the ground is read.
• The original house is unclear because of earlier extensions. See the original house.
• You expect to sell. The Planning Portal gives, as an example, an owner who discovers during a sale that planning permission was never granted and needs to show the buyer that no enforcement action can be taken.
• A neighbour disputes the work. Third-party views on the merits are irrelevant to the decision (guidance, paragraph 008).
• The work was done years ago without permission. A section 191 certificate can confirm it is now immune from enforcement. See the 10-year enforcement rule.

What it costs, from 1 April 2026

Draft regulations would raise the householder application fee to £575 from 8 December 2026. They had not been made when this page was checked. A proposed certificate would still be half the application fee.

What to submit

Article 39 of the Development Management Procedure Order 2015 requires the application form, a plan to an identified scale showing north, the evidence you rely on, and a statement of your interest in the land and of anyone else's.

For a proposed certificate the evidence is mainly drawings. Guidance says the proposal must be described "with sufficient clarity and precision to enable a local planning authority to understand exactly what is involved". In practice that means existing and proposed plans and elevations, every dimension the relevant Class tests, a note of earlier extensions, and a short statement naming the Class you rely on.

For an existing certificate the evidence has to show when the building work was substantially completed, or when the use began and that it has carried on since. The council decides on the balance of probability, and guidance says that if it has no evidence to the contrary, precise and unambiguous evidence from you is enough.

Decision, refusal and appeal

The council must decide within 8 weeks of receiving a valid application, or a longer period you agree in writing (article 39(10)). It does not have to consult neighbours, and planning merits play no part: the only question is whether the work would be lawful.

A refusal is not conclusive that the work is unlawful. Guidance says it may mean the evidence was not enough, and you can apply again with more. You can also appeal under section 195. The Planning Inspectorate counts certificate appeals with enforcement appeals, and that group, decided by written representations in June 2026, took a median of 67 weeks. A better-evidenced second application is usually quicker.

A certificate can be revoked if a statement was false or information was withheld (section 193(7)), and knowingly or recklessly making a false statement to obtain one is an offence (section 194).

What this means for you

Apply once the design is fixed, and start work while the certificate still reflects the law. Check the proposal first with the permitted development checker. If the answer is no, you need a householder application instead.