Completion notices and unfinished planning permissions

A completion notice is the mechanism that lets a local planning authority bring an unfinished development to an end. Once a permission has been lawfully implemented it does not expire, so a part built scheme can sit on a site indefinitely. Sections 94 to 96 of the Town and Country Planning Act 1990 give the authority a power to serve notice that the permission will cease to have effect after a stated period, which cannot be less than 12 months. The Levelling-up and Regeneration Act 2023 changed how that power operates, and the commencement position needs checking before anyone relies on either version.

What the notice actually does

A completion notice states that the planning permission will cease to have effect at the end of a specified period unless the development is completed before then. If that happens, the permission dies.

The important qualification is what survives. Works lawfully carried out before the notice bites remain lawful. What disappears is the authority to finish. A developer left holding a half built frame has no permission to complete it and would need a fresh application, on current policy, with current fees, against a current development plan.

That is a serious consequence, and it explains why the power has historically been used sparingly. It is a lever for negotiation far more often than a notice that runs its course.

When an authority can use it

The statutory trigger is that development has begun and the authority is of the opinion that the development will not be completed within a reasonable period. Both limbs matter.

Development having begun means a material operation under section 56 of the 1990 Act has taken place: digging foundation trenches, laying underground mains or pipes, constructing a road, a material change of use, or works of construction in the course of erecting a building. A token start, the trench dug in the last week of the three year period, is enough to implement the permission and therefore enough to bring the site within the completion notice regime.

The reasonable period judgement is the authority's, and it is where most disputes sit. A site paused for six months because a main contractor failed is a different case from a site where nothing has moved for four years and the owner is waiting for values to rise.

The procedure and the minimum period

The notice specifies the period after which the permission will cease to have effect, and that period cannot be shorter than 12 months from the notice taking effect. In practice authorities often specify longer where a genuine construction programme exists.

Under the original regime the notice had no effect unless it was confirmed by the Secretary of State, and the person served could require a hearing before an inspector. That confirmation stage was the main reason the power was rarely used, since it added a lengthy central process to a local decision.

The authority can also withdraw a completion notice at any time before the period expires, which is the usual outcome where the notice has done its job and work has restarted.

What the 2023 Act changes

The Levelling-up and Regeneration Act 2023 reforms the completion notice regime as part of a wider set of build out measures, alongside provisions on commencement notices and reporting on the progress of development. The most significant change is procedural: the requirement for the Secretary of State to confirm a notice is removed, so an authority serves the notice itself and the person served has a route of challenge afterwards rather than a confirmation stage beforehand.

As at 17 September 2026, the planning provisions of that Act have been brought into force in stages, and not every measure is yet live. Check the commencement information on the Act's page on legislation.gov.uk for the specific sections before advising a client, and treat any secondary summary, including this one, as a prompt to verify rather than as the current law. You can follow reform news on the planning law timeline.

The practical effect of removing the confirmation stage is that completion notices become a usable tool rather than a theoretical one. Authorities under pressure on housing delivery have an obvious interest in that.

The link with commencement and lapse

It helps to keep three separate time limits apart.

A permission that is never implemented simply lapses at the end of the commencement period, and no notice is needed. A permission that is implemented cannot lapse, which is the gap the completion notice fills. Phasing conditions and conditions requiring a schedule of works sit alongside both and are enforced in the normal way.

Part built schemes and plot sales

Two situations deserve attention.

On a serviced plot development, a completion notice served on the wider permission can affect individual plot purchasers who have bought on the strength of it. Anyone buying a plot should ask whether a completion notice has been served or threatened, and should check the planning history rather than relying on the seller's summary.

On a partly built site sold as an asset, the value depends on the ability to finish under the existing permission. Due diligence should test whether the permission was lawfully implemented, whether any pre commencement conditions were discharged before the material operation, and whether the authority has raised completion. An unimplemented pre commencement condition can mean the works were never a lawful start at all, which is a worse problem than a completion notice.

An illustrative example: a permission for nine dwellings, implemented by foundation trenches in the final weeks of the three year period. Four plots were built and sold, and the remaining five sat as excavated ground for three years. The authority indicated it was considering a completion notice. The developer responded with a programme, a revised phasing condition application and evidence of a signed building contract, and the notice was not served. That is how the power usually works.

Challenging a notice

The route depends on which version of the regime applies to the notice. Under the original provisions, the confirmation process before the Secretary of State was the point at which the case was argued, with a right to a hearing. Under the reformed provisions the challenge comes after service.

Either way the arguments are the same in substance. Whether development has in fact begun. Whether the period allowed is reasonable given the nature of the works outstanding. Whether the authority took account of matters it should have, including the reasons for delay and any evidence of a genuine intention and ability to complete. Judicial review remains available where the decision to serve is legally flawed.

Keep records that support the case before you need them: contracts, programmes, finance correspondence, discharge of condition approvals and site records of work carried out.

Practical steps on a stalled site

1. Confirm whether the permission was lawfully implemented, including whether pre commencement conditions were discharged first.
2. Establish what remains outstanding and produce a realistic programme with dates.
3. Talk to the case officer before they write to you, and put the programme in writing.
4. Consider whether a section 73 application to vary a phasing or time condition solves the problem more cleanly.
5. Where the scheme is no longer deliverable as consented, test whether a fresh or amended application is better than defending the old one.
6. Budget for the current fee schedule and current policy requirements if a new application becomes likely, including the biodiversity gain condition.

That last point catches people out. A permission granted before mandatory biodiversity net gain took effect does not carry the condition, and a replacement permission granted now generally will. The same applies to fees, which are indexed annually, and the article on planning fees and annual indexation explains the mechanism. Where the site includes vacant buildings, the article on vacant building credit is worth reading before you assume the affordable housing position is unchanged.

The document pack for a replacement application is usually larger than the original, and the report index shows what the current requirements tend to pull in.

This is general guidance rather than legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

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