Five Minutes On… Completion Notices

Completion Notices are one of those planning tools that rarely appear in everyday conversation but can have a real impact on buyers, developers and anyone relying on an existing planning permission.

They’re often misunderstood, especially because the name sounds similar to completion certificates – but they are entirely different things. Here’s a quick, clear guide for clients and conveyancers on what Completion Notices are, when they’re used and why they matter in a property transaction.

What Is a Completion Notice?

A Completion Notice is issued by a local planning authority when it believes that development which has started will not be completed within a reasonable period.

The effect of the notice is to set a deadline: if the development is not finished by the date given, the planning permission will be treated as having expired for any incomplete work. In other words, the permission is “switched off” for the unfinished parts of the project. A Completion Notice does not force anyone to finish the work, it simply removes the protection of the existing planning permission after a specified date.

When Are Completion Notices Used?

Completion Notices are typically used where a planning permission has technically been implemented, but then left unfinished for months or years. Sometimes this is because the developer mothballs the project; sometimes because the property has changed hands; sometimes because the market has shifted.

Councils can issue a Completion Notice when they believe the planning permission is being kept alive without real intent to complete. It is not a punitive measure – it is a tidying-up mechanism to prevent open‑ended permissions remaining valid indefinitely.

What Does a Completion Notice Do?

The notice sets out a completion date, usually at least 12 months from the date it is served. If the work is finished by that deadline, the permission remains lawful. If not, any incomplete elements lose the benefit of that permission and future works would require a fresh application. Importantly, a Completion Notice does not affect work already lawfully completed – only the unfinished parts are at risk. This distinction matters for buyers inheriting part‑built extensions, conversions, shopfront works or redevelopment schemes.

How Do Completion Notices Affect Conveyancing?

If a property involves unfinished works or has an historic planning permission that was only partially implemented, a Completion Notice can materially affect value, development potential and mortgageability. Buyers may assume they can pick up where the previous owner left off… but a Completion Notice may limit what can still be lawfully completed without a new permission.

Lenders may also ask questions if a planning permission is close to expiry or if the remaining works are substantial. For developers purchasing stalled sites, understanding whether a Completion Notice has been issued, or could realistically be issued, is essential due diligence.

Will Completion Notices Show Up in Searches?

Completion Notices can appear in Local Authority searches when formally served, but they are not as common as enforcement notices. Sometimes the only evidence is in the planning history, which may reference a pending notice, consultation on a proposed notice or an intention to issue one. Because the effect of a Completion Notice is tied to the status of an existing planning permission, conveyancers should always check the planning timeline: When was the permission granted? Was it materially started? How much work was done? Does the council appear to consider the permission dormant?

What Should Buyers and Developers Look Out For?

Clients should be aware of any part‑built structures, groundworks or foundations that were installed solely to “keep a permission alive”. They should also understand that finishing the work may still require compliance with updated building regulations or new planning policies, even if the original permission is technically still in play. Where a Completion Notice has been served, buyers need to know the cut‑off date and whether the remaining works are realistically achievable within the timeframe. Where no notice has yet been served, but the project has been dormant for years, it’s sensible to advise that the council could tighten the timeline.

Completion Notices are a planning tool designed to bring clarity to long‑stalled developments. They don’t punish owners, and they don’t invalidate completed work – but they do remove the safety net of an old planning permission if the project isn’t finished by a specified date.

For conveyancers, the key is to spot early when a transaction involves part‑completed development, long‑dated permissions or dormant projects. A simple review of planning history and a discussion with the client can prevent surprises later and ensure they know exactly what they can – and cannot – lawfully complete after purchase.