The 4-year rule in planning: does it still apply?
The 4-year rule used to be one of the most useful parts of the planning enforcement system.
In simple terms, some unauthorised building works, and some unauthorised changes of use to a single dwellinghouse, could become lawful if they had existed for four years without enforcement action being taken. The development might never have had planning permission, but it could become lawful through the passage of time.
This was often important where a planning problem was discovered during a sale, remortgage or enforcement investigation. An extension might have been built years earlier by a previous owner. A building might have been used as a separate dwelling for a long period. The planning records might be unclear. In those circumstances, a Lawful Development Certificate could provide the formal confirmation needed.
However, the law changed on 25 April 2024. The 4-year rule has not vanished altogether, but it no longer applies in the same way to all cases.
The 4-year rule and the 10-year rule
The 4-year rule used to apply to two important types of planning breach: operational development and the change of use of a building to a single dwellinghouse.
Operational development means building works, engineering works or other physical operations. An unauthorised extension, outbuilding, roof alteration or new building could fall into this category.
The change of use of a building to a single dwellinghouse means, for example, a building being used as a separate house or flat without planning permission.
Before 25 April 2024, these types of breach could become immune from enforcement action after four years. Other breaches, including most changes of use and breaches of planning conditions, were subject to a 10-year rule.
That has now changed. For newer cases, the relevant period is 10 years. This means that an unauthorised extension, outbuilding or separate dwelling will not normally become lawful after four years if it was substantially completed, or first used as a separate dwelling, on or after 25 April 2024.
The old 4-year rule can still apply where the building works were substantially completed before 25 April 2024, or where the use as a single dwellinghouse began before that date. For those older cases, it may still be possible to apply for a Lawful Development Certificate confirming that the development is immune from enforcement action.
The important point is that dates now matter. It is not enough to say that an extension is ‘old’ or that a flat has been there ‘for years’. The question is when the works were substantially completed, or when the relevant use began. That date may decide whether the old 4-year rule is still available, or whether the owner is now looking at a 10-year period instead.
We have dealt with many cases where this issue has been crucial, including an application for a Certificate of Lawfulness under the 4-year rule for a new dwelling and an application for a Certificate of Lawfulness for a house established use under the four-year rule.
A Lawful Development Certificate is about evidence, not planning merits
A Lawful Development Certificate is different from a planning application. With a planning application, the council asks whether the development is acceptable in planning terms. It considers design, neighbour impact, parking, policy and all the usual planning issues.
With a Lawful Development Certificate, the question is narrower. The council is not deciding whether it likes the development. It is deciding whether it is already lawful. In an immunity case, that usually means deciding whether the development has existed, or the use has continued, for long enough to be immune from enforcement action.
This is why evidence is so important. The council will not simply take the owner’s word for it. The applicant has to show, on the balance of probability, that the relevant facts are true. Useful evidence may include dated photographs, builder’s invoices, building control records, council tax records, utility bills, tenancy agreements, floor plans and statutory declarations from people with direct knowledge of the property.
Many cases are less straightforward than they first appear. The council may accept that a building exists now, but dispute when it was substantially completed. It may accept that somebody has lived in a building, but dispute whether the use was genuinely as a separate dwellinghouse. It may accept that a property has been divided into flats, but dispute whether that use was continuous throughout the relevant period.
That is why these applications need to be prepared carefully. The evidence does not need to be perfect, but it does need to be coherent. A successful application usually tells a clear story, supported by documents from different sources.
Examples of Lawful Development Certificate cases
Lawful Development Certificate cases come in many forms.
Sometimes they involve a building that has been used as a separate dwelling for many years. Sometimes they involve a house that has been divided into flats. Sometimes they involve an outbuilding that has gradually taken on a more independent residential use.
We have obtained certificates in a range of cases, including a Certificate of Lawfulness for the use of a building as two separate flats, a Certificate of Lawfulness for the use of an outbuilding as a separate dwelling, a Certificate of Lawfulness for a conservatory extension and outbuilding as a separate dwelling and an application for a Certificate of Lawfulness for the use of a building as 14 self-contained flats.
The common theme in these cases is evidence. The planning merits may be interesting, but they are not usually the main issue. The main issue is whether the applicant can prove, clearly and consistently, that the relevant use or development has become lawful.
Why not just leave it alone?
Some owners take the view that, if the council has not complained, it is better to do nothing. In some cases, that may be a perfectly rational decision. Not every historic planning problem needs to be regularised immediately.
However, there are situations where the issue cannot easily be ignored. A buyer’s solicitor may raise it during a sale. A lender may ask for proof that a dwelling is lawful. A neighbour may complain. The council may open an enforcement investigation. A landlord may need certainty before letting or refinancing a property.
In those situations, a Lawful Development Certificate can be very valuable. It gives formal confirmation that the development is lawful for planning purposes. It can help resolve conveyancing problems, reduce enforcement risk and give owners confidence about the status of their property.
A certificate does not override other legal regimes. It does not, for example, remove the need to comply with building regulations, licensing rules or listed building control. Even so, in planning terms, it can be extremely important.
What if the 4-year rule does not apply?
If the 4-year rule does not apply, that does not necessarily mean the position is hopeless.
In some cases, the development may be permitted development. In others, a retrospective planning application may be possible. Sometimes the best strategy is to negotiate with the council, amend the development or apply for planning permission rather than trying to prove immunity.
If the council has already served an enforcement notice, it may be possible to appeal. The right approach will depend on the facts, the evidence, the planning harm alleged by the council and the available grounds of appeal.
This is why it is important not to jump to conclusions. The fact that a development is not immune from enforcement action does not automatically mean it must be removed. It simply means that another route may be needed.
How Just Planning can help
Just Planning regularly advises homeowners, landlords and developers on Lawful Development Certificates, retrospective planning applications and planning enforcement cases.
We can review the planning history, photographs, building control records, council tax documents, tenancy evidence and any correspondence from the council. We can then advise whether the 4-year rule may still apply, whether the 10-year rule is now relevant or whether another route would be more sensible.
Where there is a reasonable case, we can prepare and submit the Lawful Development Certificate application, organise the evidence and explain clearly why the legal test is met. If the application is refused, we can advise on the prospects of appeal.
The 4-year rule has changed, but it has not vanished completely. The important thing is to understand which time limit applies, what needs to be proved and whether the evidence is strong enough.
If you are dealing with an old extension, an unauthorised dwelling, a divided building or an enforcement investigation, contact Just Planning for clear, fixed-fee advice on your options.
