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The 4 year rule is set to be thrown out on 25th April 2024. On this date, all development subject to the 4 year rule will become subject to the 10 year rule instead. The good news is that if your development is already in place on 24th April 2024, then you will still have the opportunity to make use of the 4 year rule. If this applies to you, we recommend that you contact us immediately for advice.


If you make a change to a property that requires planning permission, you’re supposed to apply for planning permission first. If you make the change without planning permission – either because you didn’t apply or because permission was refused – that’s unauthorised development and unlawful. This means the council is entitled to take enforcement action. In many cases, the outcome of enforcement action will be that you must return the site to its former condition.

You can find out more about the sorts of changes – or “developments” – that require planning permission by clicking the button below.

You can also find out more about enforcement action by clicking the button below. 

However, nearly all unauthorised development becomes lawful & immune from enforcement action after a set time period.

The set time periods are currently:

Building, engineering & other construction works4 years
Change of use of a building to a dwellinghouse4 years
Everything else, including most breaches of planning conditions and changes of use10 years

These time limits on enforcement action are established by law. You can find them at section 171B of the Town and Country Planning Act 1990. They are commonly referred to as the 4 and 10 year rules. 


1Without planning permission, you’ve constructed a granny annexe in your garden that’s occupied by a close friend or relative4 years
2There’s a condition attached to a previous planning permission granted on your commercial site that restricts your opening hours to “Monday – Saturday, closed on Sundays and bank holidays.” You’ve been opening on Sundays without having applied for the condition to be varied or removed10 years
3Without planning permission, you’ve converted an old office building to a house4 years
4Without planning permission, you’ve added an extension to your industrial warehouse to provide more warehousing space4 years
5Without planning permission, you’ve constructed a new house on your farmland10 years

A word of warning

The 4 and 10 year rules do not apply if: 

  • The development has been deliberately concealed or is a result of fraudulent conduct or
  • The development is demolition of a building located in a Conservation Area.

Furthermore, the time limits are only relevant to planning consent. There are no time limits on enforcement action in the case of development requiring listed building consent. This means enforcement action could be taken against development carried out without the necessary listed building consent indefinitely. Click the button below to find out more about listed building consent, including what it is, when it is required and how to find out if your property is listed.


Although the time limits are “automatic”, the burden of proof is firmly on the developer (or site owner) to prove that the minimum time period has been met. 

If your local council becomes aware of your development and it is not immediately obvious that it has been in place for 4 or 10 years, then they may proceed to take enforcement action. Some councils will invite you to attempt to regularise the development – either by way of a retrospective planning application or a lawful development certificate – first.

In order to prove to your local council that the time limit for taking enforcement action against your development has expired – and to receive their formal confirmation that no enforcement action can or will be taken against it – you must apply for a lawful development certificate.

If the council is satisfied – on the basis of the evidence you have supplied with your application –  that your development has passed the relevant time limit for taking enforcement action, then they must issue a lawful development certificate. This certificate will forever act as formal confirmation that the development is lawful and cannot, therefore, be enforced against. 

When you submit an application for a lawful development certificate, your evidence should be varied and robust. It can include dated photographs, sworn affidavits, invoices and bills. If your local council refuses to issue a lawful development certificate, you’re entitled to reapply with more evidence.

Click the button below to find out more about lawful development certificates.


If your local council is aware…

If your local council is already aware of the unauthorised development then you may wish to consider applying for retrospective planning consent. Your planning application will be considered in the same way as any other application, meaning there is always a risk planning permission could be refused.

Click the button below to find out more about applying for retrospective consent.

If your local council is unaware…

If your local council is not aware of the unauthorised development, you may wish to wait for the 4 or 10 year period – as applicable – to expire. You must ensure you do not attempt to conceal the development. You should also start to gather evidence of its existence for a future application. There is always a risk your council will become aware of the development before you get there. If they do, they are likely to pursue enforcement action.

As of November 2023, the 4 year rule is on its way out. All development currently subject to the 4 year time limit will become subject to the 10 year limit instead. This means if your development has not yet been in place for 4 years, there is a significant risk you will no longer be able to take advantage of this rule.

If your local council has taken enforcement action…

If your local council issues an enforcement notice, you have the right to appeal this. An appeal must be submitted promptly and within the deadline that appears on the notice. There are multiple grounds of appeal, including that planning permission should be granted for the unauthorised development. If you fail to appeal or your appeal is dismissed, you must comply with the requirements of the notice. The requirements will usually include returning the site to its former condition. Failure to comply can result in criminal prosecution and an unlimited fine.

Click the button below to find out more about dealing with enforcement action, including the deadlines to appeal.


If your development has been in place for 4 or 10 years (as applicable) and your local council has opened an enforcement case but has not yet issued an enforcement notice, you should request that they postpone formal enforcement action whilst you apply for a lawful development certificate.

Most local councils are willing to await the outcome of an application for a lawful development certificate before taking formal enforcement action. However, if your application for a lawful development certificate is refused, it’s likely the council will issue an enforcement notice soon after. 

Enforcement notices are serious so you must deal with them promptly.

If you’ve already received an enforcement notice, you must either comply with it or appeal against it. The ground of appeal relevant to you will be ground (d). Ground (d) is that the time limit for taking enforcement action – 4 or 10 years – has passed. As long as your evidence is robust, you will stand a very good chance of winning the appeal. Depending on the specifics of your case, there may also be additional grounds of appeal. 

Click the button below to find out more about the different grounds on which you can appeal an enforcement notice. You can appeal on as many or as few grounds as you like.

Bear in mind that if you fail to either appeal or comply with the requirements* of an enforcement notice before the date it takes effect, you could face criminal prosecution. If found guilty, you could be issued an unlimited fine. 

*In most enforcement cases, the requirement will be to either remove or cease the unauthorised development and return the site to its former condition.

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