The 10-year rule covers any breach of use of land or buildings (excluding dwellings) which has not been challenged by enforcement action for at least ten years. A "dwelling" is deemed by planning law to be a class C3 in terms of use and is covered by the 4-year rule.
Retrospective Planning Permission
The 10-year rule and the 4-year rule are rules that can provide retrospective planning permission through a Certificate of Lawfulness once a project has been in use for years. Building regulations approval does not share these rules and has no rules allowing exceptions after any period of time.
Extension of Time Period
The government plans to abolish the 4-year rule and extend the period to 10 years. This would apply the 10-year rule to all breaches of planning control. The press recently reported on a case where the council granted a lawful development certificate for a dwelling hidden in woodland that would have previously fallen under the 4-year rule.
Enforcement and Immunity
The 10-year rule refers to a legal loophole in UK planning regulation. If no enforcement is taken within four years of a project’s completion, it is granted immunity from enforcement action.
The 10-year rule covers any breach of use of land or buildings (excluding homes) that has not been challenged by enforcement action for at least ten years. A "home" is deemed by planning law to be a class C3 dwelling and is covered by the 4-year rule.
Use as a Dwelling
The 4-year rule applies to using any building or part of a building as a dwelling. For example, if a pub was converted to a house in 2019 without planning permission, it could become lawful in 2023 by the 4-year rule. The 10-year rule covers any breach of land or building use, excluding dwellings, not challenged by enforcement action for ten years.