When you need it, why councils grant it, and the legal framework that controls the answer.
Yes, you can get retrospective planning permission. Section 73A of the Town and Country Planning Act 1990 allows local planning authorities to grant consent for development that has already been built or for a change of use that has already taken place. The council must assess the application as if the work had not yet been carried out — on its planning merits. In our experience, around 70% of these applications are approved, a further 10% are approved with minor modifications, and 20% are refused.
Retrospective planning permission is the formal route for regularising development that has been carried out without the consent it required. It is not a separate kind of permission — it is the same Section 70 / Section 73A application process, with the only difference being the timing. The council looks at exactly the same policies, the same NPPF and the same Local Plan, and applies the same tests. The only advantage to the applicant is that there is no need to model what the finished development might look like, because it already exists.
Retrospective planning permission is required when development work or a change of use has been carried out without prior approval from your local planning authority (LPA). The starting point is the legal definition of "development" in section 55 of the Town and Country Planning Act 1990:
"Development means the carrying out of building, engineering, mining or other operations in, on, over or under land, or the making of any material change in the use of any buildings or other land."
For the purposes of the Act, "building operations" includes demolition, rebuilding, structural alterations or additions to buildings, and other operations normally undertaken by a builder. Material changes of use are not defined in statute and are determined as a matter of fact and degree by the LPA in each case.
The definition of "building" is not laid down in statute. The courts apply three tests:
Works that fall outside the definition of "development" do not need permission at all. These include works to the interior of a building (though listed building consent may still be required) and works that do not materially affect the external appearance of the building.
Before any project, three questions need an answer:
The mistake most homeowners make is stopping after step 2 without checking whether their property has any conditions or Article 4 directions removing the usual permitted development rights. Many newer detached houses, properties in conservation areas, and houses on conditioned estates do not have the freedoms that the GPDO ostensibly grants.
If you have built without consent and the council finds out, the risks of not engaging are real:
Yes — you can get retrospective planning permission, and most of the time you will. The rules are exactly the same as for a normal application; the difference is that the work is already in front of the case officer when they make their decision. A properly prepared application, framed against the right local plan policies, has a strong chance of success.
Yes. Section 73A of the Town and Country Planning Act 1990 explicitly authorises local planning authorities to grant permission for development that has already been carried out. It is a formal route built into the planning system.
The application fee is the same as for a normal planning application of the equivalent type. Householder applications carry the standard council fee (paid directly by you to the council). RPE charges a fixed fee of £450 + VAT for householder cases and £695 + VAT for everything else.
It is technically possible but most buyers' solicitors will require either a Lawful Development Certificate (if the works are old enough) or a successful retrospective planning permission before exchange. Mortgage lenders often refuse to lend against unauthorised structures.
If the development is older than the section 171B time limit, you may already be immune from enforcement and can apply for a Lawful Development Certificate. If it is newer, ignoring the issue invites an Enforcement Notice — and once a notice is in force, the appeal options narrow significantly.
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