Retrospective planning applications and how to respond

A retrospective planning application asks the council to grant permission for something that has already been built or already changed use. It is a normal application with a statutory basis in section 73A of the Town and Country Planning Act 1990, it is decided on the same planning merits as any other, and the fact that the works exist is neither a point in the applicant's favour nor a reason to refuse. That last point is the one most neighbours find hardest to accept, and understanding why it holds is what makes an objection effective rather than merely angry.

Why the route exists

Carrying out development without permission is not a criminal offence in itself. Planning enforcement is about putting the land back into an acceptable state, so the system needs a way of regularising works that turn out to be acceptable and a separate way of removing works that are not.

Section 73A covers three situations. Development carried out with no permission at all. Development carried out in breach of a condition on a permission that was granted. And development carried out after a time limit for implementation had already expired. Permission can be granted so as to take effect from the date the development was carried out, which regularises the period of breach as well as the future.

People arrive at this route by several paths. Some build beyond what they thought was permitted development. Some discover a discrepancy when they come to sell. Some are invited to apply by an enforcement officer who thinks the works are probably acceptable and would rather not serve a notice. And a few build deliberately and take their chances, which is the category that generates most of the anger and the smallest proportion of the applications.

What the authority has to leave out of account

Three things carry no weight.

That the applicant did not apply first. The council decides whether the development is acceptable in planning terms, not whether the applicant behaved well. Moral arguments about dishonesty, however justified, get no traction in a planning report.

The cost of removal. An objector who argues that the applicant should be made to pay for their mistake, and an applicant who argues that demolition would be ruinous, are both asking the officer to consider something outside the planning merits.

Loss of property value. It is not a material planning consideration, whether raised by a neighbour or an applicant.

What does carry weight is everything that would have carried weight on a fresh application: the development plan, the effect on residential amenity, on highway safety, on heritage assets, on trees, on drainage, and on the character of the area.

Objecting when the work is already done

The practical advantage for an objector is that the thing being assessed is visible. Use it.

• Photograph the development from the affected windows and from the street, with dates.
• Describe the effect you experience, in specific terms: which room, at what time of day, what was visible before.
• Compare what was built with what the application drawings show, and say where they differ.
• Address the planning tests by name, using the wording of the local plan policies on amenity, design and whatever else is engaged.

Avoid arguing that permission should be refused because the applicant proceeded without it. Argue that the development as built causes harm the policies identify, and that the harm cannot be conditioned away. Our note on objecting to a retrospective planning application goes into the drafting in more detail.

Comments are usually invited for 21 days. If the drawings are amended during determination, the authority may or may not consult again, and the tests it applies are set out in our note on amended plans after you object.

Measuring what was actually built

This is where objections succeed or fail, because applications for existing development are drawn from measurement rather than from design intent, and the measurement is sometimes generous to the applicant.

Check three things against the submitted drawings:

1. Height, including ridge and eaves, measured from the original ground level rather than from a raised patio or new hard standing.
2. Depth of projection beyond the original rear wall, and whether the drawing shows the original wall line correctly.
3. Ground coverage, and whether outbuildings and hard surfacing already present are shown.

Where you think a dimension is wrong, say what you think it is and how you arrived at the figure. A neighbour who says the extension is roughly a metre deeper than the drawing shows, with a photograph taken against a fence panel of known width, gives the officer something to check on the site visit. A neighbour who says the drawings are lies does not.

Officers do measure on site when a discrepancy is alleged specifically. The mechanism of the application itself, including the effect on time limits and immunity, is set out in our note on retrospective applications under section 73A.

Conditions on a retrospective permission

Conditions still have to meet the usual tests: necessary, relevant to planning, relevant to the development, enforceable, precise and reasonable in all other respects. Applied to existing development, they typically do one of four things.

Where an officer recommends approval, a well drafted objection often shifts the outcome from an unconditional permission to one that requires an alteration. That is a real result, and it is more achievable than refusal in most cases.

If it is refused

Refusal does not remove the development. It leaves the works unauthorised, and the council then decides separately whether to take enforcement action, which is discretionary and has to be expedient in planning terms.

The applicant can appeal a refusal in the usual way. Section 70C of the 1990 Act also allows an authority to decline to determine a retrospective application where an enforcement notice has already been issued for the same matters, so the sequence in which things happen affects what routes remain open.

There is a further trap for applicants. Reliefs and exemptions from the Community Infrastructure Levy generally have to be claimed before development starts, so a scheme regularised after the event will usually have lost them. Anyone considering building first and applying later should price that in.

The enforcement route running alongside

A complaint to planning enforcement and a retrospective application can be live at the same time, and they are separate processes with separate timescales.

Enforcement is discretionary. The council will consider whether the breach causes harm that justifies action, and it can accept the works, negotiate a change, or serve a notice. Time limits matter: immunity from enforcement arrives after a period of continuous breach, and the Levelling-up and Regeneration Act 2023 aligned the shorter four year period for building works and for change of use to a single dwellinghouse with the longer period in England. Commencement and transitional arrangements matter to individual cases, so ask the council which period it says applies to the works you are complaining about.

Keep both routes running. Make your representations on the application, and separately give the enforcement team your dated evidence of when the works were carried out, because that evidence is what decides the immunity question if the application is refused.

If you are on the applicant side and need the supporting documents for a section 73A application, you can browse the 66 PlanScope report types to see what the council is likely to expect.

This is general guidance, not legal advice, so check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.