Built without permission in London? Find out where you stand, £220
A written assessment of work already done: is it permitted development, is it too old for the council to act, how likely is a retrospective application to succeed, and what happens if you leave it.
£220 fixed fee, no VAT to add
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The short answer
Before you spend on an application, find out whether you need one. Our retrospective assessment is a written report on work you have already built or bought: whether it was permitted development all along, whether the time limit for enforcement has passed, how strong a retrospective application would be, and what doing nothing risks. The fee is £220, no VAT to add.
Retrospective planning assessment
from £220
- Fixed fee
- £220
- VAT
- None to add
- Was it permitted development after all? Checked against what was built and the rules in force at the time
- Is it too old for the council to act on? The completion date tested against the enforcement time limits
- How strong a retrospective application would be, against the council’s own policies and your neighbours’ windows
- Whether a lawful development certificate is a better route than an application
- What happens if you do nothing, in plain terms, for a sale, a remortgage or a complaint
- A fee credited in full against our retrospective application for the same property
£220. A starting fee: we confirm one fixed figure after checking your address. The council’s own fee, where there is one, is paid to the council.
Get my fixed feeHow the assessment runs
Tell us what stands
The address, what was built, when it was finished and any letter from the council. Photos help.
We check the record
The planning history, any approved drawings, conservation or Article 4 limits, and whether the work matches what was permitted.
We test the four answers
Permitted development, immune by time, a retrospective application, or a lawful development certificate.
Your written assessment
The likely outcome of each, our recommendation and the risks of waiting, in a report you keep.
Decide what next
Stop there, or move on to the application with the assessment fee taken off.
Do you need a retrospective application at all?
Not always. Three things can mean you do not: the work was permitted development when you built it, it was finished long enough ago that the council can no longer act, or it matches an old permission. Each is checked against facts, and each gives you a different piece of paper.
If the work was lawful by time, a lawful development certificate can prove it. Under section 191, work is lawful when no enforcement action may be taken against it, and a certificate in force makes that lawfulness conclusive.
How long can the council act?
For building work in England, section 171B now gives the council ten years from substantial completion, a change made from 25 April 2024. The Planning Practice Guidance keeps the older four-year limit for work completed before that date.
So the first fact we pin down is the completion date, and how you can show it. A builder’s invoice, dated photos and council tax records can all help, and we tell you in the report which ones carry weight.
What if you do nothing?
Often nothing happens for years, until a buyer’s solicitor asks for the paperwork or a neighbour complains. If the council writes, the first letter may be a planning contravention notice, and failing to complete and return it within 21 days is an offence, according to the Planning Practice Guidance.
There is one more reason not to drift. The guidance says a person who has built without permission has only one opportunity to get it after the event, and under section 70C a council may decline to decide an application once an enforcement notice has been issued. Choosing the route while the choice is still yours is the point of this report.
What our paid assessment gives you that a free one does not
A free chat will often tell you the work probably needs permission, then offer a quote for an application. That is a sensible first step, but it is not an answer to the questions you started with.
Our assessment is a written report you can show a lender, buyer or solicitor, written by a chartered architectural technologist (MCIAT). It tests all the ways out, including the ones that need no application at all, and it looks at your neighbours, the policies and the planning history, not only the headline breach. If you go on, we can draw the work as built or the change that would win consent, and the fee is credited in full against our retrospective application.
- It can say “you need nothing more”, and it is written to be believed if it does
- It weighs doing nothing as honestly as it weighs applying
- Cost and process of the application itself are in our retrospective application page
Check the position before the council does
Whether the work needed permission, and how long the council can act on it, depends on what was built and when it was finished.
Retrospective planning by the numbers
10 years
The enforcement time limit for building work in England, counted from substantial completion (section 171B(1)(a)).
Source: Town and Country Planning Act 1990, section 171B (legislation.gov.uk)
25 April 2024
The date the ten-year limit began to apply, in place of four years, for work completed on or after it.
Source: Town and Country Planning Act 1990, section 171B (legislation.gov.uk)
4 years
The limit that continues to apply to building work substantially completed before 25 April 2024.
Source: Planning Practice Guidance: ensuring effective enforcement (GOV.UK)
21 days
The time to complete and return a planning contravention notice; failing to is an offence.
Source: Planning Practice Guidance: ensuring effective enforcement (GOV.UK)
1 chance
The guidance says a person who has built without permission has only one opportunity to obtain it after the event.
Source: Planning Practice Guidance: ensuring effective enforcement (GOV.UK)
£548
The council fee for a householder application on one house from 1 April 2026, and a retrospective one pays it too.
Source: Planning fees: annual indexation from 1 April 2026 (GOV.UK)
Questions about work built without permission
How do I find out whether I needed permission?
Compare what was built with the permitted development rules that applied when it was built, and with any approval on the property. That comparison is the first part of the assessment.
What if the work is more than ten years old?
Then the council may be out of time, but the date that counts is substantial completion, and the rule differs for older work. We test the date, and a lawful development certificate can record the result.
Source: Town and Country Planning Act 1990, section 171B (legislation.gov.uk)
Does the fee come off the application if I go ahead?
Yes. It is credited in full against our retrospective application for the same property.
My solicitor has found something unauthorised while I sell. What do I do?
Send us what the solicitor has said. The assessment tells you whether it is a real problem and which paper fixes it, so you can answer the buyer with a clear route. Messages before 3pm get a reply the same working day.
Can you guarantee a retrospective application will succeed?
No, and no honest adviser can. The assessment states how strong the case looks and why.
Know your position before you pay for an application
Tell us what was built and when. We reply with what we need and start the assessment for £220, credited if you go on with us.