Retrospective Planning Permission: What If You’ve Already Built?
You can apply for planning permission after work has started or finished. But approval is not automatic, and applying retrospectively is not always the right first step. Planning Portal’s retrospective permission guidance.
It is quite common for people to phone me surprised that the Council has contacted them telling that they have done something that requires planning permission. Perhaps you thought your extension was permitted development. Perhaps the finished building differs from the approved drawings. Or perhaps you got advice from someone down the pub that turned out to be not quite right!
Whatever brought you here, the useful question is what can be done about it.
At Fellpath Planning, we start by establishing what has happened, what permission was needed and which route offers a realistic solution. That assessment can prevent a rushed application from becoming another expensive problem.
Has the council already contacted you?
Read the correspondence carefully and identify every deadline. An informal invitation to apply and a formal enforcement notice require different responses.
Submitting an application does not, by itself, suspend an enforcement notice or extend its appeal deadline. An enforcement appeal must reach the Planning Inspectorate before the notice takes effect. Government guidance on enforcement appeals.
If you have received a letter or notice, start with our guide: Received a Planning Enforcement Letter or Notice? What Should You Do Next?.
What is retrospective planning permission?
A retrospective application asks the planning authority to approve development that has already taken place. It can concern building work or a change in how land or a building is used.
The legal route is commonly called a Section 73A application. If the council invites you to apply, that invitation does not promise approval: the application still needs to be assessed. Planning Portal’s explanation.
Treat the invitation as the beginning of a planning assessment. Ask what the council considers unauthorised, what concerns need addressing and what evidence it expects.
Should I apply immediately?
First establish whether an application is necessary and whether it has a reasonable prospect of success.
These are the questions we would work through:
What exactly has been built, or what use has started?
Does an existing permission or permitted development right cover it?
Could the development already be lawful?
Could the council support what exists?
Would changes resolve the concerns?
Has formal enforcement action begun?.
Check the decision notice, approved plans and conditions together. A permission for one scheme does not necessarily cover a larger building, a different position or a different use. The Planning Inspectorate identifies compliance with an existing permission and permitted development rights as matters that can establish that no breach occurred. Enforcement appeal guidance.
“The builder said it was fine” is useful background. It is not enough to settle the planning position.
Could a lawful development certificate be better?
A retrospective application seeks permission. A lawful development certificate establishes whether the specified development or use is already lawful for planning purposes.
An existing-development certificate may be appropriate where permission was unnecessary, the development complied with an existing permission, or the relevant enforcement period has expired and the legal requirements are met. It is decided on law and evidence, rather than the council’s opinion of the planning merits. Government guidance on lawful development certificates.
Dates and records can therefore be decisive. Photographs, invoices, tenancy documents, historic plans and witness evidence may help establish what happened and when. The evidence must address the particular building or use being claimed as lawful.
Does the four-year rule still apply?
The rules have recently changed but if your building or use has been in place for ten years or more then a lawful development certificate can definitely be relied upon. However there is many cases where you only need to show a use of development in place for four years too
Exceptions include previous enforcement action and deliberate concealment. Government guidance on enforcement time limits.
Do not rely on a building’s age alone. For example, an older outbuilding and its more recent use as separate accommodation raise different questions. We would investigate the history of each before advising on a certificate.
What are the chances of approval?
A credible assessment needs the site details. A general success percentage would tell you little about your own prospects.
Our review would consider the principle of the use, design, neighbours’ living conditions, access, drainage, flood risk, landscape, ecology and heritage, as relevant. We would then identify the strongest points, the principal objections and whether further evidence could change the assessment.
Applications must be determined in accordance with the development plan unless material considerations indicate otherwise. Existing construction does not remove that requirement. National Planning Policy Framework.
Does it matter that the work was unauthorised?
Yes. Under policy DM8 of the August 2026 National Planning Policy Framework, where evidence establishes that unauthorised development was intentional, that fact should carry substantial weight when considering permission. It does not create an automatic refusal, but it can materially affect the case. NPPF, policy DM8.
Keep an accurate account of the decisions made, advice received and circumstances in which the work occurred. Explain those circumstances honestly and support them with records where possible.
Could changes make the development acceptable?
Sometimes the most useful work is identifying a manageable change.
For example, imagine an extension with a window overlooking a neighbour’s private garden. We would investigate whether a different window arrangement could address the concern while retaining the room’s usefulness.
A business use might require a different assessment: could delivery arrangements, operating hours or the position of equipment reduce its effects without making the business impractical?
These are illustrative questions, not promises that a particular alteration will secure approval. A detailed assessment may show that the underlying location or use remains unacceptable.
This is where Fellpath’s experience in housebuilding and development matters comes to fruition. We consider the cost and practicality of possible changes alongside their planning benefits. An apparently simple compromise deserves scrutiny if it leaves you with a room you cannot use or a business you cannot operate.
What information will an application need?
Begin with accurate drawings showing what exists. Original design drawings are insufficient if the building was constructed differently.
A useful working file usually includes:
A location plan, measured drawings and current photographs.
Previous permissions, approved plans and relevant conditions.
A chronology of construction and any changes of use.
All council correspondence, including complete copies of notices.
A clear description of what you want to retain and any proposed alterations.
Depending on the issues, specialist evidence might also be needed—for example on daylight, noise, access, drainage or heritage.
We would identify the questions those reports need to answer before recommending expenditure. Commissioning a large bundle of reports without an agreed strategy can consume money without improving the case.
Where alterations are proposed, the submission should distinguish clearly between the existing development and the changes for which approval is sought.
Can applying affect my appeal options?
Yes. The sequence of an application and enforcement action matters.
A related retrospective application can restrict a later enforcement appeal on ground (a), which asks for planning permission. For notices issued on or after 25 April 2024, the restrictions can extend to notices issued within two years after the related application ceased to be under consideration. Other appeal grounds may still be available. Planning Inspectorate guidance.
A council can also decline to determine a retrospective application where an enforcement notice has already been issued. Government guidance on retrospective applications.
This is a reason to check the available routes before submitting. Your adviser should explain how the recommended approach fits with any live notice and preserves the options that matter to your case.
How much does retrospective planning permission cost?
The budget depends on the work needed to resolve the issue. A modest extension with accurate drawings presents a different task from a disputed commercial use requiring technical evidence.
Allow for the relevant council application fee, drawings, any necessary specialist reports and professional advice. Also consider the cost of alterations or restrictions that might be needed to achieve an acceptable outcome.
At Fellpath, our standard consultancy rate is £175 per hour. We explain the proposed scope and charging basis before instruction. An initial review can help establish whether further spending on an application is justified.
Read more about planning consultancy costs and comparing quotations.
Where Community Infrastructure Levy applies, retrospective permission is generally ineligible for reliefs and exemptions other than the minor-development exemption. Previously secured relief can also be lost. Check the liability before choosing the route. Government guidance on retrospective permission and CIL.
How long does it take?
The usual statutory decision periods are eight weeks for most non-major applications and 13 weeks for major applications, running from a valid application. Applications requiring Environmental Impact Assessment normally have a 16-week period. Longer periods can be agreed in writing. Government guidance on application timescales.
Your overall programme also needs to allow for gathering records, preparing drawings, obtaining reports and responding to issues raised during assessment. Council workloads and the availability of specialist input can affect progress.
Ask for a programme with clear stages: preparation, submission, anticipated decision and any subsequent work. Keep enforcement deadlines visible throughout it.
Our article How Long Does Planning Permission Really Take? explains why the statutory period and the full project timetable can differ.
What happens if permission is refused?
Review the reasons before deciding whether to appeal, pursue a revised proposal or remedy the breach. Any existing enforcement notice needs separate attention.
Refusal can be followed by enforcement requiring the development to be removed or the previous position restored. Do not assume there will always be another opportunity to apply. Planning Portal’s guidance.
The practical assessment should compare the strength of the case, the cost of continuing and the value of the outcome. Our guide to appealing, resubmitting or walking away explains that decision in more detail.
Does planning permission resolve everything?
Planning permission and building regulations approval are separate. Securing one does not establish compliance with the other. Government guidance on building regulations approval.
A wider review may also need to address listed building consent, access rights, boundaries, restrictive covenants or other permissions. Raise these with the appropriate specialist before treating the matter as resolved. A planning solution should fit the whole project.
Already built? Find out where you stand
Fellpath Planning advises homeowners, landowners and businesses in Cumbria and beyond. We bring experience from local government, housebuilding and private consultancy to the assessment.
Our first task is to identify the actual problem and a proportionate response. That might mean preparing an application, assembling evidence of lawfulness, investigating amendments or advising that further expenditure is unlikely to achieve what you want.
To help us understand your situation, send:
The property or site address.
Photographs and any available drawings.
A brief explanation of the work or use, including when it began.
Previous planning decisions and council correspondence.
Details of any deadline or formal notice.
Tell us what you are trying to achieve, too. Retaining a family room, keeping a business operating and resolving a problem before a property sale can call for different priorities.
Ask Fellpath to review your options before you commit to an application.
This article concerns the planning system in England. The appropriate route depends on the development, evidence and any notices already issued. It provides general information rather than advice on an individual case.
David Wright MRTPI is the founder of Fellpath Planning, with more than 17 years’ experience across local government, housebuilding and private planning consultancy.