When silence from the council counts as prior approval
If the council does not notify you within the period the GPDO sets, you may build what you described. Silence does not cure a scheme that was never permitted development.
If the council does not notify you of its decision on a prior approval application within the period the General Permitted Development Order sets, you may proceed with the development as described in your application. That is deemed prior approval, and it is written into the Order rather than being a courtesy or a convention.
The periods differ by Part. Most of the change of use classes in Part 3 run to 56 days. The larger householder extension procedure in Part 1 runs to 42 days. Agricultural determinations under Part 6 run to 28 days. Getting the wrong number, or the wrong start date, is how people build unlawfully while believing they are covered.
The determination periods that actually apply
Check the Part your class sits in rather than relying on a general rule.
| Regime | Period |
|---|---|
| Part 1 Class A, larger householder extension | 42 days |
| Part 3 changes of use, including Class MA and Class Q | 56 days |
| Part 6 agricultural determinations | 28 days |
| Part 16 electronic communications apparatus | 56 days |
| Part 20 new dwellings and upward extensions | 56 days |
Two of these behave differently from the others. The Part 6 procedure asks first whether prior approval is required at all, so a council that says nothing for 28 days has effectively said it is not required. The Part 1 larger extension procedure is triggered only where a neighbour objects, and the period runs whether or not anyone does.
Where a class requires prior approval for several matters, silence covers all of them. The council cannot approve siting by silence and then refuse external appearance afterwards.
How the period is counted
The clock starts on the date the local planning authority receives the application, not the date you post it and not the date the authority validates it. That distinction is the source of most disputes.
"Received" means received with everything the Order requires: the description of the proposed development, the plans, the site address, the contact details, the fee and any class-specific information such as a flood risk assessment or a transport statement. Where an item is missing, the authority can argue the application was never properly made and that the period never started.
So the practical discipline is to submit a complete application, pay the fee at the point of submission, and keep the acknowledgement. If you submit through the national planning portal, the submission receipt gives you a timestamp the authority cannot easily dispute. If you submit by email, ask for written acknowledgement of receipt on the day.
The authority has to notify you within the period. A decision signed on day 55 and posted so that it reaches you on day 58 has been litigated more than once, and the safer assumption is that a decision you have not received by the final day is a decision that has not been given. Take advice before acting on that assumption rather than relying on it blindly.
What you may build when the council is silent
Exactly what you described. Deemed prior approval attaches to the development set out in the application, with the drawings you submitted, and it carries the conditions written into the class itself.
Three consequences follow, and they catch people in sequence. The submitted drawings become the permission, so a change on site is a departure. The class conditions still bind, including any requirement to complete within a stated period or to carry out the development in accordance with the details provided. And any limitation in the class, whether that is a floorspace cap, a height limit, an eligibility date or a designation exclusion, applies exactly as it would have done.
That last point is the one worth repeating. Deemed approval does not cure a scheme that was never permitted development in the first place. If the building did not meet the qualifying use on the relevant date, or the site is on land where the class does not apply, silence from the council changes nothing. The development is unauthorised and remains enforceable.
Draw your submitted plans to a standard you would be content to build from, because you will be building from them. Vague drawings submitted in the hope of resolving detail later are a liability once the period expires.
Why the submitted details become binding
Prior approval is not planning permission. It is the mechanism by which the Order allows the authority to control specified matters within development that is already permitted. When the period expires without a decision, the control falls away, but the permission is still the class permission, granted for the development described.
That is why a builder's decision to move a window, change a cladding material or shift a footprint by a metre matters more here than it would on a full permission, where a non-material amendment route exists. There is no equivalent route for prior approval. The options are to submit a fresh application or to apply for planning permission for the difference.
Where the change is significant, take the fresh application. It costs a fee and a determination period, and it is considerably less expensive than an enforcement notice served two years later.
Extensions of time and written agreement
Most of the prior approval provisions allow the period to be extended by written agreement between the applicant and the authority. Councils ask for this routinely when they are short-staffed or when a consultee has been slow.
Agreeing an extension is often sensible. A refusal you can appeal is more useful than a deemed approval you cannot rely on, particularly where the authority has raised a substantive issue you could resolve with an amended drawing.
But agree it properly. The agreement must be in writing, it must state the new date, and it should be made before the original period expires. An email exchange after the deadline does not revive a period that has already run.
Evidence to keep for a future sale
A deemed approval leaves no decision notice, which is a problem when a purchaser's solicitor asks for one. Assemble the file at the time and keep it.
- The submitted application, drawings and supporting documents as submitted.
- Proof of the date of receipt: the portal receipt, the fee payment record, or a written acknowledgement.
- Any correspondence with the authority during the period.
- Evidence that nothing was received from the authority before the expiry date.
- Photographs and a surveyor's record showing that what was built matches what was submitted.
Where the transaction or the finance depends on it, apply for a certificate of lawfulness for an existing use or development under section 191 of the Town and Country Planning Act 1990 once the works are complete. That certificate is the only formal way to confirm that works are lawful, and it converts an evidential argument into a document.
The risks of relying on silence
The recurring failures are worth naming plainly. An incomplete application that never started the clock. A class limit that was never met, such as the qualifying use or vacancy conditions in Part 3. A site subject to an Article 4 direction removing the right. A development begun before the period expired, which is itself a breach. And a set of drawings too vague to define what was approved.
None of these is a reason to avoid the prior approval route. It remains faster and more certain than a full application for schemes that really do fit a class, whether that is a Class A rear extension, adding a storey under Class AA or extending a shop under Part 7. The route works when the application is complete, the drawings are precise and the class limits are met before you submit.
Set out the class analysis clearly in the supporting statement, in the same way you would structure a Planning Statement for a full application, so the officer can see the qualifying conditions are satisfied.
Enter your postcode on PlanScope to see which supporting documents your prior approval application is likely to need.
This is general guidance rather than legal advice. Check the position with your local planning authority or a qualified professional before relying on it, and remember that a lawful development certificate is the only formal way to confirm that works are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Is the prior approval period always 56 days?
No. Most change of use classes in Part 3 run to 56 days, as do Part 16 telecoms and Part 20. The larger householder extension procedure in Part 1 runs to 42 days, and agricultural determinations under Part 6 run to 28 days. Check the Part your class sits in rather than assuming a single figure.
When does the clock start?
On the date the local planning authority receives a complete application, including the plans, the required information and the fee. It is not the date you post it or the date the authority validates it. Where an item is missing the authority can argue the application was never properly made and that the period never began.
What if the decision is posted in time but arrives late?
The Order requires the authority to notify the applicant within the period. A decision signed on day 55 and received on day 58 has been litigated more than once. The safer working assumption is that a decision you have not received by the final day has not been given, but take advice before acting on it.
Can I change the design after a deemed approval?
Not without a fresh application. Deemed approval attaches to the development described in your submitted drawings, and there is no non-material amendment route for prior approval as there is for planning permission. A change on site is a departure, so either resubmit or apply for planning permission for the difference.
How do I prove a deemed approval to a buyer?
Keep the submitted application and drawings, proof of the receipt date, the fee record, any correspondence and evidence that nothing was received before expiry. Where the sale or the finance depends on it, apply for a certificate of lawfulness under section 191 once the works are complete, which turns the evidence into a document.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.