“It’s permitted development, but you still need prior approval before you start.” Said out loud, that sentence sounds like a contradiction — either you need the council’s involvement or you don’t. In fact both halves are true at once, and untangling why is one of the more genuinely useful things a homeowner can understand before committing to a larger project.
This article focuses on the prior approval system in England.
Three different situations, often lumped together
It helps to separate what are actually three distinct positions:
Full planning permission. The council assesses your specific proposal on its planning merits and decides whether to grant or refuse it. This is what most people picture when they think “planning application.”
Permitted development, no further process. The right is granted nationally in advance. Provided the work meets the specific limits and conditions attached to it, no separate planning application or prior approval process is required.
Permitted development, subject to prior approval. The right is still granted nationally in advance, in the sense that no conventional planning application is needed and the council isn’t assessing the whole scheme on its planning merits. But before work can start, a specific, limited set of matters has to go through a formal council process. What the council is allowed to consider depends on the particular permitted development class.
The confusion nearly always comes from treating the second and third as the same thing. They’re not. Both can avoid a full planning application. Only one lets you proceed without first completing a council process.
Where this shows up for homeowners
The clearest domestic example, and the one many homeowners encounter, is the larger home extension scheme — sometimes called the neighbour consultation scheme.
It applies to single-storey rear extensions that exceed the ordinary permitted development depth limits but stay within the larger limits: more than 4 metres and up to 8 metres for a detached house, or more than 3 metres and up to 6 metres for any other house, in England.
Other permitted development rights also use prior approval. For homeowners, one important example is the Class AA route for adding additional storeys to certain dwellinghouses. Elsewhere in the GPDO, prior approval also appears in some change-of-use and other development rights, with completely different matters for the council to assess.
So “prior approval” isn’t one universal test. It is a mechanism used by different permitted development rights for different specified issues.
The government’s explanation of the neighbour consultation scheme is available through its permitted-development guidance. GOV.UK guidance on when permission is required
Walking through the larger rear extension process
Where the ordinary limits stop. For a single-storey rear extension, the standard permitted development depth is up to 4 metres for a detached house and up to 3 metres for any other house, measured from the rear wall of the original dwellinghouse. Staying within those dimensions does not trigger the larger home extension neighbour consultation process, although all the other relevant Class A limits and conditions still have to be satisfied.
Where the larger route begins. Wanting to build beyond that standard depth, but still within the larger 8-metre or 6-metre limits, triggers the prior approval process. This isn’t an upgrade you get automatically — the required information has to be submitted to the council before work starts.
The application includes the extension’s depth, maximum height and eaves height, a plan showing the proposed development, the addresses of adjoining premises and the developer’s contact details. The council can also ask for further information where reasonably necessary to determine the application.
As of 1 April 2026, the statutory England fee for a householder prior approval application covering a larger rear extension under Part 1 Class A is £249. Fees are indexed, so that figure should be checked again if applying in a later year.
The council first checks whether the scheme actually qualifies. Prior approval is not a way around the underlying permitted development rules. The council can refuse the application if the proposal does not comply with the relevant Class A conditions, limitations or restrictions, or if insufficient information has been provided to establish that it does.
That point matters. A lack of neighbour objections cannot rescue an extension that is too high, too deep, on land where the larger right is unavailable, or otherwise outside the permitted development rules.
Notification. If the application proceeds, the council must notify the owners or occupiers of adjoining premises. The notice describes the extension, including how far it projects beyond the original rear wall, its maximum height and its eaves height.
Neighbours must be given at least 21 days from the date of the notice to make representations.
If no objections arrive. If no adjoining owner or occupier objects during the consultation period, prior approval of the impact on neighbouring amenity is not required. Provided the proposal otherwise qualifies as permitted development, the council should notify the developer accordingly.
The council does not then embark on an ordinary planning merits assessment simply because the extension is large.
If objections do arrive. If any adjoining owner or occupier objects, prior approval becomes required specifically in relation to the impact of the proposed development on the amenity of adjoining premises.
The council must take the representations into account and assess the amenity of all adjoining premises, not merely the property whose owner submitted the objection. It may request further information from the developer where reasonably necessary to make that assessment.
The 42-day rule. This is an unusual and important feature of the larger home extension process.
The development must not begin until one of three things has happened:
- the council confirms in writing that prior approval is not required;
- the council gives prior approval; or
- 42 days expire after the required information was received by the council without the council notifying the developer whether prior approval is given or refused.
If that third outcome occurs, the GPDO itself allows the development to proceed in accordance with the submitted details, subject to the other permitted development conditions still being satisfied. It is not necessary first to win a non-determination appeal simply because the council has missed the 42-day period.
Government’s current Planning Inspectorate guidance likewise identifies 42 days as the determination period for a valid larger single-storey rear extension prior approval application.
In practice, don’t guess when those 42 days started. Keep the council’s acknowledgement and application records so the receipt and expiry dates are clear.
Only then, construction. Work should not begin before one of those statutory outcomes has occurred. Starting early can mean the development does not comply with the conditions of the permitted development right, even if the physical extension would otherwise fall within the dimensions.
And there is one final administrative step that is easily overlooked: after the larger extension has been completed, the developer must notify the local planning authority as soon as reasonably practicable, giving the developer’s name, the address or location of the development and the completion date.
What the council is — and isn’t — assessing
This is worth stating clearly, because it’s the part people most often get wrong: prior approval for a larger extension is not the same as a full planning application.
There are really two separate questions going on.
First, the council can check whether the proposal qualifies for the larger Class A permitted development right in the first place. That means matters such as the dimensions and other applicable Class A restrictions still matter.
Second, if an adjoining owner or occupier objects, the particular prior approval question is whether the extension’s effect on the amenity of adjoining premises is acceptable.
The council isn’t given a general power at that stage to reopen the entire development as though it were deciding an ordinary planning application. The amenity judgement is deliberately narrower.
Equally, neighbours aren’t effectively being given a veto. An objection triggers the council’s assessment; it does not automatically prevent the extension.
Conditions can still apply
Even where the council confirms that prior approval is not required, grants prior approval, or the 42-day period expires without a decision, the underlying permitted development right still carries its other limitations and conditions.
For example, Class A contains requirements concerning matters such as the extension’s dimensions, position and the appearance of materials used in exterior work.
Prior approval therefore confirms — or deals with — one particular gateway. It does not convert a proposal that breaches another Class A requirement into lawful permitted development.
Prior approval and Lawful Development Certificates aren’t the same tool
A Lawful Development Certificate is a separate mechanism used to obtain formal confirmation that existing or proposed development is lawful — covered in detail in our companion article on that decision.
Prior approval, by contrast, is a mandatory part of particular permitted development rights. Where the relevant class requires prior approval, skipping that process isn’t simply a matter of accepting slightly more evidential risk in the way a homeowner might choose not to obtain an LDC.
For the larger home extension route, the neighbour consultation procedure has to be followed before development begins.
There is another distinction worth understanding. Successfully completing the larger-extension prior approval process does not necessarily provide the same comprehensive evidential determination as obtaining a Lawful Development Certificate that the whole proposal satisfies every permitted development requirement. If formal proof of overall lawfulness is important — perhaps for a borderline scheme or future transaction — an LDC may still be worth considering separately.
If the council refuses
If the council refuses prior approval, the applicant has a right of appeal under section 78 of the Town and Country Planning Act 1990.
For a larger home extension, the prior approval application falls within the householder appeal framework. A refusal appeal must normally reach the Planning Inspectorate within 12 weeks of the decision notice.
That is different from the 42-day fallback described above. If the council actually issues a refusal within the statutory period, the development cannot simply proceed because 42 days later passes; the refusal has to be dealt with, whether through appeal, redesign or another appropriate route.
The distinction worth carrying forward
“Permitted development” describes the legal planning permission being relied upon — permission already granted nationally for a specified category of development.
“Prior approval” describes a particular council process that some of those permitted development rights require before work can start.
They aren’t opposites, and they aren’t the same thing either.
Knowing which of the three positions — full planning application, permitted development with no further prior approval process, or permitted development subject to prior approval — applies to your specific project is the difference between a straightforward build and an expensive discovery, months in, that the work was never actually authorised to begin.
