Prior approval: the clock, deemed consent and the risks

Miss the prior approval 56 day deadline and, for most classes in Part 3 of the General Permitted Development Order, the developer may lawfully begin the development without a decision notice ever being issued. That sounds like a gift. It is closer to a trap, because deemed consent only helps you if the application was valid, the development qualified under the class in the first place, and you can prove both of those things to a lender two years later.

How a prior approval application differs from a planning application

A prior approval application is not a request for planning permission. The permission already exists, granted by the Town and Country Planning (General Permitted Development) (England) Order 2015. What you are asking the local planning authority to do is approve a short list of specified matters before you use that permission.

Three consequences follow from that, and all three catch people out.

The authority cannot refuse because it dislikes the proposal in general policy terms. It can only refuse on the matters the class allows it to consider. Adopted local plan policy on housing mix, affordable housing, design quality or town centre vitality is simply outside its hands, which is why prior approval routes remain attractive even where local policy is hostile.

There is no publicity requirement in the ordinary sense for every class, although Part 3 requires the authority to consult certain bodies and to display a site notice or notify adjoining occupiers, and representations received have to be taken into account on the matters in scope.

And the clock runs differently. A planning application has a target determination period that the authority routinely asks you to extend. A prior approval period is a hard statutory deadline with a consequence attached.

The clock, and when the 56 days actually start

For Part 3 classes, including Class MA (commercial, business and service use to dwellinghouses) and Class Q (agricultural building to dwellinghouse), paragraph W of Part 3 sets the procedure. The authority has 56 days beginning with the day after it receives the application. Within that period it must give the applicant written notice of its determination, either granting prior approval, refusing it, or stating that prior approval is not required.

If no notice is given, development may begin. The period can be extended only by written agreement between applicant and authority, so a telephone conversation with the case officer achieves nothing.

Two details decide most disputes. The first is receipt: the clock starts from the day the authority received a valid application with the correct fee and all the information the class requires, not from the day you pressed submit. The second is notice given: the test is whether the authority gave notice, not whether you read it. A decision emailed on day 55 to an address on your own application form counts, even if it went to a project email nobody monitors.

Other parts of Schedule 2 use different periods. The larger home extension procedure in Part 1 Class A runs for 42 days. The agricultural determination in Part 6 turns on 28 days for the question of whether approval is required at all. Check the paragraph for the class you are using rather than assuming 56 days everywhere.

What the authority is allowed to consider

Each class lists its own matters. Class MA, the route most conversions now use, limits the authority to transport impacts (particularly highway safety), contamination risk, flooding risk, noise from commercial premises affecting future residents, the provision of adequate natural light in all habitable rooms, and, in a conservation area, the impact of the loss of a ground floor commercial use. Where the building is 18 m or more in height, fire safety information is also required.

That list is the whole of the argument. A noise objection from an adjoining industrial unit is in scope, so an acoustic report prepared by a suitably qualified author is usually the single most useful document to supply; councils expect a Noise Impact Assessment to follow recognised methodology rather than a general reassurance. Surface water risk is in scope, so a site in Flood Zone 2 or 3 will need a Flood Risk Assessment addressing the vulnerability change from commercial to residential. Parking stress on its own is not in scope unless it bears on highway safety.

Natural light is the condition that fails most Class MA schemes. Every habitable room needs it, which rules out deep plan floorplates with internal bedrooms no matter how the layout is drawn.

Why relying on deemed consent is risky

The deemed route produces development that is lawful and a paper trail that is not persuasive. Several problems follow.

1. If the application was incomplete, the 56 days may never have started, and the development you began on day 57 is unauthorised.
2. Prior approval does not cure a failure to qualify. If the building was not in a qualifying use for the required period, or the vacancy condition was not met, no amount of silence from the authority makes the conversion permitted development.
3. Lenders, insurers and buyers want a document. Explaining paragraph W to a conveyancer under time pressure is not a position you want to be in.
4. The authority can still take enforcement action if it later concludes the development was never within the class, and the four and ten year immunity periods under the Town and Country Planning Act 1990 have been changed by the Levelling-up and Regeneration Act 2023, so do not treat the old time limits as settled.

The answer, where the stakes justify it, is a certificate of lawfulness of proposed use or development under section 192 of the 1990 Act. That is the only formal way to confirm that works are lawful, and it produces a certificate you can hand to a solicitor.

Fees and what has to arrive with the application

Prior approval fees are set by the national fee regulations, vary by class, and are indexed, so check the current schedule on the Planning Portal before you transfer anything. A fee short by a few pounds is the most common reason an application is treated as never received. Where the proposal involves several dwellings, the fee is calculated per unit up to a cap for some classes, and some reductions and exemptions apply more widely than people realise, which is covered in our note on planning fee exemptions and reductions.

Beyond the fee, the class dictates the documents. Class MA needs a written description, a plan identifying the site, the developer's contact details, and the evidence on each in-scope matter. Class Q needs a floor plan showing the extent of works and evidence that the building was in agricultural use on the relevant date. Send a site plan at a recognised scale with the application boundary edged in red, because an unscaled sketch is a validation refusal in most authorities.

Appealing a refusal, and the non-determination question

A refusal of prior approval can be appealed to the Planning Inspectorate. The inspector considers the same restricted list of matters the authority was limited to, which makes these appeals narrower and often quicker than a full planning appeal, and makes the quality of your evidence on those specific matters decisive.

Non-determination is the odd case. Where the class provides for deemed consent, there is nothing to appeal, because silence has given you what you asked for. Where it does not, the ordinary appeal routes apply, and the choice between appealing and waiting is a judgement about your relationship with the authority as much as about the law. That trade-off is set out in our piece on appealing non-determination or waiting.

The conditions written into the class itself

Prior approval is not the end of the obligations. Each class carries conditions that bind the development whether or not anybody mentions them.

Class MA development must be completed within three years of prior approval. Class Q limits the amount of floorspace and the extent of building operations, and restricts later residential permitted development rights. Several classes remove rights under other parts of Schedule 2 once used. Breaching one of those conditions is a breach of planning control even though no planning permission was ever granted, and the authority can serve a breach of condition notice without a right of appeal.

Read the class in full on legislation.gov.uk, including the paragraph W procedure and the interpretation paragraphs, before you rely on a summary of it. If you want to see which supporting documents a conversion of this type usually needs, you can enter the postcode and work through the site's constraints first.

This is general guidance, not legal advice, so check the position with your local planning authority or a qualified professional before relying on it. 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.