Permission in principle and technical details consent
Permission in principle fixes location, use and amount, and nothing else. No conditions can be attached, so everything moves to a single technical details consent application.
Permission in principle settles three things and nothing else: the location of the development, the use, and the amount of development. Everything else, including layout, access, drainage, ecology and design, is dealt with later at technical details consent. The route came from the Housing and Planning Act 2016 and is set out in the Town and Country Planning (Permission in Principle) Order 2017, and for a small housing site it can be a fast and low-cost way to establish that homes are acceptable here before spending money on a full application.
What permission in principle establishes
The grant fixes the principle. A permission in principle for up to four dwellings on a named parcel says that residential development of that scale on that land is acceptable, and the authority cannot go back on that when the technical details application arrives.
It says nothing about how the homes will look, where the access will be, how surface water will be handled or what the ecological mitigation will be. Those are all technical details.
The other thing to understand early is that a permission in principle cannot carry conditions. There is no mechanism to attach one, and no section 106 agreement can be tied to it either. Conditions and obligations arrive at the technical details stage. That single fact decides whether the route suits your site.
Site size and use limits
Permission in principle by application is a small-site route. It is available for housing-led development, meaning housing has to be the predominant use, on sites below the minor development thresholds: fewer than ten dwellings and less than one hectare.
It is not available where the development would require an environmental impact assessment, or where it would need an appropriate assessment under the habitats regime. Those exclusions matter on sites near designated ecological sites and in nutrient neutrality catchments, where the assessment cannot be deferred.
There is a second route entirely. Local planning authorities keep brownfield land registers, and entering a site in Part 2 of the register grants permission in principle without any application by the landowner. Sites entered that way can be larger, and the register is worth checking before applying, because your site may already carry the benefit.
| Feature | Permission in principle | Outline planning permission |
|---|---|---|
| Scope | Location, use and amount only | Principle plus any matters not reserved |
| Conditions | None can be imposed | Freely imposed |
| Section 106 | Cannot be attached | Can be attached |
| Determination period | Five weeks | Eight or 13 weeks |
| Second stage | Technical details consent | Reserved matters |
| Site limits | Minor housing-led development | No limit |
The application and its publicity
The application itself is short. You are seeking a decision on three matters, so the submission needs a location plan with the red line, a statement of the use and the amount of development, and the fee, which is charged on site area.
The authority must publicise the application, and the period for representations is shorter than the 21 days people expect on a normal application. The determination period is five weeks rather than eight, which is one of the route's genuine attractions.
Keep the description of development at the level the route operates at. Asking for "up to five dwellings" gives flexibility. Asking for "five two-storey detached houses with garages" invites the authority to treat design as part of the principle, which is not what the route is for.
Where the site has constraints that go to the principle rather than to the detail, expect the authority to refuse. An authority cannot condition its way round a flood risk objection at this stage, so if the answer depends on mitigation, the principle is not straightforward and permission in principle is the wrong instrument.
Technical details consent
The second stage is where the real work happens. A technical details consent application has to deal with everything a full application would, and the authority determines it in five weeks for minor development.
What it cannot do is reopen the principle. The location, the use and the amount are settled, and the authority's assessment is confined to whether the details are acceptable. That is the protection the route buys you.
The consequence is that the technical details application is all or nothing. There is no equivalent of reserving matters for later, so the drawings, the surveys and the supporting documents all have to be ready at the same time. Anyone treating it as a lightweight reserved matters submission has misread it.
Practically, that means the technical details application is where the Planning Statement, the Design and Access Statement and the technical reports all land at once. Budget for the whole package rather than for two small applications.
Time limits between the two stages
Permission in principle granted on an application has effect for three years. Permission in principle arising from an entry in Part 2 of a brownfield land register has effect for five years.
The technical details application has to be made within that period. Miss it and the permission in principle lapses, and there is no route to extend it. So the sequence is not "get the principle now and think about it later"; it is "get the principle now and have the technical work ready inside three years".
For a self-builder, three years is comfortable if the site is bought and the design team is appointed. It is not comfortable if the permission in principle is being used to market the site and a buyer takes 18 months to appear.
Where the route works, and where it does not
It works on straightforward infill and small brownfield sites where the only real question is whether housing is acceptable here at all. Establishing that in five weeks, for a fee based on site area, costs far less than an outline application supported by a full evidence base.
It works where the landowner wants to test the principle before committing to a design team, or before exercising an option.
It works less well where the site is constrained. Flood risk, heritage, protected species, highway access onto a difficult junction, contamination: any of these can mean the authority is unwilling to grant the principle without knowing how the issue is resolved, and it has no conditions available to bridge that gap.
It also works less well where you need the certainty a section 106 agreement provides. On a site where affordable housing or a highway contribution will be required, an outline permission with an agreement attached gives a clearer picture of the cost than a permission in principle that defers all of it.
Comparing it with an outline application
The honest comparison is about risk transfer rather than speed.
An outline application costs more at the start, takes longer, and can be granted with conditions and an agreement that between them define what you have to do. You end up with a permission whose obligations are known.
A permission in principle costs less at the start and is faster, but it defers every obligation and every condition to a single later application that has to succeed in one go. The principle is secure. The rest is not yet defined.
For a small, clean site, that trade is usually worth making. For anything with a technical issue at its centre, it usually is not. Work through the report types index before choosing, because if the list of documents you will need is long, the outline route probably suits the site better.
This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Enter your postcode on PlanScope to see which documents a technical details application would need.
Frequently asked questions
What does permission in principle actually grant?
Three things only: the location of the development, the use, and the amount of development. Layout, access, drainage, ecology and design are all technical details dealt with at the second stage. No conditions can be attached to a permission in principle, and no section 106 agreement can be tied to it.
Which sites can use the application route?
Housing-led development below the minor thresholds, meaning fewer than ten dwellings on a site under one hectare. It is not available where an environmental impact assessment or an appropriate assessment under the habitats regime would be required. Larger sites can obtain permission in principle through entry in Part 2 of a brownfield land register.
How long does permission in principle last?
Three years where it was granted on an application, and five years where it arises from an entry in Part 2 of a brownfield land register. The technical details consent application must be made within that period, and there is no mechanism to extend it once it has lapsed.
Can the council reopen the principle at technical details stage?
No. Location, use and amount are settled by the permission in principle, and the authority's assessment at the second stage is confined to whether the technical details are acceptable. That protection is the main value of the route, and it is why the earlier description of development should stay general.
Is permission in principle better than an outline application?
It depends on the site. On a straightforward infill plot where the only question is whether housing is acceptable, it is faster and cheaper. On a constrained site the absence of conditions is a problem, because the authority cannot grant the principle subject to mitigation and may simply refuse instead.
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.