The basics: what prior approval is
Permitted development (PD) rights allow certain types of development without needing to apply for full planning permission. But for some PD classes, the government requires you to notify the local planning authority first and give them a limited period to assess specific aspects of the proposal.
This is prior approval. You're not seeking permission in the traditional sense — the right to develop already exists in law. You're asking the LPA to confirm either:
- Prior approval is not required — the LPA has reviewed the notification and is satisfied. You can proceed.
- Prior approval is required — the LPA needs to assess certain specified matters before you can proceed. They then issue a decision (approval or refusal) based only on those matters.
The LPA cannot refuse a prior approval on grounds they could raise for full planning permission. Their assessment is strictly limited to the matters specified for that PD class — transport impact, flood risk, contamination, noise, and so on, depending on the class. They cannot object on design grounds, visual amenity, or loss of employment use (for Class MA), for instance.
Important: Prior approval rights only apply in England under the Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended). Scotland, Wales, and Northern Ireland have separate PD frameworks with different rules.
The main prior approval classes
| Class | What it covers | Determination period |
|---|---|---|
| Class MA | Commercial, business and service uses (Use Class E) to residential (C3). Introduced 2021, replaced Class O and expanded scope significantly. | 56 days |
| Class Q | Agricultural buildings to residential (C3). Up to 5 dwellings per holding. Maximum 465m² residential floorspace. | 56 days |
| Class R | Agricultural buildings to flexible commercial use (A1, A2, A3, B1, B8, C1, D2). | 56 days |
| Class A (Part 1) | Larger home extensions — single-storey rear extensions beyond the standard PD limits (up to 8m detached, 6m semi/terraced). | 42 days |
| Class AA (Part 1) | Additional storeys on dwellinghouses — up to 2 storeys on a detached house built between 1948 and 2018. | 56 days |
| Class A (Part 20) | Additional storeys on existing commercial buildings (upward extensions to create new homes). | 56 days |
| Class ZA | Demolition of buildings and replacement with homes. Limited to specific building types built before 1990. | 8 weeks |
| Class G (Part 3) | Betting offices, pay day loan shops, or launderettes to mixed use or residential. | 56 days |
Class MA in detail: the big one
Class MA is the most commercially significant prior approval class introduced in recent years. It allows any building in Use Class E — which covers offices, retail, restaurants, gyms, clinics, crèches, and more — to be converted to residential use.
Key conditions:
- The building must have been in Use Class E (or the previous A, B1 uses it replaced) for at least 2 years
- It must have been vacant for at least 3 months prior to the prior approval application
- The floorspace cannot exceed 1,500m² (though this can be circumvented via phased applications)
- Article 4 directions can remove Class MA rights — check the local authority's Article 4 status before proceeding
The LPA can only assess: transport impacts, contamination, flooding, noise, impact on provision of retail, daylight/sunlight, and the impact on the character or sustainability of the area. They cannot refuse on design grounds or because they'd prefer to retain commercial use.
Class Q in detail: agricultural to residential
Class Q remains one of the most-used routes for rural residential development. It converts existing agricultural buildings — typically steel-framed portal barns — to residential use without needing to go through the full planning process.
Key limits:
- Up to 5 dwellings per agricultural unit
- Maximum 465m² total residential floorspace across all units
- Must be on land that has been in agricultural use — Article 2(3) land (National Parks, AONBs, etc.) has additional restrictions
- The building must be "capable of functioning as a dwelling" — structural interventions beyond conversion are not permitted development
The "capable of functioning" test is where most Class Q applications encounter problems. LPAs have interpreted this narrowly in some areas, refusing applications where significant structural work would be needed. Appeal decisions have refined this test over time.
How to query prior approval applications via API
Prior approval applications appear in the PlanWire dataset as a distinct application type. You can filter for them directly:
# All prior approval applications in a council area curl "https://api.planwire.io/v1/applications\ ?council_id=north-yorkshire\ &application_type=Prior+Approval\ &days=90&limit=50" \ -H "X-API-Key: your_api_key" # Class Q agricultural conversions (filter by description keyword) curl "https://api.planwire.io/v1/applications\ ?q=Class+Q&application_type=Prior+Approval\ &days=365" \ -H "X-API-Key: your_api_key" # Class MA office-to-residential (commercial to C3) curl "https://api.planwire.io/v1/applications\ ?q=Class+MA&application_type=Prior+Approval\ &status=Approved&days=365" \ -H "X-API-Key: your_api_key"
What the outcome statuses mean for prior approvals
Prior approval applications use different status vocabulary to full planning applications:
- Prior Approval Not Required — LPA confirmed no further assessment needed. You can proceed immediately.
- Prior Approval Required / Approved — LPA assessed the specified matters and is satisfied. You can proceed, subject to any conditions attached.
- Prior Approval Required / Refused — LPA assessed the specified matters and found grounds to refuse. You have 6 months to appeal.
- No Objection — used by some portals to mean the same as Prior Approval Not Required.
Why developers track prior approvals
Prior approval applications are high-value signals for several audiences:
- Property investors: A Class MA approval on a vacant office building means someone is converting it — the residential units will come to market. Knowing this early helps with sourcing or competing bids.
- Architects and project managers: Class Q approvals mean barn conversions are proceeding — there's often a pipeline of professional services needed.
- Tradespeople and contractors: Approved prior approvals are confirmed projects without the uncertainty of the planning process. They represent near-certain work.
- PropTech products: Prior approvals are excellent signals for pipeline analytics — understanding how much new residential stock is coming through the PD route versus full planning.
Article 4 directions: where prior approvals don't apply
LPAs can remove specific permitted development rights within their area by issuing an Article 4 direction. For Class MA, many London boroughs and some other urban LPAs have issued Article 4 directions covering office-to-residential conversions, effectively requiring full planning permission instead.
Before relying on a prior approval route for a specific site, always check whether an Article 4 direction is in force. This is available from the local planning authority directly or via national Article 4 direction registers.