Moving between C3 and C4 and the Article 4 problem

A house occupied by three to six unrelated people sharing a kitchen or bathroom is a Class C4 house in multiple occupation, and the General Permitted Development Order 2015 allows you to move between Class C3 and Class C4 in both directions without planning permission. Class L of Part 3 of Schedule 2 does the work. The catch, and it is a large one, is that hundreds of councils have made article 4 directions removing the change from C3 to C4 across whole wards, and the direction is rarely obvious from the deeds or the estate agent's particulars.

Check for a direction before you exchange. Not after.

What Class C4 covers and where it ends

Class C4 is a small shared house or flat occupied by between three and six residents as their only or main residence, who are not a single household, and who share one or more basic amenities such as a kitchen, bathroom or WC.

Three thresholds matter. Below three occupiers the property is normally still C3, including the C3(b) and C3(c) arrangements covering small care groups and up to six people living together as a single household. At seven or more occupiers the use falls outside C4 altogether and becomes sui generis, which means planning permission is always required and there is no permitted change to fall back on. And where occupiers form a single household, such as a family of five, the number of people is beside the point.

The distinction between a household sharing and a set of unrelated tenants sharing is the one officers test. Separate tenancy agreements, separate rent, locks on bedroom doors and no shared food budget all point one way.

The two way permitted change in Part 3

Class L of Part 3 permits development consisting of a change of use of a building from Class C4 to Class C3, and from Class C3 to Class C4. No prior approval, no application, no fee.

Two conditions sit behind it. The use has to have been lawfully established in the first place, and the right can be withdrawn by an article 4 direction or by a condition on an earlier planning permission. That second route catches people out on newly built houses, where estate-wide conditions removing permitted development rights are common, and on conversions granted in the last fifteen years.

Read the decision notice for the property. If a condition removes the rights conferred by Part 3, Class L is gone regardless of what the council's article 4 map says.

Article 4 directions and how to find them

An article 4 direction is made under article 4 of the same Order and removes a specified permitted development right across a defined area. For HMOs the standard form removes the C3 to C4 change, so that creating a small HMO needs a full planning application. Directions of this kind now cover large parts of many university towns and cities, and several authorities have made them borough-wide.

Three places to look, in this order. The council's own planning policy pages, which usually carry a map and the direction document with its date. The national article 4 direction dataset published on planning.data.gov.uk, which is useful for a first pass but is only as current as the authority's return. And the local land charges search, which is the answer that actually protects a purchase.

A direction has a date it came into force. Uses lawfully established before that date are unaffected, which is why establishing the existing use matters so much.

Evidence of the existing lawful use

If the house was already operating as a C4 HMO before the direction took effect, that use is lawful and continues. Proving it is your problem, not the council's.

The formal route is an application for a certificate of lawfulness of existing use or development under section 191 of the Town and Country Planning Act 1990. The evidence that persuades officers is documentary and boring: tenancy agreements running back in an unbroken chain, council tax or HMO licence records, utility bills showing occupation, room-by-room inventories, and a sworn statement from the landlord or managing agent covering the periods the paperwork does not.

Gaps are fatal to a continuous use argument. A year let to a single family in the middle of the chain can reset the position entirely.

Note the enforcement time limits have changed. The Levelling-up and Regeneration Act 2023 moved to a ten year limit for enforcement action in England for breaches of planning control, replacing the earlier split between four and ten years. Commencement and the treatment of breaches that began before the change are technical, so take advice on a specific chain of evidence rather than relying on a rule of thumb. Our explainer on how the prior approval procedure actually works covers the neighbouring question of when a formal application is needed at all.

Licensing is a separate regime

Planning permission and HMO licensing are different systems with different tests, and satisfying one says nothing about the other.

Mandatory licensing under the Housing Act 2004 applies to HMOs occupied by five or more people forming two or more households, whatever the number of storeys. Many councils also operate additional licensing covering smaller HMOs, and selective licensing covering all private rentals in defined areas. Licensing looks at room sizes, amenity standards, fire precautions and management. Planning looks at the use of the land.

A licensed HMO is not thereby a lawful one in planning terms. Councils increasingly cross-check the two registers, and a licence application is a common way for an unauthorised change of use to come to the planning department's attention.

Reverting from C4 back to C3

Class L runs both ways, so a C4 HMO can revert to a single dwelling without permission even inside an article 4 area, because the typical direction only removes the C3 to C4 direction of travel.

That sounds convenient and is a one-way door. Once the property has reverted to C3 in an article 4 area, going back to C4 requires a planning application, judged against whatever concentration policy the council now operates. Many authorities apply a threshold policy refusing new HMOs where more than a stated percentage of properties within a given radius are already in that use.

If the HMO use is the value in the asset, do not let it lapse while the house is being refurbished or sold. Keep it occupied, keep the licence current, and keep the paperwork.

Applying where the right has gone

Where a direction bites, you are making a full planning application for a change of use, and the supporting documents are predictable.

A Planning Statement should deal with the council's concentration policy directly, with a plotted radius and the evidence behind the percentage. Amenity standards come next: room sizes against the council's published standards, communal space, and a layout drawing showing how six people live in the house without the kitchen becoming a corridor. Refuse storage is a frequent refusal reason on its own, so show a bin store with capacity for the collection cycle and a drag distance to the kerb.

Parking is where most of these applications turn. A Parking Survey carried out to the Lambeth methodology, with overnight counts on a midweek night and a weekend night outside school holidays, gives the highway officer something to work with instead of a policy standard applied blind.

Enter your postcode on PlanScope to see which reports a change of use application is likely to need. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.

This is general guidance, not legal advice. A certificate of lawful development is the only formal way to confirm that a use is lawful, and you should check the position with your local planning authority or a qualified professional before relying on it.