What is an HMO? The meaning of a house in multiple occupation

HMO is short for house in multiple occupation. It's the legal term for a home shared by people who aren't one family — typically a house let room by room, a student house or a professional house share. The term covers flats as well as houses: a three-bedroom flat let to three unrelated sharers is an HMO.

The definition matters because HMOs come with extra legal duties: licensing in many cases, stricter fire safety, minimum room sizes and specific management rules. Many landlords run an HMO without realising it, simply by letting rooms to individual tenants.

Section 254 of the Housing Act 2004 sets out three tests, and section 257 adds a fourth. A building that meets any one of them is an HMO.

1. Standard test (the one most landlords meet): living accommodation occupied by people who don't form a single household, as their only or main residence, with rent paid by at least one of them, and with one or more basic amenities — a kitchen, bathroom or toilet — shared or missing.
2. Self-contained flat test: the same test applied to a single flat.
3. Converted building test: a building converted into one or more units that aren't self-contained, such as bedsits.
4. Section 257 HMO: a building converted into self-contained flats where the conversion didn't meet the 1991 Building Regulations (and still doesn't) and less than two-thirds of the flats are owner-occupied.

Not sure which applies? The free HMO checker runs the standard test from the number of people and households, and shows the licensing schemes at your postcode.

A household is a single person, or members of the same family living together: couples (married, civil partners or living together), and relatives including parents, grandparents, children, step-children, aunts, uncles, nephews, nieces and cousins. Foster children and live-in carers or domestic staff can also count as part of the family's household.

Students count as living there as their main home during term, so a student house share is normally an HMO.

• Three unrelated friends sharing a flat — HMO: 3 people, 3 households, shared kitchen.
• A couple plus one friend — HMO: 3 people, 2 households.
• A family of five — not an HMO: one household.
• Two friends sharing — not an HMO: a building occupied by only two people is exempt.
• You live in your own home with two lodgers — not an HMO. Take a third lodger and it becomes one.
• Five students in a house — a large HMO that needs a mandatory licence.
• A house split into self-contained flats in the 1980s, mostly let — possibly a section 257 HMO, depending on the building regulations it met.

Schedule 14 of the Act lists buildings that aren't HMOs even if they meet a test. The ones landlords meet most often:

• An owner-occupier living with their household and no more than two lodgers.
• A building occupied by only two people who form two households.
• Buildings managed or controlled by a council, housing association, police, fire service or NHS body.
• Student halls managed by a university or college under an approved code of practice.
• Buildings used by religious communities, and some buildings whose main use is something else.

Mandatory licence (everywhere in England): an HMO with 5 or more people forming 2 or more households needs a licence from the council. This covers houses and flats, except a purpose-built flat in a block of three or more flats. A licence lasts up to 5 years, and you need a separate one for each HMO.

Additional licensing: councils can require licences for smaller HMOs (3 or 4 people) in designated areas. Selective licensing can cover every rented home in an area, HMO or not.

Letting a licensable HMO without a licence can bring a civil penalty of up to £40,000 (since 1 May 2026) and a rent repayment order of up to two years' rent. The HMO licensing crash course covers the three schemes in detail.

Licensed or not, an HMO is covered by the Management of Houses in Multiple Occupation (England) Regulations 2006. In practice that means, among other things:

• Displaying the manager's name, address and phone number in the property.
• Keeping fire escape routes clear and fire precautions maintained.
• Keeping shared areas, fixtures and the water, gas and electricity supply in repair.
• Providing enough rubbish storage.

Licensed HMOs must also meet minimum bedroom sizes (6.51 m² for one adult, 10.22 m² for two) and any conditions the council attaches to the licence.

Planning is separate from licensing. A small HMO of 3 to 6 unrelated people falls in use class C4; turning an ordinary house (C3) into a C4 HMO normally doesn't need planning permission, unless the council has made an Article 4 direction removing that right, as many university towns have. An HMO for 7 or more people is “sui generis” and always needs planning permission. Check with the council's planning team before converting.