Is a house shared by three friends an HMO?

Usually, yes. Three friends who are not related form three households, so if they share a kitchen, bathroom or toilet and live there as their main home, the house meets the HMO definition. Whether it needs a licence depends on the numbers and on your council's schemes.

Does a couple count as one household?

Broadly, yes. A couple living together count as one household but two occupiers. So a couple renting a room in a shared house add two people to the occupier count but only one household to the household count.

Do all HMOs need a licence?

No. Mandatory licensing covers HMOs with 5 or more occupiers from 2 or more households. Smaller HMOs need a licence only where the council runs an additional or selective scheme. The HMO management regulations apply either way.

Can a flat be an HMO?

Yes. A flat shared by 3 or more people from more than one household can be an HMO under the self-contained flat test. A converted block can also be a section 257 HMO if the conversion fell below the standards of its time and fewer than two-thirds of the flats are owner-occupied.

What is an HMO? The legal definition explained

What is the legal definition of an HMO?

A house in multiple occupation, usually shortened to HMO, is a building or part of a building let to people who do not form a single household and who live there as their only or main home. The definition is in section 254 of the Housing Act 2004, with exceptions in Schedule 14. GOV.UK sums it up as at least three tenants, from more than one household, sharing facilities.

Three things decide whether a typical shared house is an HMO:

The number of people. At least 3 occupiers. Schedule 14 takes out a building occupied by only two people who form two households, so two unrelated sharers do not create an HMO.
The number of households. The occupiers must come from 2 or more households. Broadly, members of the same family count as one household and unrelated people are separate households. The Act sets out who counts as family, so take advice on unusual arrangements.
Shared facilities. Under the main test, the occupiers share at least one basic amenity, meaning a toilet, personal washing facilities or a kitchen, or the accommodation lacks one of them.

It makes no difference whether the occupiers have a tenancy each or one joint tenancy for the whole house. The test looks at who lives there and what they share, not at the paperwork.

What is the standard test for an HMO?

The standard test is the route that catches most shared houses and flats. A building, or a part of one, meets it when the people living there do not form a single household, they occupy it as their only or main home, and at least one basic amenity is shared or missing.

A familiar example is a terraced house with five bedrooms, each let to a different person, with a shared kitchen and bathroom. Each person may have a lock on their own door and their own agreement, but the shared kitchen keeps the house inside the standard test.

Two points often surprise landlords:

Adding an en-suite shower room to every bedroom does not take a house out of the definition if the occupiers still share a kitchen.
A group of friends who rent a whole house together on one agreement are still separate households if they are not related. Three or more of them sharing facilities can make the house an HMO.

Because the test looks at actual occupation, a house can become an HMO without any building work, for example when a third unrelated sharer moves in.

What other tests can make a building an HMO?

The Housing Act 2004 has several other routes into the definition besides the standard test:

The self-contained flat test. This applies the same ideas to a single flat. A flat shared by 3 or more people from more than one household can be an HMO in its own right, even if the rest of the building is not.
The converted building test. This covers a building that has been converted and contains one or more units of accommodation that are not self-contained, such as bedsits. No sharing of amenities is needed for this test.
An HMO declaration. In some circumstances a council can formally declare a building to be an HMO.
Section 257 HMOs. These are converted blocks of self-contained flats that fall below the building standards that applied when they were converted.

How do section 257 HMOs work?

A building converted into self-contained flats is a section 257 HMO when two things are true. First, the conversion did not meet the building standards that applied when it was done, and it still does not. For conversions carried out before June 1992, the benchmark is the 1991 Building Regulations. Second, fewer than two-thirds of the flats are owner-occupied, which means held on a lease of more than 21 years or by the freeholder.

Section 257 HMOs are treated differently from shared houses. They fall outside the mandatory licensing description, they are excluded from planning use class C4, and the 2006 HMO management regulations do not apply to them. If you own a converted block, check its position with the council rather than assuming the shared-house rules apply.

What is the difference between a small HMO and a large HMO?

The terms small HMO and large HMO are used in two different ways, which causes a lot of confusion. Planning and licensing draw their lines at different numbers.

In planning, a small HMO is use class C4: a house used by 3 to 6 unrelated residents as an HMO. A large HMO has 7 or more residents. It falls outside class C4, is classed as sui generis (a use of its own kind), and always needs planning permission.

In licensing, the line is 5 people. An HMO with 5 or more occupiers forming 2 or more households needs a mandatory licence. Smaller HMOs need a licence only if the council has an additional or selective licensing scheme that covers them.

Occupiers	Planning position	Licensing position
3 or 4	Small HMO (C4). A change from a family house is usually permitted development, unless an Article 4 direction applies.	Licence needed only under an additional or selective scheme.
5 or 6	Small HMO (C4), as above.	Mandatory licence.
7 or more	Large HMO (sui generis). Planning permission needed.	Mandatory licence.

So a six-person house is a small HMO for planning but still needs a mandatory licence. Always check both regimes separately.

What are the common misconceptions about HMOs?

“It is only an HMO if five or more people live there.” Five is the mandatory licensing threshold, not the definition. Three people from two or more households who share facilities can be enough.
“If it does not need a licence, the HMO rules do not apply.” The HMO management regulations apply to every HMO in England, licensed or not, apart from section 257 blocks.
“A licence covers planning.” Licensing and planning are separate regimes with different thresholds. A licence does not give planning permission, and planning permission does not give you a licence.
“En-suites stop it being an HMO.” Not if the kitchen is shared.
“A couple counts as two households.” A couple living together count as two occupiers but, broadly, one household.
“Flats cannot be HMOs.” A shared flat can meet the self-contained flat test, and some converted blocks are section 257 HMOs.

Check the position before you let, and again whenever the number of occupiers changes.

Why does HMO status matter for licensing and planning?

Once a house is an HMO, several sets of rules switch on.

Licensing. If the house needs a licence and does not have one, the person in control of it or managing it commits an offence. The maximum civil penalty rose to £40,000 on 1 May 2026, and from that date the offence can also reach superior landlords further up a letting chain. Tenants and councils can apply for rent repayment orders of up to 2 years' rent. Our guide to HMO licensing covers the detail.

Planning. A change from a family house (C3) to a small HMO (C4) is usually permitted development, but an Article 4 direction removes that right, and a large HMO always needs permission. See HMO planning and Article 4.

Building regulations. Converting a house for HMO use often involves building work, and it may involve a material change of use, which brings in building regulations on fire safety, sound insulation and more.

How does HMO status affect council tax and day-to-day duties?

Management duties. The Management of Houses in Multiple Occupation (England) Regulations 2006 place duties on whoever manages the house: giving and displaying contact details, keeping escape routes clear, maintaining fire equipment, common parts, the water supply, drainage and each occupier's room, and providing waste facilities. Our guide to HMO management duties goes through them.

Room sizes. Licensed HMOs must meet national minimum bedroom sizes, and councils can set higher local standards. See HMO room sizes.

Fire safety. The Regulatory Reform (Fire Safety) Order 2005 covers the common parts of HMOs, and the responsible person must carry out a fire risk assessment. Fire services can take different views on whole-house shared lets. See HMO fire safety.

Council tax. Where rooms are let individually, the owner, not the occupiers, is usually liable for council tax under the owner liability rules (Class C). For a whole house let on one joint tenancy, the occupiers may be liable instead, unless the property was built or adapted for multiple occupation. The council decides each case.

Student lets. The Ground 4A possession ground for student lets is available only where the property is an HMO or is in one.

How can I check whether my property is an HMO?

Work through these questions for the address:

How many people will live there as their only or main home?
How many households do they form?
Will they share a kitchen, bathroom or toilet, or is one missing from their own accommodation?
Is the building a conversion into flats? If so, did it meet building standards when converted, and how many flats are owner-occupied?
Does the council run an additional or selective licensing scheme covering the street?
Is there an Article 4 direction for HMOs in the area?

Our HMO licensing checker gives a quick first view of the licensing position. For a house you already let, an HMO compliance audit checks the room sizes, fire safety and licence conditions against the council's standards. Where a case is borderline, ask the council's private housing team for its view in writing.

Sources

This guide explains the rules in England as we understood them in October 2026. It is general information, not legal or financial advice. Check with your council and take professional advice for your own situation.

What is an HMO?