What is an HMO?
An HMO, or house in multiple occupation, is broadly a property lived in by 3 or more people who form more than one household and who share basic facilities such as a toilet, bathroom or kitchen. That's how government guidance states the definition for most purposes, and it captures the classic shared house: three friends renting together, a professional house share, or most student houses.
The precise legal test sits in section 254 of the Housing Act 2004. Under the standard test, a property is an HMO where the living accommodation isn't a self-contained flat, the occupiers don't form a single household, they occupy it as their only or main residence, rent (or other consideration) is payable, and two or more households share a basic amenity, a toilet, personal washing facilities or cooking facilities, or the accommodation lacks one. Purpose-built student halls managed by universities are treated differently, as the Act carves out buildings controlled by specified educational establishments for most purposes.
Whether your home counts matters, because HMOs carry extra duties for landlords, extra standards for the property, and extra remedies for you if things go wrong.
What counts as a single household?
Family, essentially as you'd expect. Section 258 of the Housing Act 2004 treats members of the same family as a single household: couples (married, civil partners or living together) and relatives including parents, grandparents, children, grandchildren, brothers, sisters, uncles, aunts, nephews, nieces and cousins, with half-relatives counted too.
So a couple renting with one friend is 3 people in 2 households, which can make the property an HMO. A family of four is one household, so their home isn't an HMO no matter how many of them there are. Mixed groups are common in practice, and the household count, not just the head count, is what decides the question.
When does an HMO need a licence?
There are three licensing regimes, and which applies depends on the property and the council area:
Mandatory licensing applies across England to HMOs occupied by 5 or more people in 2 or more households. The rule comes from a 2018 Order that took effect on 1 October 2018 and removed the old three-storey requirement, so size no longer matters: a bungalow shared by five people in separate households needs a licence just as a tall townhouse does.
Additional licensing lets a council extend licensing to smaller HMOs, such as 3- and 4-person shares, in designated areas where a large proportion of HMOs are being managed ineffectively (section 56 of the Housing Act 2004).
Selective licensing (section 80) goes further still: in designated areas, every privately rented house needs a licence, HMO or not, based on conditions such as low housing demand or persistent anti-social behaviour.
Because two of the three regimes depend on where you live, the only reliable way to know whether your home should be licensed is to ask your council. Every local housing authority must keep a public register of licences granted, open to inspection, so you can check whether your address (or your landlord) appears on it.
What standards must a licensed HMO meet?
HMO managers carry specific legal duties under the management regulations, whether or not tenants ever read them. The manager must display their contact details in the property, maintain fire safety measures, keep the water supply and drainage in order, arrange an annual gas safety certificate and an electrical inspection at least every 5 years, maintain the common parts, and manage waste disposal.
Licensed HMOs also have minimum sleeping room sizes: 6.51 square metres for one person over 10 years old, 10.22 square metres for two, and 4.64 square metres for a child under 10, with rooms under 4.64 square metres not usable as sleeping accommodation at all. Councils attach conditions to licences and can inspect, assess hazards under the Housing Health and Safety Rating System, and serve improvement notices requiring works within a set period.
Licence applicants must also pass a fit and proper person test before a licence is granted, which is designed to keep serious offenders out of the sector; repeat or serious offenders can also face banning orders under the Housing and Planning Act 2016.
What happens if a landlord operates an unlicensed HMO?
Quite a lot, and most of it favours the tenant:
- Criminal liability. Operating a licensable HMO without a licence is an offence carrying an unlimited fine on summary conviction (section 72 of the Housing Act 2004). Defences exist, including a pending valid licence application and, since 1 May 2026, a reasonable excuse defence.
- Civil penalties. Instead of prosecuting, councils can impose a financial penalty of up to £40,000 per offence, a cap raised from £30,000 with effect from 1 May 2026.
- Rent repayment orders. This is the remedy that puts money in tenants' pockets. If your landlord committed the unlicensed HMO offence, you can apply to the First-tier Tribunal for a rent repayment order covering rent you paid over a period of up to 2 years while the offence was being committed. You must apply within 2 years of the offence (extended from 12 months on 1 May 2026), the landlord doesn't need to have been convicted first (the tribunal must simply be satisfied beyond reasonable doubt that the offence occurred), and orders can now be made against superior landlords as well as your immediate one.
Your tenancy itself remains valid even if the property should have been licensed, and eviction protections apply in the normal way.
Does anything else change because I live in an HMO?
Your core rights are the same as any other renter. Your deposit must be protected in an authorised scheme within 30 days, with compensation of between 1 and 3 times the deposit available through the court if it wasn't. Repairs, gas safety and the other basics apply exactly as they do in a self-contained flat, and since 1 May 2026 the Renters' Rights Act 2025 protections, including the end of Section 21 evictions, apply to HMO tenants too. The Act also extends the Decent Homes Standard to the private rented sector on a phased basis.
What's genuinely different is the extra enforcement layer. If your shared house is cold, overcrowded, unsafe or badly managed, the licensing system gives your council direct power over the landlord, and gives you the rent repayment route if the landlord should have had a licence and didn't. Checking the licence register takes five minutes and is the single most useful thing an HMO tenant can do.