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HMOs: when does your property become one, and what rules apply?

Many landlords don't realise their property is an HMO. Here's the statutory definition, the licensing regimes and the extra rules that apply.

A House in Multiple Occupation (HMO) isn’t just a student house. The definition is broader than many landlords realise, and the compliance burden for an HMO is materially heavier than for a standard tenancy.

The statutory definition (England)

A property is an HMO if both:

  1. It’s occupied by three or more people forming two or more households, and
  2. Those occupiers share a kitchen, bathroom or toilet.

A “household” is either a single person or members of the same family (including couples, whether married or not). So a property let to three unrelated professionals is an HMO. A property let to a family of five is not.

The licensable HMO (mandatory licensing)

Since 1 October 2018, any HMO occupied by 5 or more people forming 2 or more households requires a mandatory licence from the local authority, regardless of how many storeys the property has. The old “three or more storeys” rule was scrapped in 2018 and catches out landlords who bought into HMO before then.

Additional and selective licensing

On top of mandatory licensing, many councils run:

  • Additional licensing — smaller HMOs (3–4 occupants) brought into the licensing regime by a local scheme.
  • Selective licensing — all rentals in a designated area, HMO or not, needing a licence.

These schemes vary widely. Birmingham, Liverpool, Newham, Bristol, parts of Greater Manchester and dozens of other councils run them. Check your specific local authority — a property compliant in one borough can be unlicensed in another just over the boundary.

What the licence typically requires

  • Minimum room sizes: 6.51 m² for a single adult, 10.22 m² for two adults sharing. Rooms under 4.64 m² can’t be used as sleeping accommodation at all.
  • Adequate amenities: a minimum ratio of bathrooms, toilets and kitchen facilities to occupants.
  • Fire safety: interlinked fire alarm system (typically grade D1 or A), fire doors on bedrooms and kitchens, emergency lighting in larger HMOs, fire-retardant furnishings.
  • Annual gas safety check (as for any rental with gas).
  • Five-yearly EICR (as for any rental).
  • PAT testing of landlord-supplied appliances — not strictly required by statute but routinely required by licence conditions.
  • A “fit and proper person” test for the licence holder.

Penalties for unlicensed HMOs

Unlimited fines on conviction. Rent Repayment Orders allowing tenants to reclaim up to 12 months’ rent. And critically: you can’t serve a (currently valid) Section 21 notice on an unlicensed HMO, and the grounds under the new Section 8 regime will also be affected by licensing status.

What’s coming

The Renters’ Rights Act 2025 will introduce a national PRS Database from late 2026, which will sit alongside local HMO licensing rather than replace it. And the EPC reforms confirmed in the Warm Homes Plan will extend EPC requirements to whole HMOs where individual rooms are let — a change that currently falls through a gap.

The common mistake

Assuming an HMO “only” means student houses. A three-bed flat let to three working professionals, unrelated, sharing a kitchen, is an HMO. The rules apply.

References and further reading

General guidance, not legal advice. HMO licensing rules vary significantly between councils — always check your local authority’s current scheme.