HMO investing: licensing, planning and the rules that apply

A house in multiple occupation (HMO) lets rooms to several tenants who share facilities. Income comes from each room rather than from one household, which is why HMOs attract investors looking for higher income from a single building. The trade-off is regulation: licensing, planning, room sizes, fire safety and more intensive management. This guide covers the rules in England as they stand on 22 October 2026.

What counts as an HMO

GOV.UK describes an HMO as a property rented out by at least 3 people who are not from one household, for example a family, where tenants share facilities. The legal definition sits in section 254 of the Housing Act 2004, which sets out several tests. The most common, the standard test, is met where living accommodation that is not a self-contained flat is:

• occupied by people who do not form a single household;
• occupied by them as their only or main residence, with that being the only use of the accommodation;
• let for rent or other consideration, for at least one of them; and
• shared, with two or more households sharing one or more basic amenities, or lacking them.

The Act also covers self-contained flats that meet the same conditions, converted buildings, buildings declared HMOs by the council, and certain converted blocks of flats under section 257. Check how the tests apply to a specific property before you buy, not after.

Mandatory licensing

A licence is compulsory for a large HMO in England. Under the Licensing of Houses in Multiple Occupation (Prescribed Description) (England) Order 2018, an HMO must be licensed if it:

• is occupied by five or more people;
• who live in two or more separate households; and
• meets the standard test, the converted building test, or the self-contained flat test where the flat is not purpose-built in a block of three or more self-contained flats.

A licence lasts for a maximum of five years. Before granting one, the council checks that the house is suitable for the number of occupants and that the manager, whether you or an agent, is fit and proper. The fee is set by the council. Renting out an unlicensed large HMO can lead to an unlimited fine, and since 1 May 2026 the Renters' Rights Act 2025 has amended the offences for unlicensed HMOs and raised the maximum rent repayment order to two years' rent.

Additional and selective licensing

Councils can widen licensing beyond the mandatory scheme, so a property can need a licence even when it is below the five-person threshold.

Since 23 December 2024, a General Approval has meant councils in England no longer need the Secretary of State's confirmation before introducing a selective licensing scheme of any size, provided they consult for at least 10 weeks and meet the requirements of the Act. The practical effect is that licensing maps can change during the life of an investment, so check the council's current schemes and any consultations before buying.

Planning: Class C4 and Article 4 directions

Licensing and planning are separate systems, and an HMO can need both. In planning terms, a small HMO with not more than six residents falls in use class C4, while an ordinary home falls in class C3.

• Permitted development. Class L of the General Permitted Development Order 2015 allows a change of use from C3 to C4, and back, without a planning application, as long as it does not create two or more separate dwellings.
• Article 4 directions. Under article 4 of the same order, a council can make a direction so that the permitted development right does not apply in a particular area. Where one covers Class L, turning a family house into a small HMO needs a planning application.
• Larger HMOs. Class C4 is limited to six residents, so an HMO with more falls outside it and outside the Class L right. Planning advice from the council is needed.

Article 4 directions are made council by council, and can cover particular wards or a whole city. Check the council's planning pages and maps for the exact address, and check whether an existing HMO has a lawful planning use before relying on its income.

Room sizes

Since 2018, every HMO licence in England must include minimum sleeping room sizes. These are national minimums. Councils also judge whether the house is suitable for the number of occupants, given its size and facilities.

Any part of a room where the ceiling is lower than 1.5 metres is not counted in the floor area, which matters in loft rooms and under eaves. Licences must also require the licence holder to follow the council's scheme for storing and disposing of household waste.

Fire and safety

Schedule 4 of the Housing Act 2004 sets conditions that every HMO licence must contain. In England, the licence holder must:

• produce a gas safety certificate obtained within the last 12 months to the council each year, where gas is supplied;
• keep electrical appliances and furniture they provide in a safe condition, and ensure every electrical installation is in proper working order and safe for continued use;
• install a smoke alarm on each storey with a room used as living accommodation, and keep it in working order;
• install a carbon monoxide alarm in any room used as living accommodation that contains a fixed combustion appliance other than a gas cooker;
• give each occupier a written statement of the terms on which they occupy the property; and
• supply declarations about the safety and positioning of appliances, installations and alarms on demand.

The Management of Houses in Multiple Occupation (England) Regulations 2006 add duties for the manager: escape routes must be kept free from obstruction and in good repair, fire-fighting equipment and fire alarms must be kept in good working order, and notices showing the means of escape must be clearly displayed, unless the HMO has four or fewer occupiers. Detailed fire precautions for a particular building, such as the alarm system and fire doors, depend on the building and the council's requirements, so get them specified before you budget the conversion.

Tenancies under the Renters' Rights Act

HMO tenancies in England are covered by the reforms in force since 1 May 2026: periodic tenancies, no section 21, rent increases once a year by section 13 notice and new possession grounds. HMO landlords will also need to register each property on the Private Rented Sector Database during their region's window, starting from 15 December 2026. Our Renters' Rights Act guide covers the detail.

Financing an HMO

HMO lending is a specialist area, and each lender sets its own criteria. Without quoting rates or limits, these are the areas lenders may look at:

• whether the property holds the licence it needs, and its planning status;
• the number of lettable rooms and occupants, and the layout and shared facilities;
• your experience as a landlord, and whether you already hold other rental property;
• how the property will be valued, because a valuation based on the room income can differ from one based on comparable family homes; and
• the running costs. The Prudential Regulation Authority expects lenders to consider costs such as management fees, insurance, repairs, voids, utilities, gas and electrical certificates and licence fees when setting minimum rental cover.

Mortgage advice comes from an FCA-authorised mortgage broker. Our buy-to-let mortgages guide explains rental cover and stress testing, and the buy-to-let mortgage calculator shows how rent and rate interact.

The numbers behind an HMO

Room-by-room income is only one side. An HMO can carry costs that a single let does not: licence fees, higher-specification fire safety, furnishing for every room, cleaning of shared areas, and often utilities and broadband if bills are included. Management is more intensive, with more tenancies, more turnover and more contact. Model the full cost base in the deal analyser, and test any conversion budget in the refurbishment ROI calculator.

After purchase, PROXERA keeps each property's income, costs, certificates and licence dates together, so renewals such as the annual gas safety certificate and a licence that can run for up to five years are tracked rather than remembered. To discuss whether an HMO fits your plan, speak to PROXERA Wealth.