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A House in Multiple Occupation, commonly referred to as an HMO, is a property rented out by at least three people who are not from the same household but share facilities such as a bathroom or kitchen. Managing an HMO carries a set of obligations that go beyond standard residential letting, and depending on the size and occupation of the property, you may be legally required to hold a licence from your local council. Operating an HMO without the required licence is a criminal offence. This guide explains how HMOs are defined, the three tiers of licensing that apply, the conditions attached to licences, the mandatory minimum room size requirements introduced in 2018, additional and selective licensing schemes, and the consequences of non-compliance.
What is an HMO?
A property is a House in Multiple Occupation if at least three tenants live there forming more than one household, and they share toilet, bathroom, or kitchen facilities with other tenants. A large HMO is one where at least five tenants live there forming more than one household and share those facilities. A household is defined as a single person or members of the same family living together. Family includes married or cohabiting couples, relatives, half-relatives, and step-parents and step-children. (Source: Private renting, GOV.UK)
For the purposes of mandatory licensing, the statutory definition comes from section 254 of the Housing Act 2004. A building meets the standard HMO test if it is a building in which more than one household has living accommodation other than self-contained flats, and either at least two households share a basic amenity or the living accommodation is lacking in a basic amenity. Basic amenities are defined as a toilet, personal washing facilities, or cooking facilities. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
This definition applies not just to traditional bedsit-type HMOs but also to shared houses that function as conventional homes in terms of their physical layout but are occupied by multiple households. The type of tenancy agreement in place is not relevant to whether a property qualifies as an HMO. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Which HMOs require mandatory licensing?
Mandatory licensing is governed by the Licensing of Houses in Multiple Occupation (Prescribed Description) (England) Order 2018, which came into force on 1 October 2018. Before that date, mandatory licensing only applied to HMOs of three or more storeys. From 1 October 2018, it was extended to include properties of one and two storeys as well. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
For mandatory licensing to apply, the HMO must be occupied by five or more persons from two or more separate households. The property must also fall within one of the building categories covered by the Order, which are HMOs meeting the standard test under section 254(2) of the Housing Act 2004, HMOs meeting the self-contained flat test under section 254(3) but which are not purpose-built flats in a block of three or more self-contained flats, and HMOs meeting the converted building test under section 254(4). (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Converted blocks of flats, known as section 257 HMOs, are not subject to mandatory licensing. However, individual flats within such converted blocks can require a mandatory licence if they individually meet the standard test for an HMO. Local authorities have discretion to bring section 257 HMOs into additional licensing schemes. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Landlords whose HMOs fell within the extended definition from 1 October 2018 committed a criminal offence if they failed to apply for a licence or a temporary exemption notice by that date. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Additional licensing and selective licensing
Mandatory licensing covers the larger and higher-risk end of the HMO market. Two further licensing schemes apply more locally and can catch properties that are not subject to mandatory licensing.
Additional HMO licensing can be introduced by a local housing authority where it believes there is a need to license certain HMOs not subject to mandatory licensing, such as section 257 HMOs or purpose-built flats in blocks of three or more self-contained flats. An additional licensing scheme must be introduced in line with the statutory requirements under Part 2 of the Housing Act 2004 and will be specific to a designated area or type of property within the local authority's district. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Selective licensing is a separate regime under Part 3 of the Housing Act 2004 that can require all landlords of privately rented properties in a designated area to obtain a licence, regardless of whether the property is an HMO. Some single-family dwellings in areas with high levels of deprivation, poor housing quality, or antisocial behaviour may fall within a selective licensing zone. You should always check with your local council whether any licensing scheme applies to your area. (Source: How to Rent guide, DLUHC, October 2023)
The licence application and fit and proper person test
A local housing authority is under a duty to grant an HMO licence if it is satisfied on four points. First, the property is reasonably suitable for occupation by the number of households or persons specified, or can be made suitable by imposing conditions. Second, the proposed licence holder is the most appropriate person and is a fit and proper person to hold the licence. Third, the proposed manager is the person having control of the property or their agent or employee, and is a fit and proper person to manage the property. Fourth, the proposed management arrangements are otherwise satisfactory. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
The fit and proper person assessment is a significant filter. A person may not be considered fit and proper if they have criminal convictions relating to violence, fraud, drugs, or sexual offences, or if they have been found guilty of unlawful discrimination, or have committed breaches of housing legislation or codes of practice.
Mandatory licence conditions
Every HMO licence issued under mandatory or additional licensing must include a set of mandatory conditions set out in Schedule 4 of the Housing Act 2004. These cover the provision of smoke alarms and carbon monoxide alarms, gas safety, and the safety of electrical appliances and furniture. From 1 October 2018, two additional mandatory conditions were introduced by the Licensing of Houses in Multiple Occupation (Mandatory Conditions of Licences) (England) Regulations 2018. These are minimum sleeping room sizes and waste disposal requirements. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Minimum sleeping room sizes
From 1 October 2018, all HMO licences issued under Part 2 of the Housing Act 2004 must include conditions specifying the minimum floor area for rooms used as sleeping accommodation. The mandatory minimum sizes are 6.51 square metres for one person over ten years of age, 10.22 square metres for two persons over ten years, and 4.64 square metres for one child under ten years of age. No part of a room where the ceiling height is less than 1.5 metres may be included in the measurement. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Any room smaller than 4.64 square metres must not be used as sleeping accommodation at all. The landlord must notify the local housing authority of any room in the HMO with a floor area below 4.64 square metres. Communal space elsewhere in the property cannot be counted to compensate for a sleeping room that is below the minimum size. Local authorities may impose higher standards in their licence conditions, but they cannot set standards lower than the statutory minimums. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
A licence holder who knowingly permits the HMO to be occupied by more persons than authorised, or permits a room below the minimum size to be used for sleeping, commits an offence and is liable to an unlimited fine. The local housing authority may alternatively impose a financial penalty of up to £30,000. Where a landlord is found to be in breach at the time of licence renewal, the local authority must give them a period of up to 18 months to become compliant before taking enforcement action. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Waste disposal
All HMO licences granted or renewed since 1 October 2018 must include a condition requiring the licence holder to comply with the local authority's scheme for the storage and disposal of domestic refuse, where such a scheme exists. Failure to comply with this condition is a breach of the licence and a criminal offence. (Source: HMOs and residential property licensing reforms guidance, MHCLG, 2018)
Operating without a licence
Operating an HMO that requires a mandatory licence without holding one is a criminal offence under the Housing Act 2004. Landlords also lose certain rights when unlicensed. Under the Renters Rights Act 2025, control or management of an unlicensed HMO is one of the offences for which a tenant can apply for a rent repayment order, and the maximum repayment period under a rent repayment order has been extended from 12 to 24 months. (Source: Guide to the Renters Rights Act, GOV.UK, November 2025)
The local council is also blocked from granting an HMO a Section 21 notice before the abolition of Section 21, and possession proceedings under the post-Renters Rights Act system require landlords not to be in breach of licensing requirements to use most grounds effectively.
What this means for landlords
If your property is occupied by five or more people from two or more separate households who share basic facilities, it is very likely to require a mandatory HMO licence regardless of how many storeys the building has. You should apply to your local housing authority before operating the property as an HMO. Check whether your local authority also runs an additional licensing or selective licensing scheme that could extend the licensing requirement to smaller HMOs or other properties in your area. Every licensed HMO must meet minimum sleeping room sizes and comply with the waste disposal scheme your local authority operates. Operating without a required licence is a criminal offence and exposes you to a rent repayment order of up to 24 months rent under the Renters Rights Act 2025.
This guide is for informational purposes only and does not constitute legal advice.