What Is an HMO in Westminster? How to Tell if Your Property Qualifies

Your flat in Maida Vale has two tenants on the lease. A friend asks to move into the spare room. That third person could quietly flip your property from a standard rental into a House in Multiple Occupation — and in Westminster, that means a different licence, higher fees and a set of conditions that didn't apply yesterday.

The Statutory HMO Definition

Under Part 2 of the Housing Act 2004, a property is an HMO when it is occupied by three or more people who form two or more separate households and share at least one amenity — a kitchen, bathroom or toilet. "Household" has a specific legal meaning: members of the same family count as one household (married couples, cohabiting partners, parents and children, siblings), while unrelated individuals each form a separate household.

The test is about who actually lives there, not what the tenancy agreement says. Two friends on a joint tenancy are two households. A couple and an unrelated lodger are two households (the couple is one, the lodger is another); with three occupants sharing basic amenities, that arrangement is an HMO.

How Westminster Applies the Thresholds

Westminster runs three licensing schemes, and the occupancy numbers determine which one you need:

• 1–2 occupants (any number of households): If your property sits in one of the 15 wards covered by selective licensing, you need a selective licence. Properties in the three exempt wards (Pimlico South, St James's and Vincent Square) need no licence at all under this threshold.
• 3–4 occupants forming 2 or more households: This is an HMO under Westminster's additional licensing scheme, which covers all 18 wards borough-wide. The selective licence does not apply because the additional scheme takes priority.
• 5 or more occupants forming 2 or more households: This triggers mandatory HMO licensing — a national requirement that applies across every ward in every council in England.

The key detail people miss: the additional HMO scheme applies borough-wide, including those three wards excluded from selective licensing. A flat in Vincent Square with three unrelated tenants still needs an additional HMO licence.

Common Scenarios That Catch Landlords Out

The couple plus one. A married couple and one friend rent a flat together. Three people, two households — that property is an HMO. If it is in Westminster, it needs an additional HMO licence.

The company let. Letting to a corporate tenant does not create an automatic exemption. If the employees living there form two or more households and number three or more, the property is an HMO regardless of who signed the lease.

The resident landlord. If you live in the property and let rooms to no more than two lodgers, you are exempt from HMO licensing. Take on a third lodger and the exemption vanishes — the property becomes an HMO.

The growing family. In a rental where a couple are tenants rather than resident landlords, their adult child moves back home and they also share with an unrelated lodger. The family (couple plus child) is one household, the lodger is another — two households, four people. That arrangement needs an additional HMO licence.

Converted Flats and Section 257

A building that was converted into self-contained flats without complying with the 1991 Building Regulations, and where fewer than two-thirds of the flats are owner-occupied, may itself meet the HMO definition under Section 257 of the Housing Act 2004. Westminster has explicitly excluded Section 257 converted blocks from its additional HMO scheme. But the individual flats inside such a block are still subject to licensing based on their own internal occupancy: a flat let to three unrelated people in a Section 257 block still needs an additional HMO licence for that flat.

Why the Definition Matters for Fees

Getting the classification wrong is expensive. A selective licence in Westminster costs £995 (split into a £543 Part A and a £452 Part B). An additional HMO licence costs £1,540 (£855 + £685), and mandatory HMO licensing costs the same. Part A is non-refundable — if you apply for the wrong scheme, you lose the processing fee and start again.

Beyond fees, letting an unlicensed property exposes you to civil penalties of up to £40,000 per offence and tenant rent repayment orders covering up to 24 months of rent paid during the unlicensed period.

Checking Your Property

The safest approach is a three-step check: count the people who actually live in the property, work out how many separate households they form, then verify which ward the property sits in using Westminster's GIS address lookup tool. The ward determines whether selective licensing applies; the household count determines whether additional or mandatory HMO licensing applies instead.

Our Westminster Landlord Licensing guide walks through every step of the decision, from the ward boundary check through to the application and fee calculation for each scheme — with a printable worksheet to record the result.

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