Mnemonic: dwelling_hmo_unrelated
Applicability: Dwelling
Type: Derived variable


A dwelling where unrelated tenants rent their home from a private landlord is a HMO, if both of the following apply:

  • at least three unrelated individuals live there, forming more than one household
  • toilet, bathroom or kitchen facilities are shared with other tenants

A small HMO is shared by 3 or 4 unrelated tenants. A large HMO is shared by 5 or more unrelated tenants.


Total number of categories: 3

Code Name
1 Is a small HMO
2 Is a large HMO
-8 Does not apply*

*Dwellings that are not houses in multiple occupation (HMOs), or households that are not in HMOs.

Quality information

Improvements to the Census address frame allowed us to accurately list multiple household spaces within the same building. This means the data are more often counted as distinct households within separate dwellings reflecting living arrangements.

Read more in our housing quality information for Census 2021 methodology.


Read about how we developed and tested the questions for Census 2021.

Comparability with the 2011 Census

Not comparable

This variable is new for Census 2021 and there is no comparability with the 2011 Census.

What does not comparable mean?

A variable that is not comparable means that it cannot be compared with a variable from the 2011 Census.

England, Wales, Northern Ireland and Scotland comparisons

Not comparable

This variable is not comparable as the data is not available for all countries.

What does not comparable mean?

A variable that is not comparable means that it cannot be compared for England, Wales, Scotland and Northern Ireland.

Find out more about variables produced for Census 2021 in Northern Ireland and Census 2022 in Scotland.

Households of multiple occupancy (HMO) in Wales

The Census 2021 definition of households in multiple occupancy (HMO) is "a dwelling where at least three unrelated tenants rent their home from a private landlord".

The Welsh Government collects and publishes data on HMOs by local authority area in Wales, on an annual basis. In this collection, the definition differs to the Census 2021 definition. HMOs are defined as "a building or part of a building occupied by persons forming at least two households sharing at least one basic amenity". See Sections 254 to 259 of the Housing Act 2004 for more information.

For this reason, counts of HMOs published in Census 2021 and by the Welsh Government are not comparable.

Census 2021 data that uses this variable