From 30 August, [Westminster] landlords will require an HMO (Houses in Multiple Occupation) licence for all house and flat shares with three or more tenants.

Certain buildings converted into self-contained flats will also require a licence if more than a third of the flats [in the building] are rented. We are here to help property managers and landlords who are affected, so please get in touch with us if you have questions about whether you need a licence and how to get one.

Find out if your property requires a licence and apply https://www.westminster.gov.uk/houses-multiple-occupation