Can a landlord ask for information about flatmates even though they are not on the tenancy agreement?

No, generally a tenant can have flatmates live with them. A tenancy agreement doesn't usually require the landlord’s consent to a room being lived in by a flatmate.

But if the tenancy agreement limits the maximum number of persons who can live in the property, then it may be a condition of the tenancy to also include being informed of that person’s identity before the landlord will agree to increasing the maximum number of persons allowed to live there.

Otherwise, the landlord’s relationship is with the tenants named in the tenancy agreement and who are responsible for the rent and the state of the property being rented. If there is no maximum number of persons written on the tenancy agreement or if the flatmate would not exceed the maximum allowed, then the information of flatmates would not be relevant to the landlord. The tenant is responsible for the tenancy and this includes any persons they have living with them.

Flatmates who are not tenants are not covered by the Residential Tenancies Act. Their rights depend on their agreement with the named tenant.

For more information, see our guidance for landlords and tenants.