The law on changing roommates is highly complicated and it is recommended that you consult an attorney before getting new roommates, especially if you live in a rent-controlled jurisdiction. An analysis of a tenant’s rights in such a situation prospectively involves contract law, State law and local laws, rules and regulations.
Most rental agreements allow for subleasing or assignment of a rental agreement with the written approval of the landlord. You need to read your rental agreement prior to attempting to rent your unit to a new roommate.
Using San Francisco as an example, if there is an original tenant who is a party to a rental agreement and continues to reside in the unit, the rent cannot be increased by more than is annually allowed under the S.F. Rent Ordinance. If new roommates (subtenants) pay rent directly to the landlord, they usually will establish a tenancy which will mean that should all original tenants vacate, they would still be entitled to pay rent at the rent-controlled rate. However, if the landlord serves a S.F. Regulation 6.14 Notice within a reasonable time (usually construed as a few months) of learning that there is a new subtenant, then after the original tenants vacate, rent may be increased to market rent on the subtenants.
If the rental agreement allows for subtenants or assignment, a landlord cannot unreasonably withhold consent for a new roommate if there is not an increase in the number of tenants residing in the unit. For example, if there are 3 bedrooms in your rental unit and a bedroom becomes vacant, then you have a right to get a new roommate to replace the tenant who recently vacated. A landlord can withhold consent of a prospective roommate for bad credit or a bad reference. If you believe that your landlord is unreasonably withholding consent for a new roommate, you may contact the S.F. Human Rights Commission if you live in San Francisco or a tenant attorney.
This is a very general overview and it should not be used as legal advise. If you have questions you can contact us for a free consultation.