Master tenant responsibilities you shouldn't take lightly
A master tenant is generally the tenant with the direct lease to the owner. If they rent space to another person, they may have responsibilities toward that subtenant while still owing obligations to the owner.
Before taking that role, confirm the lease permits the arrangement and obtain any required consent. Use a written sublease that identifies rent, deposit, utilities, term, room, house rules, notices, and how repairs are reported. Keep rent and deposit records separate and accurate.
Do not use self-help to remove a subtenant—changing locks, shutting off utilities, or throwing out property can create serious legal problems. Get advice before acting on a dispute.
Sources: SF Rent Board guidance, California Civil Code.