How to protect yourself as a master tenant
First, make sure the primary lease permits the arrangement and seek written landlord approval where required. Screen subtenants fairly, explain the true lease status, and use a written agreement that matches the space and term you are offering.
Keep a ledger for rent, utilities, deposits, repairs, notices, and keys. Give receipts and preserve messages. Set reasonable household rules before move-in, not after a conflict.
If a subtenant violates an agreement or will not leave, do not improvise. As a master tenant you may have landlord-like duties, and self-help eviction can be unlawful. Use the Rent Board or a qualified housing lawyer to understand the correct process.
Source: SF Rent Board guidance.