Deposit handling for sublets, done fairly
State the deposit amount, purpose, receipt date, return process, and permitted deductions in the written sublease. Give a receipt and take move-in photos. Keep the funds and records organized so they are not confused with rent or your deposit under the primary lease.
At move-out, inspect the room, compare it with the original condition record, and provide the required accounting under applicable law. Do not call a charge “nonrefundable” simply to avoid a later explanation.
If the arrangement is in San Francisco, check current state deposit rules and local interest requirements. A short sublet is still a real financial transaction.
Source: SF Rent Board security-deposit guide.