In California, landlords are required to return the security deposit within 21 days after the tenant moves out. If the landlord fails to return the deposit within this time frame, the tenant has two options:

1. Write a letter to the landlord asking for the return of the security deposit. The tenant should keep a copy of the letter for their records.
2. Sue the landlord in small claims court for the return of the security deposit. If the landlord misses the 21-day deadline, they forfeit the right to deduct anything. If they keep the money in bad faith, the tenant can sue for up to three times the amount of the deposit.

It is important to note that landlords can keep a portion of the deposit under certain circumstances, such as unpaid rent or damage to the rental unit, as long as they provide an itemized list of deductions and return any remaining portion of the deposit to the tenant.