Security deposits are a must in rental property management. But there are rules on how much of a deposit may be requested, what it can be used for, and how any unused portion must be returned to the tenant. Where I practice in California the landlord may obtain from the tenant, at the inception of the tenancy, a security deposit of up to two months' rent for unfurnished premises and up to three months' rent for furnished premises. The security deposit may be in addition to the first month's rent charged in advance.
The landlord must hold the security deposit for the benefit of the tenant. The landlord may only deduct from the security deposit for unpaid rent, damage to the premises except for ordinary wear and tear, and cleaning the premises so as to return it to the same condition that it was in at the start of the tenancy.
Where one party terminates the tenancy (other than for breach of the lease or failure to pay rent), the landlord must give the tenant, within a reasonable time after notice of termination, written notice of the tenant's right to an inspection and advance notice of deficiencies that could result in deductions from the deposit. The tenant must then request the inspection. If the tenant does so, the landlord must inspect and give the tenant an itemized statement of problems with the property's condition so that the tenant has the opportunity to correct them prior to move-out. The parties then typically schedule a final walk-through where the landlord can check to see if the tenant has corrected the problems.
The landlord has 21 calendar days after the tenant vacates to give the tenant, by personal delivery or by first-class mail, an itemized statement showing all deductions from the security deposit and return to the tenant any unused portion of the deposit. For all deductions, the landlord must also provide supporting documentation such as invoices, bills, receipts, etc. If the landlord fails to account for the security deposit to the tenant, the tenant may sue for return of the deposit. If the tenant can show that the landlord's retention of the deposit was in bad faith, the court may award the tenant a statutory penalty of up to two times the amount of the deposit.