First, there are many rules about the amount that can be collected. The major problems arise at check-out time. Such as agreeing what is normal wear and tear, and slow deposit return by landlords.
Example: The rent is $3,000 a month and the apartment is unfurnished. You all probably know that the maximum security deposit that can be required for an unfurnished unit is the value of two months of rent. That would be $6,000.00. For a furnished apartment you can collect three months of rent.
This is true no matter what you call the deposit. Key, pet security etc. Added together the total can not go over the requirements discussed above. And no fee can be designated non-refundable. Never call it last month’s rent because as a landlord, you would have no money for unpaid rent or damages when the tenants move out.
After deducting damages, unpaid rent, wear and tear, and other legal deductions, the landlord must pay the balance to the tenant within 21 days of move out. So work fast.
Obviously, it is a good idea to take photos when the tenant moves in and photos when they move out. Judges in small claim courts love photos, because they give them something to look at instead of looking at the combatants. Also, there are requirements for inspections when tenants move. The California Association of Realtors and an Apartment Association have the forms to complete the inspections.
And hope they do not leave furniture and other items behind. If they do, find someone to advise you on what to do. Simply, you have to inventory and hold for a proper period of time.
Good Luck Landlords. I know your pain.