A security deposit plus any refundable fees charged by a landlord (for example, a refundable key fee), must total one months rent or less. If however, there is a separate non-refundable, one-time fee for something like having a pet in the premises, that fee does not form part of the security deposit. The security deposit plus any non-refundable fee can equal more than one months rent. It is important to read the lease carefully, or understand any oral agreement you have, so that you can determine what forms part of the security deposit and what does not.
Although a security deposit is usually an amount of money, it can also be an item of property which is equal in value to the monetary amount of the security deposit.