At the beginning of the tenancy, you may legally require a tenant to pay the last month’s rent in advance and a security deposit in an amount no greater than the equivalent of one month’s rent. If you collect them, you must, among other things, give proper receipts, pay interest on an annual basis, and in the case of the security deposit, put the money in a separate interest-bearing account in a bank located in Massachusetts. It is important that you comply with the strict requirements of the security deposit law.