Last Month's Rent Interest Calculator — United States

Only in some states and cities. The majority of states do not require it. Jurisdictions that do include New Jersey, Connecticut, Massachusetts, Minnesota, and cities such as Chicago and New York (for larger buildings). The required rate is usually tied to a bank or savings rate published annually.

Multiply the deposit by the required rate for each year held. Rates are small — often well under 1% — and are set annually. Massachusetts nominally requires 5% (or the lower rate the bank actually pays). Chicago publishes a rate near 0.01% in recent years. Always use the current published figure.

Timing varies. Some jurisdictions require the landlord to pay or credit interest annually; others require it only at the end of the tenancy with the deposit refund. Chicago and New Jersey have strict rules and penalties — a landlord who fails to pay can owe the tenant multiple times the deposit.

In strict-deposit cities the penalties are severe. Chicago's RLTO can entitle the tenant to two months' rent plus the withheld interest and attorney fees. New Jersey allows the tenant to apply the deposit to rent. Landlords in these areas should track and pay interest carefully.