How much can a landlord charge for a security deposit in Massachusetts?

One month's rent (separate from first month, last month and lock-and-key cost) (M.G.L. c. 186, 15B).

How long does a landlord have to return a security deposit in Massachusetts?

Within 30 days after the tenancy ends (M.G.L. c. 186, 15B).

Massachusetts security deposit law

The state rules a landlord in Massachusetts has to follow for a residential security deposit, from M.G.L. c. 186, 15B.

Maximum deposit: One month's rent (separate from first month, last month and lock-and-key cost).
Deadline to return it: Within 30 days after the tenancy ends.
Itemized deductions: Sworn, itemized list of damages with written estimates, bills or receipts, sent within 30 days.
Interest on the deposit: Yes: 5% a year, or the lower rate the bank actually paid, paid yearly; deposit must be in a separate Massachusetts bank account.
Penalty for wrongful withholding: Three times the deposit owed plus 5% interest, court costs and attorney fees if the deposit, receipt or bank-account rules are broken.

Before you keep any part of a deposit

Compare the unit with the move-in inspection and photos. Normal wear and tear is generally not chargeable.
Keep receipts or written estimates for every deduction.
Send the return or the itemized list within the deadline above, to the tenant's forwarding address, and keep proof of mailing.

Working out the last month's rent? The prorated rent calculator does the partial-month math.

Source

Verification status: verified summary. Research date: November 5, 2026. Statute: M.G.L. c. 186, 15B. Source: malegislature.gov.

General information, not legal advice. Cities and counties can add stricter rules, and laws change. Check the current statute or a local attorney before you act.

Other states: Maryland · Minnesota · all states

Last updated November 5, 2026.