Boston Security Deposit Law (2026): Deadlines, Interest & Penalties
Boston law gives landlords a hard deadline: the security deposit must be returned within 30 days of move-out, per Mass. c. 186 § 15B. On top of the deposit itself, the landlord must pay interest of 5% per year on the deposit. Landlords who blow the deadline face treble + fees (state). Enter your deposit details above to check your numbers.
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Boston Deposit Rules at a Glance
| Return deadline | 30 days after move-out State law applies (no separate Boston deposit ordinance) |
|---|---|
| Interest on deposit | 5% per year Held 1+ year |
| Separate account required | Yes |
| Deposit limit | 1 month |
| Penalty for violations | Treble + fees (state) Attorney fees / court costs may also be recoverable |
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Boston Security Deposit FAQ
How long does a landlord have to return a security deposit in Boston?
In Boston, a landlord must return the security deposit within 30 days after the tenancy ends, under Mass. c. 186 § 15B. Note: State law applies (no separate Boston deposit ordinance).
Does my landlord owe me interest on my security deposit in Boston?
Under Mass. c. 186 § 15B, a Boston landlord must pay interest of 5% per year on the deposit. Rate details: 5% per year or actual bank rate.
What is the penalty if a landlord misses the deposit deadline in Boston?
Treble + fees (state). The tenant may also be able to recover attorney fees or court costs. The governing statute is Mass. c. 186 § 15B.
Is there a limit on how much a landlord can charge as a security deposit in Boston?
Yes. In Boston, the security deposit is limited to 1 month.
Does a Boston landlord have to keep my deposit in a separate account?
Yes. Boston law requires landlords to hold security deposits in a separate account, per Mass. c. 186 § 15B.
Are there exceptions to the 30-day deposit deadline in Boston?
Yes — the deadline can vary: State law applies (no separate Boston deposit ordinance). When in doubt, check the statute itself (Mass. c. 186 § 15B) or ask a local tenant-rights organization.
When does the interest requirement apply in Boston?
Interest applies under these conditions: Held 1+ year. See Mass. c. 186 § 15B for the full rule.
What can I do if my landlord won't return my deposit in Boston?
First, send a written demand letter citing Mass. c. 186 § 15B — our free generator creates one with your amounts filled in. If the landlord still doesn't pay, you can usually file in small claims court, where the penalty exposure is treble + fees (state).