Massachusetts Security Deposit Law (2026): Deadlines, Interest & Penalties
Wondering when your Massachusetts security deposit is due back? The statute — Mass. Gen. Laws c. 186 § 15B — sets the return window at 30 days from the end of your tenancy, and the landlord must pay interest of 5% per year on the deposit. If the money doesn't arrive on time, the exposure for the landlord is treble damages + interest + costs + attorney fees. The calculator above works out your deadline, interest, and penalty figures automatically.
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Massachusetts Deposit Rules at a Glance
| Return deadline | 30 days after move-out Standard deadline applies. |
|---|---|
| Interest on deposit | 5% per year Held 1+ year |
| Separate account required | Yes |
| Deposit limit | 1 month's rent |
| Penalty for violations | Treble damages + interest + costs + attorney fees Attorney fees / court costs may also be recoverable |
Massachusetts Security Deposit FAQ
How long does a landlord have to return a security deposit in Massachusetts?
In Massachusetts, a landlord must return the security deposit within 30 days after the tenancy ends, under Mass. Gen. Laws c. 186 § 15B. Note: Standard deadline applies..
Does my landlord owe me interest on my security deposit in Massachusetts?
Under Mass. Gen. Laws c. 186 § 15B, a Massachusetts 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 Massachusetts?
Treble damages + interest + costs + attorney fees. The tenant may also be able to recover attorney fees or court costs. The governing statute is Mass. Gen. Laws c. 186 § 15B.
Is there a limit on how much a landlord can charge as a security deposit in Massachusetts?
Yes. In Massachusetts, the security deposit is limited to 1 month's rent.
Does a Massachusetts landlord have to keep my deposit in a separate account?
Yes. Massachusetts law requires landlords to hold security deposits in a separate account, per Mass. Gen. Laws c. 186 § 15B.
Are there exceptions to the 30-day deposit deadline in Massachusetts?
Yes — the deadline can vary: Standard deadline applies.. When in doubt, check the statute itself (Mass. Gen. Laws c. 186 § 15B) or ask a local tenant-rights organization.
When does the interest requirement apply in Massachusetts?
Interest applies under these conditions: Held 1+ year. See Mass. Gen. Laws c. 186 § 15B for the full rule.
What can I do if my landlord won't return my deposit in Massachusetts?
First, send a written demand letter citing Mass. Gen. Laws 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 damages + interest + costs + attorney fees.