Massachusetts landlord compliance guide: §15B deposits, interest, late fees

Massachusetts is the strictest deposit jurisdiction in New England: MGL c.186 §15B carries strict-liability treble damages. Question by question:

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

One month's rent (MGL c.186 §15B). Stonerow enforces the cap at lease save — the highest-risk mistake in MA landlording is stopped at entry.

What can a Massachusetts landlord collect at move-in?

§15B limits move-in monies to: first month's rent, last month's rent, a security deposit up to one month, and a lock/key fee. Application fees charged by landlords are effectively barred.

Do Massachusetts landlords have to pay interest on deposits?

Yes — 5% or the actual bank rate on deposits held a year or more. Last month's rent collected in advance also earns interest. Stonerow calculates the MA accrual per lease — on demand on Core, automatically on Standard.

When can a Massachusetts landlord charge a late fee?

Not until rent is 30 days overdue (§15B). Stonerow's late-fee engine respects the 30-day grace on every assessment — a premature fee never posts.

Why do deposit mistakes cost triple in Massachusetts?

Certain §15B violations carry treble (3×) damages plus interest, costs, and attorney's fees — strict liability, meaning intent doesn't matter. The 30-day return window, itemization, and receipt formalities are where landlords get caught. An append-only ledger, tracked interest, and a statute-cited itemization PDF are Stonerow's answer — see the guide.

General information, not legal advice. Statutes change — verify current law with counsel. Product view: Stonerow for Massachusetts landlords.

Why Massachusetts is the strictest deposit jurisdiction in the region

MGL c.186 s.15B is strict liability with treble damages: intent does not matter, and certain violations cost three times the deposit plus interest, costs, and attorney's fees. Massachusetts practitioners routinely advise small landlords not to take a security deposit at all rather than risk the formalities — which tells you how sharp the edge is. Stonerow's position is narrower and more useful: if you are going to hold one, the cap should be impossible to exceed by accident and the interest should accrue without anyone remembering to do it.

The formalities that actually catch people

The one-month cap is the headline, but the failures cluster in the details: collecting more than the permitted move-in monies, missing the interest obligation on deposits held a year or more, charging a late fee before rent is thirty days overdue, and missing the return window at move-out. Each is individually small and each is independently actionable. The system enforces the cap at lease save, respects the thirty-day grace on every late-fee assessment whether you run it by hand or on schedule, and tracks the interest per lease so the number exists when you need it.

Build the paper trail before you need it

A Massachusetts deposit dispute is won or lost on documentation. Move-in and move-out inspections with photographs establish condition. The append-only ledger establishes what was owed and when. The statute-cited itemization statement establishes what you deducted and why. None of these are difficult individually; the reason landlords lose is that they are assembled after the dispute starts rather than accumulated during the tenancy. This is general information, not legal advice — have your lease and your process reviewed by a Massachusetts attorney.