Free MA landlord tool
Massachusetts Security Deposit Interest Calculator
Estimate the statutory interest owed on a Massachusetts security deposit under MGL c.186 §15B(3)(b). Updates as you type.
Your deposit
Capped at 5% by statute. Enter your account’s actual rate if lower.
Result
- Days held
- 730
- Effective interest rate
- 5.00%
- Annual interest
- $75.00
- Total interest owed to date
- $150.00
2.00 years
Lesser of 5% or bank rate
Owed each anniversary
Linear accrual through today
How this is calculated
Formula. totalInterest = deposit × min(0.05, bankRate) × daysHeld / 365, applied only when daysHeld ≥ 365.
Statutory basis. MGL c.186 §15B(3)(b) requires interest at 5% per year, or the lesser amount actually paid by the bank, for any security deposit held for one year or longer. Interest accrues from the first day of the tenancy and is paid annually. If the tenancy ends before an anniversary, all accrued interest is owed within 30 days of termination.
Limitations. This calculator estimates only the interest amount. The full compliance picture also requires a separate interest-bearing account in a Massachusetts bank (§15B(3)(a)), a 30-day bank receipt to the tenant, a 10-day statement of condition (§15B(2)(c)), and 30-day return at move-out (§15B(4)).
Tenvale tracks this automatically
Deposits, escrow bank, and annual interest live in one place — so the 30-day clocks and anniversary statements don’t slip.
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