M.G.L. ch. 186 s. 15(B)(2)(a)
“Any lessor or his agent who receives, at or prior to the commencement of a tenancy, rent in advance for the last month of the tenancy from a tenant or prospective tenant shall give to such tenant or prospective tenant at the time of such advance payment a receipt indicating the amount of such rent, the date on which it was received, its intended application as rent for the last month of the tenancy, the name of the person receiving it and, in the case of an agent, the name of the lessor for whom the rent is received, and a description of the rented or leased premises, and a statement indicating that the tenant is entitled to interest on said rent payment at the rate of five per cent per year or other such lesser amount of interest as has been received from the bank where the deposit has been held payable in accordance with the provisions of this clause, and a statement indicating that the tenant should provide the lessor with a forwarding address at the termination of the tenancy indicating where such interest may be given or sent.
Any lessor or his agent who receives said rent in advance for the last month of tenancy shall, beginning with the first day of tenancy, pay interest at the rate of five per cent per year or other such lesser amount of interest as has been received from the bank where the deposit has been held. Such interest shall be paid over to the tenant each year as provided in this clause; provided, however, that in the event that the tenancy is terminated before the anniversary date of such tenancy, the tenant shall receive all accrued interest within thirty days of such termination. Interest shall not accrue for the last month for which rent was paid in advance. At the end of each year of tenancy, such lessor shall give or send to the tenant from whom rent in advance was collected a statement which shall indicate the amount payable by such lessor to the tenant. The lessor shall at the same time give or send to such tenant the interest which is due or shall notify the tenant that he may deduct the interest from the next rental payment of such tenant. If, after thirty days from the end of each year of the tenancy, the tenant has not received said interest due or said notice to deduct the interest from the next rental payment, the tenant may deduct from his next rent payment the interest due.
If the lessor fails to pay any interest to which the tenant is then entitled within thirty days after the termination of the tenancy, the tenant upon proof of the same in an action against the lessor shall be awarded damages in an amount equal to three times the amount of interest to which the tenant is entitled, together with court costs and reasonable attorneys fees. “