Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 158, § 16

If a corporation which has a franchise in and the use of the public streets of a town for the supply and distribution of gas, water, electric light or power, or for the maintenance of communication by wire or otherwise, holds for a longer period than six months money which is collected in advance from its customers to guarantee it against loss of charges or tolls, it shall pay annually upon said guaranty fund interest, at a rate fixed from time to time by the department of public utilities or the department of telecommunications and cable, to the depositors thereof which shall be applied to the payment of charges and tolls by said depositors. The annual return required of such corporations by section thirty-seven shall include a true statement of all money, and of the value of any collateral, so held as a guaranty for the payment of charges or tolls, specifying the amount so deposited by the inhabitants of each town. If such corporation fails or neglects to make such return or fails, neglects or refuses to pay such interest it shall be punished by a fine of not less than one hundred nor more than five hundred dollars.