Mass. Gen. Laws ch. 152 § 59
The state treasurer shall hold any deposit made under section fifty-seven in trust for the payment of claims for benefits under this chapter, including claims accruing after the deposit was made, and he shall make such payments upon the written request and under the direction of the department, or he may, if the company so requests in writing, transfer from time to time to a trustee appointed by the company and approved by the department, any part of any such deposit made with him, reasonably necessary for the prompt payment of said benefits, and the trustee shall make such payments in accordance with the written directions of the department.
The state treasurer shall keep a separate account with the company of the amount so received, the amount of interest earned thereon and the payments made. If the amount deposited proves to be larger than required, portions thereof may, from time to time, be refunded to the company by the state treasurer or by such trustee, if any, subject to the written approval of the commissioner of insurance and the department. If any balance remains after the payment of all benefits due to claimants under this chapter, the state treasurer or such trustee, if any, shall return the balance to the company upon written notice from the department that there is no likelihood of further payments becoming due on account of such claims.
Mass. Gen. Laws ch. 152, § 59