Mass. Gen. Laws ch. 171 § 84
The property of the association, the portion of the compensation of any employee deducted or to be deducted under sections eighty-two and eighty-three, the right of an employee to an annuity or pension and all his rights in the funds of the association, shall be exempt from taxation and from the operation of any law relating to insolvency, insurance, retirement systems or pensions and shall not be attached or taken on execution or other process to satisfy any debt or liability of the association, a participating credit union or any employee member of the association. No assignment of any right in or to said funds or of any pension or annuity payable under section eighty-two shall be valid.
Nothing in this section shall be construed to prevent an employee's annuity or pension from being attached, taken on execution, assigned or subject to other process to satisfy a support order under chapter two hundred and eight, two hundred and nine, or two hundred and seventy-three.
Mass. Gen. Laws ch. 171, § 84