Mass. Gen. Laws ch. 170 § 26
The property of the benefit association shall be exempt from taxation and from the operation of any law relating to insolvency, and shall not be attached or taken on execution or other process to satisfy any debt or liability of the benefit association, a participating bank, or any employee member of the benefit association. No assignment of any right in or to said funds or of any pension or annuity payable under section 24 shall be valid, except that deferred annuity contracts purchased by a participating bank on account of past service of eligible employees may be assigned to such bank prior to actual retirement.
Nothing in this section shall 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 208, 209 or 273.
Mass. Gen. Laws ch. 170, § 26