Mass. Gen. Laws ch. 32 § 92
Any pledge, mortgage, sale, assignment or transfer of any right, claim or interest in any pension, annuity or retirement allowance from the commonwealth or any county, city, or town shall be void, except such assignment made in writing by a retired person authorizing the retiring authority to withhold each month such amount as he may designate for the payment of subscriber premiums applicable to any hospitalization, medical or surgical insurance in effect with a non-profit hospital and medical service corporation or insurance company at the time of his retirement. Whoever is a party to such pledge, mortgage, sale, assignment or transfer of any right, claim or interest in any pension, annuity or retirement allowance or pension certificate from the commonwealth or any county, city or town, or holds the same as collateral security for any debt or promise, or upon any pretext of such security or promise, shall be punished by a fine of not more than one hundred dollars. If a person receiving a pension, annuity or retirement allowance becomes a charge upon the commonwealth, or any county, city or town thereof, the expense incurred by the commonwealth, or any such county, city or town, for his maintenance and support shall, unless otherwise paid, be deducted from such pension, annuity or retirement allowance as it becomes due and payable, and the amount of such deduction shall thereupon be paid to the department, board, commission or officer by whom or under whose authority such expense was incurred.
Mass. Gen. Laws ch. 32, § 92