Mass. Gen. Laws ch. 59 § 5K
In any city or town which accepts the provisions of this section, the board of selectmen of a town or in a municipality having a town council form of government, the town council or the mayor with the approval of the city council in a city may establish a program to allow persons over the age of 60 to volunteer to provide services to such city or town. In exchange for such volunteer services, the city or town shall reduce the real property tax obligations of such person over the age of 60 on his tax bills and any reduction so provided shall be in addition to any exemption or abatement to which any such person is otherwise entitled and no such person shall receive a rate of, or be credited with, more than the current minimum wage of the commonwealth per hour for services provided pursuant to such reduction nor shall the reduction of the real property tax bill exceed $2,000 in a given tax year. It shall be the responsibility of the city or town to maintain a record for each taxpayer including, but not limited to, the number of hours of service and the total amount by which the real property tax has been reduced and to provide a copy of such record to the assessor in order that the actual tax bill reflect the reduced rate. A copy of such record shall also be provided to the taxpayer prior to the issuance of the actual tax bill. Such cities and towns shall have the power to create local rules and procedures for implementing this section in any way consistent with the intent of this section.
In no instance shall the amount by which a person's property tax liability is reduced in exchange for the provision of services be considered income, wages, or employment for purposes of taxation as provided in chapter 62, for the purposes of withholding taxes as provided in chapter 62B, for the purposes of workers' compensation as provided in chapter 152 or any other applicable provisions of the General Laws, but such person while providing such services shall be considered a public employee for the purposes of chapter 258, but such services shall be deemed employment for the purposes of unemployment insurance as provided in chapter 151A.
A city or town, by vote of its legislative body, subject to its charter, may adjust the exemption in this clause by: (1) allowing an approved representative, for persons physically unable, to provide such services to the city or town; or (2) allowing the maximum reduction of the real property tax bill to be based on 125 volunteer service hours in a given tax year, rather than $2,000.
Mass. Gen. Laws ch. 59, § 5K