Mass. Gen. Laws ch. 32 § 81B
Any permanent member of a fire department retired under the provisions of subdivision (a) of section eighty-one A shall receive an annual pension equal to seventy-two per cent of the highest annual rate of compensation or salary received by him while holding the grade held by him at the time of his retirement. The pension of any call fireman or substitute call fireman retired under the provisions of said paragraph (a) shall be the same as that of a permanent member of the first grade of the same department in which he served, or, if there be no grades, his compensation shall be that of a permanent member of the department performing duties like those which he performed.
Any permanent member of a fire department retired under the provisions of subdivision (b), (c) or (d) of said section eighty-one A shall receive an annual pension equal to sixty per cent of the highest annual rate of compensation received by him while holding the grade held by him at the time of his retirement if he has completed twenty years of service, and an additional amount equal to one per cent of said annual compensation for each year of service after the first twenty; provided, that the total amount of such pension shall in no case exceed seventy-two per cent of said annual compensation.
Mass. Gen. Laws ch. 32, § 81B