Mass. Gen. Laws ch. 32 § 65B
A special justice of a district court, including the municipal court of the city of Boston, and a special justice of a juvenile court, who shall be retired under Article LVIII of the Amendments to the Constitution, or a special justice thereof sixty-five years of age or over who shall resign his office after having served as a special justice for at least ten years, shall be entitled to receive a pension or retirement allowance for life at an annual rate equal to three fourths of his average yearly earnings as a special justice for any three years of service in said office, whether consecutive or not, for which such earnings were the highest.
A special judge of probate and insolvency who shall be retired under Article LVIII of the Amendments to the Constitution or a special judge of probate who is sixty-five years of age or over and shall resign his office after having served as a special judge of probate for at least ten years shall be entitled to receive a pension or retirement allowance for life at an annual rate equal to three fourths of his average yearly earnings as special judge of probate during the period of ten years next preceding such retirement or resignation or at an annual rate equal to three fourths of his average yearly earnings as such special judge of probate during the entire period of his service in said office, whichever is the higher rate, but not exceeding in any event an annual rate equal to three fourths of the annual rate of salary of the judge of probate for the county in which he was appointed.
A special justice of a district court, including the municipal court of the city of Boston, and a special justice of a juvenile court or a special judge of probate and insolvency who has served three years or more but who has not served ten years upon his retirement under Article XCVIII of the Amendments to the Constitution at age seventy shall thereupon be entitled to receive a pension or retirement allowance for life at an annual rate equal to ten per cent of three fourths of his average yearly earnings as a special justice for any three years of service in said office, whether consecutive or not, for which such earnings were the highest multiplied by the number of years and fractions thereof consisting of a month or more which he has served in such office or offices.
Said special justices appointed on or after January second, nineteen hundred and seventy-five shall be subject to the requirements of paragraphs (a) and (b) of section sixty-five D provided that any such special justice who, upon resignation or retirement, does not meet retirement requirements set forth in this section shall have returned to him all funds previously withheld and deducted under the provisions of paragraph (b) of said section sixty-five D plus interest, within thirty days of such retirement or resignation.
Pensions under this section shall be paid from the same source and in the same manner as the salaries of the justices of the court from which the special justice was retired or resigned, provided that in the case of special justices subject to the requirements of paragraphs (a) and (b) of section sixty-five D the payment of retirement allowances, annuities, pensions and refunds shall be made pursuant to the provisions of paragraph (h) of said section sixty-five D.
Mass. Gen. Laws ch. 32, § 65B