Mass. Gen. Laws ch. 80 § 10
A person who is aggrieved by the refusal of a board of officers of a city, town or district to abate an assessment may, instead of pursuing the remedy provided by section seven, appeal within the time limited therein to the county commissioners of the county in which the land assessed is situated. The person so appealing shall, within ten days after the filing of said appeal, give written notice thereof to such city, town or district. Such notice may be given by mailing a copy of the appeal by registered mail, postage prepaid, to the board which made the assessment or to the clerk of such city, town or district. The county commissioners shall hear the parties, and shall have the same powers and duties with respect to the abatement of such assessment as the board by which it was assessed, and may make an order as to costs. The decision of the county commissioners shall be final.
Mass. Gen. Laws ch. 80, § 10