Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 59, § 65D

If a person having an interest in a parcel of real estate files with the appellate tax board within the time prescribed by section sixty-five an appeal with respect to a tax assessed thereon, after having paid on account of such tax the amount prescribed by section sixty-five B but by reason of mistake not having paid the amount required under section sixty-five, said board, upon motion filed within two months after the discovery of such mistake, may grant upon such appeal such abatement, if any, as the assessors by agreement with such person may determine.