Mass. Gen. Laws ch. 59 § 59
A person upon whom a tax has been assessed or the personal representative of the estate of such person or the personal representative or trustee under the will of such person, if aggrieved by such tax, may, except as hereinafter otherwise provided, on or before the last day for payment, without incurring interest in accordance with the provisions of section fifty-seven or section fifty-seven C, of the first installment of the actual tax bill issued upon the establishment of the tax rate for the fiscal year to which the tax relates, apply in writing to the assessors, on a form approved by the commissioner, for an abatement thereof, and if they find him taxed at more than his just proportion or upon an improper classification, or upon an assessment of any of his property in excess of its fair cash value, they shall make a reasonable abatement; provided, however, that a person aggrieved by a tax assessed upon him under section seventy-five or section seventy-six or reassessed upon him under section seventy-seven may apply for such abatement at any time within three months after the bill or notice of such assessment or reassessment is first sent to him. A tenant of real estate paying rent therefor and under obligation to pay more than one-half of the taxes thereon may apply for such abatement. If a person other than the person to whom a tax on real estate is assessed is the owner thereof, or has an interest therein, or is in possession thereof, and pays the tax, he may thereafter prosecute in his own name any application, appeal or action provided by law for the abatement or recovery of such tax, which after the payment thereof shall be deemed for the purposes of such application, appeal or action, to have been assessed to the person so paying the same. The holder of a mortgage on real estate who has paid not less than 1/2 of the tax thereon may, during the last 10 days of the abatement period of the year to which the tax relates, apply in the manner above set forth for an abatement of such tax provided the person assessed has not previously applied for abatement of such tax, and thereupon the right of the person assessed to apply shall cease and determine. The holder of a mortgage so applying for abatement may thereafter prosecute any appeal or action provided by law for the abatement or recovery of such tax in the same manner and subject to the same conditions as a person aggrieved by a tax assessed upon him.
Notwithstanding any other provision of this section, a person who acquires title to real estate after January first in any year, shall for the purposes of this section be treated as a person upon whom a tax has been assessed.
An application for exemption under clause Seventeenth, Seventeenth C, Seventeenth C1/2, Seventeenth D, Eighteenth, Twenty-second, Twenty-second A, Twenty-second B, Twenty-second C, Twenty-second D, Twenty-second E, Twenty-second F, Thirty-seventh, Thirty-seventh A, Forty-first, Forty-first B, Forty-first C, Forty-first C1/2, Forty-second, Forty-third, Fifty-second, Fifty-third, Fifty-sixth and Fifty-seventh of section 5 may be made on or before April 1 of the year to which the tax relates, or within 3 months after the bill or notice of assessment was sent, whichever is later.
If any application for abatement of tax is, after the period or date prescribed by this section, delivered by United States mail, or by such alternative private delivery service as the commissioner of revenue may by regulation permit, to the assessors, the date of the United States postmark, or other substantiating date mark permitted by regulation of the commissioner of revenue, affixed on the envelope or other appropriate wrapper in which such application is mailed or delivered shall be deemed to be the date of delivery, if such application was mailed in the United States in an envelope or other appropriate wrapper, first class postage prepaid, or delivered to such alternative private delivery service, properly addressed to the assessors. As used in this section, ''United States postmark'' shall mean only a postmark made by the United States post office.
Notwithstanding the foregoing provisions, if the last day for making an application for abatement of tax falls on a Saturday, Sunday, legal holiday or day on which municipal offices are closed as authorized by charter, by-law, ordinance or otherwise for a weather-related or public safety emergency, the application may be made on the next day that a municipal office is open.
Mass. Gen. Laws ch. 59, § 59