MA Gen L ch 62c § 33a (2021)
2021 Massachusetts General Laws|Part I - Administration of the Government|Title IX - Taxation|Chapter 62c - Administrative Provisions Relative to State Taxation|Section 33a - United States Postmark; Alternative Private Delivery Service; Date of Payment; Application of Section

Section 33A. If any return, application for abatement of tax, statement or other document required to be filed with the commissioner, or any payment to the commissioner required to be made within a prescribed period or on or before a prescribed date is, after such period or date, delivered by United States mail, or by such alternative private delivery service as the commissioner may by regulation permit, to the office with which such return, application, statement or other document is required to be filed, or to which such payment is required to be made, the date of the United States postmark, or other substantiating date mark permitted by regulation, affixed on the envelope or other appropriate wrapper in which such return, application, statement or other document, or payment, is mailed or delivered shall be deemed to be the date of delivery or the date of payment as the case may be. This provision shall apply only if (A) the postmark date or other substantiating date mark permitted by regulation falls within the prescribed period or on or before the prescribed date (i) for the filing, including any extension granted for such filing, of the return, application, statement or other document or (ii) for making the payment including any extension granted for making such payment; and (B) the return, application, statement or other document, or payment was, within the time prescribed in clause (A), deposited in the mail 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 office with which the return, application, statement or other document is required to be filed, or to which such payment is required to be made.  This section shall apply to any return required to be filed under sections ten or sixteen and any payment required to be made in connection therewith under section thirty-two or under chapters sixty-four A to sixty-four J, inclusive, or chapter one hundred and thirty-eight only if the date of mailing or delivery to such private delivery service falls on or before the second day before such prescribed date and the payment was, on or before such second day, 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 office with which such return or payment is required to be made.  If any petition is, after the period or date prescribed under section 39, delivered by United States mail, or by such alternative private delivery service as the appellate tax board may by rule permit, to the appellate tax board, the date of the United States postmark, or other substantiating date mark permitted by rule of the board, affixed on the envelope or other appropriate wrapper in which such petition is mailed or delivered shall be deemed to be the date of delivery, if such petition 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 board.  As used in this section, ''United States postmark'' means only a postmark made by the United States Post Office.