Mass. Gen. Laws ch. 111 § 127P
Whenever a person has submitted a subdivision plan, or a preliminary subdivision plan which is followed within seven months by a definitive plan, or a plan referred to in section eighty-one P of chapter forty-one, the land shown on such plan shall be governed by provisions of the state environmental code, or of the provisions of local board of health regulations which differ from said code, which are in effect at the time of first submission of said plan. Said provisions shall apply during the time such plan is being processed, including the time required to pursue or await the determination of an appeal relative to said plan. If such plan is approved, or if it is found such approval under the subdivision control law is not required, such provisions shall apply for a period of three years from the date of the endorsement of such approval or from the endorsement that approval under the subdivision control law is not required.
Mass. Gen. Laws ch. 111, § 127P