Section 81O. No person shall make a subdivision of any land in any city or town in which the subdivision control law is in effect unless he has first submitted to the planning board of such city or town for its approval a plan of such proposed subdivision, showing the lots into which such land is to be divided and the ways already existing or which are to be provided by him for furnishing access to such lots, and the planning board has approved such plan in the manner hereinafter provided. After the approval of a plan the location and width of ways shown thereon shall not be changed unless the plan is amended accordingly as provided in section eighty-one W; but the number, shape and size of the lots shown on a plan so approved may, from time to time, be changed without action by the board, provided every lot so changed still has frontage on a public way or way shown on a plan approved in accordance with the subdivision control law of at least such distance, if any, as is then required by ordinance or by-law of said city or town for erection of a building on such lot, and if no distance is so required, has such frontage of at least twenty feet.
A plan shall be submitted under this section when delivered at a meeting of the board or when sent by registered mail to the planning board. If so mailed, the date of receipt shall be the date of submission of the plan.