Mass. Gen. Laws ch. 138, § 25B
(d) Each such schedule shall be filed on or before the tenth day of the month on a date to be fixed by the commission, and the prices and discounts therein set forth shall become effective on the first day of the calendar month following the filing thereof and shall be in effect for such calendar month and from month to month thereafter until such time as a new or amended schedule is filed and becomes effective hereunder. No brand of alcoholic beverages shall be sold to any wholesaler except at the price then in effect unless written permission of the commission is granted for good cause shown and for reasons not inconsistent with the purpose of this chapter.
All schedules filed pursuant to this section shall be subject to public inspection and shall not be considered confidential.