831 CMR, § 1.36
In computing any period of time prescribed or allowed by these Rules, the day of the act, event, or default after which the designated period of time begins to run shall not be included. The last day of the period so computed shall be included, unless it is a Saturday, a Sunday, or a legal holiday, in which event the period runs until the end of the next day which is not a Saturday, a Sunday, or a legal holiday. When the period of time prescribed or allowed is less than seven days, intermediate Saturdays, Sundays, and legal holidays shall be excluded in the computation. As used in this rule, "legal holiday" includes those days specified in M.G.L. c. 4, § 7 and any other day appointed as a holiday by the President or the Congress of the United States or designated by the laws of the Commonwealth.
831 CMR, § 1.36