310 CMR, § 30.005
Unless otherwise specifically provided by law, 310 CMR 30.000, or any determination issued pursuant to 310 CMR 30.000, any time period prescribed or referred to in 310 CMR 30.000 or in any determination issued pursuant to 310 CMR 30.000 shall begin with the first day following the act which initiates the running of the time period, and shall include every calendar day, including the last day of the time period so computed. If the last day is a Saturday, Sunday, legal holiday, or any other day in which the offices of the Department are closed, the deadline shall run until the end of the next business day. If the time period prescribed or referred to is less than seven days, only days when the offices of the Department are open shall be included in the computation.
310 CMR, § 30.005