Mont. Code Ann. § 1-1-307
1-1-307 Postponement of day appointed for an action when it falls on a holiday or Saturday
1-1-307 . Postponement of day appointed for an action when it falls on a holiday or Saturday. Whenever any act of a secular nature, other than a work of necessity or mercy, is appointed by law or contract to be performed upon a particular day, which day falls upon a holiday or a Saturday, such act may be performed upon the next business day with the same effect as if it had been performed upon the day appointed.