Mont. Code Ann. § 13-1-503
13-1-503 Deadlines for absentee and mail ballots
13-1-503 . Deadlines for absentee and mail ballots. (1) Pursuant to 13-13-205 , ballots for a special purpose district election must be available for absentee voting at least 20 days before election day if the election is not conducted by mail.
(2) Pursuant to 13-19-207 , ballots must be mailed no sooner than the 20th day and no later than the 15th day before election day if the election is conducted by mail.