Mont. Code Ann. § 27-16-503

Upon arrest of the defendant by the sheriff or upon the defendant's delivery to the sheriff by the bail or upon the defendant's own surrender, the bail must be exonerated if the arrest, delivery, or surrender take place before the expiration of 10 days after judgment. However, if the arrest, delivery, or surrender is not made within 10 days after the judgment, the bail must be finally charged on their undertaking and be bound to pay the amount of the judgment within 10 days after the judgment.