Mont. Code Ann. § 15-23-521

The department of revenue may at any time examine the records of any person specified in this part as the records may pertain to the yield of ore or mineral products or deposit in order to verify the statements made by the person. If from the examination or from other information, the department finds any statement or any material part of a statement willfully false or fraudulent, the department must assess in the same manner as provided for in 15-23-503, 15-23-515, 15-23-516, 15-23-517, or 15-23-518.