Mont. Code Ann. § 50-60-509

A person who commences any work for which a permit is required without first obtaining a permit shall, if subsequently allowed to obtain a permit, pay double the permit fee for the work, except that this provision does not apply to emergency work when it is proved to the satisfaction of the department of labor and industry or its authorized representative that the work was urgently necessary and that it was not practical to obtain a permit before the commencement of the work. In all emergency cases, a permit must be obtained as soon as it is practical to do so, and if there is unreasonable delay in applying for the permit, a double fee must be charged.