Mont. Code § 18-7-204
No claim against the state for legal advertising or any of the publications covered by this part shall be allowed unless there is attached to said claim the certification of the publisher or printer (in the case of corporations or quasi-corporations by the business or advertising manager thereof) properly executed, setting forth that the price or rate charged the state of Montana for the publication for which claim is made is not in excess of the minimum rate charged any other advertiser for publication or advertisement set in the same sized type and published for the same number of insertions. It is hereby declared to be unlawful to make any claim against or to charge or attempt to charge the state of Montana for any publication in excess of the minimum going rate charged any other advertiser for the same publication set in the same sized type and published for the same number of insertions.
§ 18-7-204, MCA