Mont. Code Ann. § 30-14-218
30-14-218 Alteration of invoices prohibited
30-14-218 . Alteration of invoices prohibited. It is unlawful for a person to change, alter, substitute, or falsify an invoice if the practice tends to injure a competitor, destroy competition, or mislead a court or the department. Such practice is unfair trade practice and a person resorting to that trade practice is guilty of a misdemeanor and is subject to the penalties provided in 30-14-224 .