Mont. Code Ann. § 35-17-203

At any time after filing, the articles of incorporation may be amended. Any amendment of the articles of incorporation must be approved by a majority of the directors and then adopted by vote of a majority of those members voting at any regular meeting of the association or at a special meeting called for the purpose of amending the articles, unless the articles require approval by a larger number of directors or members. A statement setting forth the amendment must be executed and attested to on behalf of the association by its appropriate officers. The statement must be filed in the office of the secretary of state who shall issue a certificate of amendment of the articles of incorporation. A certified copy of the certificate of amendment must be filed in the office of the county clerk for the county in which the principal office of the association is located.