Mont. Code § 33-2-127
The certificate of authority, producers' appointments and licenses, policy forms, rates, and other items that the commissioner allows that are in existence at the time an insurer admitted to transact insurance in this state transfers its corporate domicile to this or any other state continue in effect upon transfer if the insurer remains qualified to transact insurance in this state. All rates and outstanding policies of a transferring insurer remain in effect, and policies need not be endorsed as to the new name of the company or its domicile unless required by the commissioner. A transferring insurer either shall file new policy forms for use in this state with the commissioner on or before the effective date of the transfer or may use existing policy forms with the appropriate endorsements as allowed by the commissioner. A transferring insurer shall notify the commissioner of the proposed transfer and shall promptly file any resulting amendments to corporate documents required to be filed with the commissioner.
§ 33-2-127, MCA