Mont. Code Ann. § 33-16-306

Upon compliance with the provisions of this chapter applicable thereto, any rating organization, advisory organization, and any group, association, or other organization of admitted insurers which engages in joint underwriting or joint reinsurance through such organization or by standing agreement among the members thereof may conduct operations in this state. As respects insurance risks or operations in this state, no insurer shall be a member or subscriber of any such organization, group, or association that has not complied with the provisions of this chapter applicable to it.