Any mutual under ch. 611 or 612 and any service corporation under ch. 613 may issue policies to any public or private corporation, board or association or to any unit of government, in any place in this state or elsewhere where it is authorized to do an insurance business. Any public or private corporation, board or association or unit of government in this state that is authorized to acquire insurance may make applications, enter into agreements for and hold policies in any mutual insurer or service corporation authorized under ch. 611, 612, 613 or 618.
Wis. Stat. § 631.03