Wis. Stat. § 631.13: Incorporation by reference.

No insurance contract may contain any agreement or incorporate any provision not fully set forth in the policy or in an application or other document attached to and made a part of the policy at the time of its delivery except that:

(1) Rates. Any policy may by reference incorporate rate schedules and classifications of risks and short-rate tables filed with the commissioner; and

(2) Complex contracts. By rule or order or by approval of a form the commissioner may authorize for complex contracts incorporation by reference of provisions for administrative arrangements, premium schedules and payment procedures.