Wis. Stat. § 40.40: State-federal agreement.

The secretary may, upon receipt of a certified copy of a resolution adopted by the governing body of any employer in accordance with s. 40.41 execute on behalf of the state a modification of the state-federal agreement with the secretary of the federal department of health and human services for the inclusion of a coverage group of the employees of the employer under the OASDHI system in conformity with federal regulations. The state and each employer included under the agreement or modification of the agreement shall thereafter be bound by federal regulations.