Wis. Stat. § 11.1112: Corporations, cooperatives, and tribes.

No foreign or domestic corporation, no association organized under ch. 185 or 193, no labor organization, and no federally recognized American Indian Tribe may make a contribution to a committee, other than an independent expenditure committee or referendum committee, but may make a contribution to a segregated fund as provided under s. 11.1104 (6) in amounts not to exceed $12,000 in the aggregate in a calendar year.