Wis. Stat. § 71.362: Situs of income.

(1) All tax-option items of nonresident individuals, nonresident estates and nonresident trusts derived from a tax-option corporation not requiring apportionment under sub. (2) shall follow the situs of the business of the corporation from which they are derived, except that all income that is realized from the sale of or purchase and subsequent sale or redemption of lottery prizes if the winning tickets were originally bought in this state shall be allocated to this state.

(2) Nonresident individuals, nonresident estates and nonresident trusts deriving income from a tax-option corporation which is engaged in business within and without this state shall be taxed only on the income of the corporation derived from business transacted and property located in this state and losses and other items of the corporation deductible by such shareholders shall be limited to their proportionate share of the Wisconsin loss or other item, except that all income that is realized from the sale of or purchase and subsequent sale or redemption of lottery prizes if the winning tickets were originally bought in this state shall be allocated to this state. For purposes of this subsection, all intangible income of tax-option corporations passed through to shareholders is business income that follows the situs of the business, except that all income that is realized from the sale of or purchase and subsequent sale or redemption of lottery prizes if the winning tickets were originally bought in this state shall be allocated to this state.