Wis. Stat. § 138.041: Federal rate parity.

(1) In order to prevent discrimination against state-chartered financial institutions with respect to interest rates, state-chartered banks, credit unions and savings banks may take, receive, reserve and charge on any loan or forbearance made on or after April 6, 1980 and before November 1, 1981, and on any renewal, refinancing, extension or modification made on or after April 6, 1980 and before November 1, 1981, of any loan or forbearance, interest at a federal rate prescribed for federally chartered banks, credit unions and savings banks, respectively, notwithstanding any other statutes. The federal rate described in this section does not include any rate permitted under a federal law which refers to a rate limit established by a state law which does not apply to state-chartered banks, credit unions or savings banks.

(2) In order to prevent discrimination against state-chartered financial institutions with respect to interest rates, state-chartered banks, credit unions, savings and loan associations and savings banks may take, receive, reserve and charge on any loan or forbearance made on or after November 1, 1981 and before November 1, 1984, or after October 31, 1987, and on any renewal, refinancing, extension or modification made on or after November 1, 1981 and before November 1, 1984, or after October 31, 1987, of any loan or forbearance, interest at a federal rate prescribed for federally chartered banks, credit unions, savings and loan associations and savings banks, respectively, notwithstanding any other statutes. The federal rate described in this section does not include any rate permitted under a federal law which refers to a rate limit established by a state law which does not apply to state-chartered banks, credit unions, savings and loan associations or savings banks.