Wis. Stat. § 102.22

(1) If the employer or his or her insurer inexcusably delays in making the first payment that is due an injured employee for more than 30 days after the date on which the employee leaves work as a result of an injury and if the amount due is $500 or more, the payments as to which the delay is found shall be increased by 10 percent. If the employer or his or her insurer inexcusably delays in making the first payment that is due an injured employee for more than 14 days after the date on which the employee leaves work as a result of an injury, the payments as to which the delay is found may be increased by 10 percent. If the employer or his or her insurer inexcusably delays for any length of time in making any other payment that is due an injured employee, the payments as to which the delay is found may be increased by 10 percent. If the delay is chargeable to the employer and not to the insurer, s. 102.62 applies and the relative liability of the parties shall be fixed and discharged as provided in that section. The department or the division may also order the employer or insurance carrier to reimburse the employee for any finance charges, collection charges, or interest that the employee paid as a result of the inexcusable delay by the employer or insurance carrier.

(2) If any sum that the department or the division orders to be paid is not paid when due, that sum shall bear interest at the rate of 10 percent per year. The state is liable for interest on awards issued against it under this chapter. The department or the division has jurisdiction to issue an award for payment of interest under this subsection at any time within one year after the date of its order or, if the order is appealed, within one year after final court determination. Interest awarded under this subsection becomes due from the date the examiner's order becomes final or from the date of a decision by the commission, whichever is later.

(3) If upon petition for review the commission affirms an examiner's order, interest at the rate of 7 percent per year on the amount ordered by the examiner shall be due for the period beginning on the 21st day after the date of the examiner's order and ending on the date paid under the commission's decision. If upon petition for judicial review under s. 102.23 the court affirms the commission's decision, interest at the rate of 7 percent per year on the amount ordered by the examiner shall be due up to the date of the commission's decision, and thereafter interest shall be computed under sub. (2) .