Wis. Stat. § 345.08: Suit to recover protested tax or fee.

No suit shall be maintained in any court to restrain or delay the collection or payment of the taxes levied or the fees imposed or enacted in chs. 341 to 349. The aggrieved taxpayer shall pay the tax or fee as and when due and, if paid under protest, may at any time within 90 days from the date of such payment sue the state in an action at law to recover the tax or fee so paid. If it is finally determined that such tax or fee or any part thereof was wrongfully collected for any reason, the secretary of administration shall pay from the transportation fund the amount of such tax or fee so adjudged to have been wrongfully collected. A separate suit need not be filed for each separate payment made by any taxpayer, but a recovery may be had in one suit for as many payments as were made within the 90-day period preceding the commencement of the action. Such suits shall be commenced as provided in s. 775.01.