(1)    A 1st class city may adopt an ordinance, by a two-thirds majority vote of all members elect of the common council, to impose a sales and use tax under this subchapter at the rate of 2.0 percent of the sales price or purchase price. An ordinance adopted under this section shall be effective on January 1, April 1, July 1, or October 1, and the taxes shall be imposed only in their entirety as provided in this subchapter. A certified copy of the ordinance shall be delivered to the secretary of revenue at least 120 days prior to its effective date. No 1st class city may impose a tax under this section unless the city makes an election to join the Wisconsin Retirement System for all new employees, pursuant to s. 40.21 (7) (a), and the city contributes the amount calculated under s. 62.625 to its retirement system’s unfunded actuarial accrued liability in 2025 and in each year thereafter until the first year in which the retirement system is determined by the retirement system’s actuary to be fully funded. In addition, if the 1st class city has enacted an ordinance regarding the city’s retirement system that requires an actuary to periodically reset the actuarial contribution rate, the 1st class city may not impose a tax under this section unless the city repeals the ordinance and subsequently follows standard actuarial practices to determine contribution rates. After the retirement system is first fully funded, or until 30 years have elapsed since the effective date of the tax, whichever is earlier, the actuary shall determine all future required contributions from the city on the basis of standard actuarial practices, and the city shall repeal the ordinance imposing the tax. A certified copy of that ordinance shall be delivered to the secretary of revenue at least 120 days prior to its effective date. The repeal of any such ordinance shall be effective on December 31. A certified copy of a repeal ordinance shall be delivered to the secretary of revenue at least 120 days before the effective date of the repeal. Except as provided under s. 77.60 (9), the department of revenue may not issue any assessment or act on any claim for a refund or any claim for an adjustment under s. 77.585 after the end of the calendar year that is 4 years after the year in which the city has enacted a repeal ordinance under this section.

   (2)   

      (a)    Annually, the city shall use no more than 90 percent of the amount of revenue generated under this section in the first full calendar year in which the tax is imposed to offset the actual costs of the required payment under sub. (1) and to offset the increase in participating city agency employer contribution costs from 2022 to the current year for the retirement system established under chapter 396, laws of 1937. For purposes of this paragraph, “city agency” means any board, commission, division, department, office, or agency of the city government, including its sewerage district created under s. 200.23, school board, auditorium board, fire and police departments, annuity and pension board, board of vocational and adult education, Wisconsin Center District, housing authority, Veolia Milwaukee with respect to employees who are participants in the retirement system of Milwaukee on June 22, 2023, and public school teachers’ annuity and retirement fund, by which an employee of the city or city agency is paid.

      (b)    The city shall use an amount equal to the revenue derived from 10 percent of the amount of revenue generated under this section in the first full calendar year in which the tax is imposed to maintain a level of law enforcement and fire protective and emergency medical service that is equivalent to that provided in the 1st class city on April 1, 2023.

      (c)    In any year in which the amount of the taxes collected under this section exceeds the amount of the taxes collected in the first full calendar year and the amounts necessary to make the payments under pars. (a) and (b), the city shall use the excess revenue to implement the requirements under s. 62.90 (5) (b) and the ongoing costs of the increased number of law enforcement officers and daily staffing level of the members of the paid fire department.

   (3)   Annually, beginning in 2026, the city shall submit a report to the joint committee on finance, in the manner provided under s. 13.172 (2), containing detailed information on the city’s expenditures in the previous year from the revenues collected under this section, including expenditures and staffing levels related to law enforcement, fire protection, and other public safety measures.