The 2017-2019 state budget (2017 Act 59) exempted machinery, tools, and patterns from the personal property tax effective January 1, 2018. The legislation also created a state aid program designed to reimburse municipalities for the lost personal property tax revenue. Personal property aid payments are made to municipalities in May of each year. The payment amount is based on the amount of property taxes levied in 2017 and collected in 2018 on the personal property exempted by 2017 Act 59 (i.e., machinery, tools, and patterns).
DOR posts estimates of personal property aid payments -- https://www.revenue.wi.gov/Pages/Report/personal-property-aid-estimates.aspx
In August 2020, DOR sent a letter to Local Government Leaders explaining that the department would make adjustments to personal property aid payments in 2021 to correct overpayments and underpayments that were made to some communities in 2019. Read the letter here.