I know all of the interest reported as federal tax free is taxable in WI. Since I have muni bonds issued by multiple states, I entered multiple states in lieu of listing each state. I learned from another response to a similar question that I needed to go into the actual 1099 form and change the MX to XX. That forced all of the tax exempt interest amount to go to line 2 on the Wisconsin Form 1 from line 2a on the 1040SR. Now I'm confident that it is being reported correctly.
