We will take care of W-2 filing. You must handle the filing of Form WT-7, the Annual Reconciliation of Wisconsin Income Tax Withheld, with the state of Wisconsin. Transmit forms electronically if you're submitting 10 or more wage statements. Otherwise, you can mail the form to Wisconsin's Department of Revenue. The due date to file Form WT-7 is February 01, @taxyear+1.