It explains why MN doesn't show up on your WI Sch OS. Since you had 18 withheld, and a refund of 18, your MN net tax is zero, regardless of the actual income amounts. So it sounds like your Form calculated correctly. I know you've been confused, but I hope I've been able to help you understand somewhat what you're seeing.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
