What if I make a mistake when I am using TeleFile?
If you realize the mistake before you have received the confirmation number, hang up, redial, and begin again. If you already received the confirmation number, you must file a paper return (Form ST-12) to amend your TeleFile return. Check the box on the top of page 1 to indicate the return is amended. Follow the instructions on page 6 of Form S-114, “Instructions for Wisconsin Sales and Use Tax Return,…”.