I received a letter from state (WI) DOR. It is saying we owe (turbo tax predicted a refund) due to earned income credit being inaccurate. Is this our error or theirs?

If you were a full year resident, did not file MFS, and received the federal, then you qualify for the WI EIC.IT is a straightforward multiply the federal by a percentage based on the number of children. Two children is 11%. You need to contact the department in your letter. They may need proof of your children living with you, your identity, something. You will need to disagree with the letter and show that you do qualify.

Hi Amy! 
Thank you so much for your reply! We did have a new dependent added to last years return, so maybe that’s contributing. We also had to mail our taxes so maybe the EIC form somehow wasn’t included? Either way I thank you for your help and I’ll call the number in the letter tomorrow! 
Callie