We are in the same situation. My fiancée and I co-signed on the house together, but since we are not married, we file separately. Both of our returns are being rejected because of this.
We have a friend who completes our taxes and sends us the files and paperwork. Every year, I buy the software just to e-file, but I should have just mailed them in after she sent us the paperwork and saved myself the cost of the software this year.
