Recieved my irs notice and they needed a form of us not married . We were never married. Just gf/bf status only. We were told that marriage joint was a good choice when filing but we realize it was not and so we decided for me to change it to head of household. I dont know what to give them as they want a documents showing the marriage was not valid, separate maintience. Or documents saying we didnt live with each other. What should i do ? Thanks in advance.