Exact same story with me. Now they are demanding we send proof that we filed taxes from 2002 to 2006.
Hang tough and don’t let them bully you. I hired an old bookkeeper lady that is licensed to deal with the IRS and and she was tough with them. After the audit I owed over $80k where they reduce it to $69k because we went to the supervisor. With interest it went back to $79. They were able to put me on a do not collect program because I told them I couldn’t pay. Finally I was able to negotiate a settlement for $2,500 for every money I owed them including 2012. So almost $90k settled for $2,500.