After you file

Then that is even more of a reason to contact the IRS and speak with an agent to find out what they would need from you to refute this claim of income.  You are essentially disagreeing with the the CP2000 notice.  See this IRS website for a CP2000 - <a rel="nofollow" target="_blank" href="https://www.irs.gov/individuals/understanding-your-cp2000-notice">https://www.irs.gov/individuals/un...>