CP # 23. They say I underpaid in 2017 and even though I wrote a check for close to $4,000 which I sent with a paper copy of the 1040. They claim they don't have that form!. I don't write a check to the IRS w/o filing. The e-copy didn't go through....
So, I sent it by the USPS including the check. What do I do?
