I'm in the same situation. I had to resubmit my 2020 1040 back in mid-2021 because I accidentally sent an unsigned copy in April 2021. The IRS cashed my check back in April '21 but returned the unsigned 1040 to me in mid-2021. When I received that, I signed it and resubmitted via snail mail. Since they had already cashed my check, I didn't realize anything was amiss until I received a notice in December of 2021 saying that they never received my 1040. I assumed this was an error due to the backlog but again, I printed and signed a copy of my 1040 and re-submitted my return via snail mail. I have not done my 2021 taxes yet since I'm not able to verify if they ever received my previous 1040 form. I'm glad they got my payment but darn it, I would like to know if they received either or both of my document submissions. How can I verify that?
