Ugh!  Ive got a client with a similar letter about that they show a balance due based on a change they say we made to 2020...we filed a 2019 amended return (paid in full) for the same thing they say 2020 was changed for, so Im guessing its a data entry snafu on IRS's end and theyve somehow attached the 2019 situation to 2020....been fighting with this for 6 months now, cant get a human on the phone and we all know how well the mail is being handled!   

Now theyve grabbed the 2021 refund and applied it to this erroneous 2020 balance due...its all such a mess!