Deductions & credits

I ran into a similar issue.  When asked if I received the 3rd stimulus (which I didn't) I chose NO and then all of a sudden I went for owing 200 some dollars I had a refund of over 3000.  I reviewed my taxes over and filed and now I got a letter from the IRS that I miscalcuated the Recovery rebate credit and now I owe again.  I am actually eligible.  I have been trying to get through to them on the phone with no avail.  I am trying to figure out if there is a miscalculation or bug in the 2021 software.

Lisa - WI