Thanks for the quick response. Line 32 is blank on my return, so there are no adjustments to the total tax on line 24.
Working backwards on the TT forms, the wrong number is on the Est Tax Options worksheet as 100% of my 2020 taxes. Following the data source for that, it takes me to "Carryover Worksheet Line 6 (2nd col)". The data source for that is "Form 2210 Line 4" where it is listed as my current year tax. That number comes from lines 1 & 2 on that form. Line 1 is my correct tax after credits. Line 2 is only part of my self-employment tax. The data source for line 2 is Sch SE-T line 12 which lists my full self-employment tax.
So I have no idea where the incorrect number came from.
I've used the correct number from 1040 line 24 (minus 0 line 32 credits) as my 100% of 2020 number to calculate my estimated tax payments, so I don't need this fixed for me personally. But TT could be leading others astray so they are underpaying their estimated taxes. I nearly underpaid mine by $8000 based on what TT shows as my 100% option.
