@2020clearwater your actual tax $ is calculated based on schedules, worksheets, tax tables etc. this 'effective tax rate' is just an informational average calculated a certain way defined by TT, which confusingly may not use the exact numbers shown here depending on your 1040 - see previous posts on how it's defined, and see if your 1040 Line 22 divided by Line 11 gets you 12% result.
