We had this problem too (2023 taxes). Here's how I unraveled the discrepancy - Click over to Forms, and on Form 2210, look at Part I, Line 6. That's the total federal withholding number they are using (which didn't match my 4 quarterly totals). Double click that number and a worksheet will pop up showing how they calculated your Federal Withholding. In our case, we discovered it was including Additional Medicare Tax that we paid as part of the total federal withholding.
