Form 2210 (Underpayment of Estimated Tax by Individuals, Estates, and Trusts). I understand you generally treat tax withheld from your paycheck as having been withheld evenly throughout the year. But I also understand that you can use the actual amount held in Line 11 of Form 2210 by looking at my paystubs from 4/15/2011, 6/15/2011, 9/15/2011, and 1/15/2022 to see how much was actually withheld during each payment period.
On Form 2210 line 11 where you put the estimated tax paid and tax withheld for each quarter, do I include Additional Medicare tax withheld from my paychecks? It seems I should since 90% of current year tax liability include the Additional Medicare Tax, but the Form 2210 Instruction isn't clear on this point.
