Thanks. The bottom line is that Turbo Tax is saying I owe the entire "additional Medicare tax" of 0.9% on filing, even though we withheld all of that (at least on a single filer basis for both me and my spouse) during the year. In actuality I believe we should only owe an additional $1,350 of additional Medicare tax (I ran different numbers and that seems to always be the answer regardless of income from going to single to joint; basically that is just (200 + 200 - 250) *0.9%). Again, my pay stub has a breakout that explicitly says "Medicare surtax", and I can replicate the calcs as 0.9% over 200k. So it seems like TT is not giving us credit for that in its calculations.
