someone correct me if I'm wrong, but......

I believe that additional 0.9% is withholding & your final "bill" will be based on your adjusted gross income when you file your tax return.

also, I thought I read somewhere that the company is obligated to start the additional withholding after you exceed the $200K mark - because they don't know if you'll file as an individual or jointly

so.....you may get some/all of that "Fed Addl Med" back if your AGI comes in below the limits ($250K jointly - $200K individually)

I'm sure I'm way off, but that's what I recall hearing/reading......