Yes, TurboTax will automatically correct the excess Medicare withholding on your tax return. It will include Form 8959 in your tax return to calculate the correct amount of Additional Medicare Tax that you have to pay, and include that in your total tax. The full amount of Additional Medicare Tax that was withheld from your pay will be added to your federal income tax withheld. The result is that you will pay only the correct amount, and the excess $450 that was withheld will be credited towards your income tax. This is how the IRS requires it to be handled.
