A new Additional Medicare Tax went into effect on Jan. 1, 2013.

The 0.9 percent Additional Medicare Tax applies to an individual’s wages, Railroad Retirement Tax Act compensation and self-employment income that exceeds a threshold amount based on the individual’s filing status. The threshold amounts are $250,000 for married taxpayers who file jointly, $125,000 for married taxpayers who file separately and $200,000 for all other taxpayers. An employer is responsible for withholding the Additional Medicare Tax from wages or compensation it pays to an employee in excess of $200,000 in a calendar year.

On Nov. 26, 2013, the IRS and the Department of the Treasury issued final regulations which provide guidance for employers and individuals relating to the implementation of Additional Medicare Tax, including the requirement to withhold Additional Medicare Tax on certain wages and compensation, the requirement to report Additional Medicare Tax, and the employer process for adjusting underpayments and overpayments of Additional Medicare Tax. In addition, the regulations provide guidance on the employer and individual processes for filing a claim for refund for an overpayment of Additional Medicare Tax.

When are individuals liable for Additional Medicare Tax?

An individual is liable for Additional Medicare Tax if the individual’s wages, compensation, or self-employment income (together with that of his or her spouse if filing a joint return) exceed the threshold amount for the individual’s filing status: