Workers with wages and other employee compensation and/or net self-employment earnings that exceed $200,000 ($250,000 for married taxpayers; $125,000 if married filing separately) will be subject to the 0.9% Medicare surtax. Employers are required to withhold the tax when the employee's wage exceeds $200,000 for the year, regardless of whether the employee is subject to the tax or not. The difference between the actual tax liability and the actual tax is reconciled on your tax return.