Wages, Salaries, and Tips
Wages are generally subject to tax withholding by the employer. Upon being hired, an employee files Form W-4 to advise the employer of the employee's status for withholding. A nonresident student should check the "Single" box on Form W-4, even if married, due to the restrictions on deductions that can be claimed by nonresidents.
The withholding calculator on www.irs.gov does not calculate for Non-Resident Alien at this time.