FICA/ Social Security Tax
If you are an international student or scholar on an F-1 or J-1 visa, and if you are also a non-resident for federal income tax purposes, you are exempt from social security (FICA) taxes (including Medicare tax) on income earned in the United States.
If you are an F or J visa holder who is considered a resident alien for tax purposes, your wages are subject to social security (FICA) and unemployment (FUTA) taxes on the same terms which apply to U.S. citizens. J-2 and H visa holders, whether resident or nonresident are also subject to social security tax.
F-1 or J-1 students usually become residents for federal tax purposes after five years in the U.S.; J-1 scholars usually become residents after two years, including any prior time spent as an F-1 or J-1 visa holder.