Aliens who are residents of the United States are generally subject to the same tax rules as U.S. citizens, including Self-Employment Contributions Act (SECA) tax rules. Residents of the Virgin Islands, Puerto Rico, Guam, or American Samoa are also subject to SECA tax. Self-employment activities of U.S. citizens in these regions plus the Northern Mariana Islands are subject to SECA tax.
Nonresident aliens will be subject to SECA tax on income earned in the U.S. unless they are a citizen of a country that has a social security agreement or treaty in effect with the U.S. If an agreement is in effect, the terms of the agreement will dictate the rules.
Currently there are agreements in effect with Austria, Belgium, Canada,
Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. For more
information, contact the social security agency of the relevant country, or the
U.S. Social Security Administration, Office of International Programs, P.O. Box
17741, Baltimore, MD 21235.