If you are a nonresident alien admitted to the United States as a student, you generally are not permitted to work for a wage or salary or to engage in business while you are in the United States. In some cases, a student admitted to the United States in “F–1,” “M–1,” or “J–1” status is granted permission to work, and it is so noted on the student's copy of Immigration Form I–94, Arrival-Departure Record. Social security and Medicare taxes are not withheld from pay for the work unless the student is considered a resident alien.

Any student who is enrolled and regularly attending classes at a school may be exempt from social security and Medicare taxes on pay for services performed for that school.

The U.S. Citizenship and Immigration Services (USCIS) permits on-campus work for students in “F–1” status if it does not displace a U.S. resident. On-campus work means work performed on the school's premises. On-campus work includes work performed at an off-campus location that is educationally affiliated with the school. On-campus work under the terms of a scholarship, fellowship, or assistantship is considered part of the academic program of a student taking a full course of study and is permitted by the USCIS. In this case, the educational institution endorses the Form I–20. Social security and Medicare taxes (FICA) are not withheld from pay for this work unless the student is considered a resident alien.

Students in “F–1” status may be permitted to participate in a curricular practical training program that is an integral part of an established curriculum. Curricular practical training includes work/study programs, internships, and cooperative education programs. In this case, the educational institution endorses the Form I-20. Social security and Medicare taxes are not withheld from pay for this work unless the student is considered a resident alien.

Employment due to severe economic necessity and for optional practical training is sometimes permitted for students in “F–1” status. Students granted permission to work due to severe economic necessity or for optional practical training will be issued Form I–688B or Form I–766 by the USCIS. Social security and Medicare taxes are not withheld from pay for this work unless the student is considered a resident alien.

Students in “M–1” status who have completed a course of study can accept employment for practical training for up to six months and must have a Form I–688B or Form I–766 issued by the USCIS. Social security and Medicare taxes are not withheld from “M–1” students' pay for these services unless the student is considered a resident alien.

In all other cases, any services performed by a nonresident alien student are not considered as performed to carry out the purpose for which the student was admitted to the United States. Social security and Medicare taxes (FICA) will be withheld from pay for the services unless the pay is exempt under the Internal Revenue Code.

Nonresident aliens are admitted to the United States as nonimmigrant exchange visitors under section 101(a)(15)(J) of the Immigration and Nationality Act through the sponsorship of approved organizations and institutions that are responsible for establishing a program for the exchange visitor and for any later modification of that program. Generally, an exchange visitor who has the permission of the sponsor can work for the same reasons as the students discussed above. In these cases, permission is granted by a letter from the exchange visitor's sponsor or by endorsement from the program sponsor on Form IAP–66, Certificate of Eligibility or Form DS–2019.

Social security and Medicare taxes (FICA) are not withheld on pay for services of an exchange visitor who has been given permission to work and who possesses or obtains a letter of authorization from the sponsor unless the exchange visitor is considered a resident alien.

In all other cases, services performed by an exchange visitor are not considered as performed to carry out the purpose for which the visitor was admitted to the United States. Social security and Medicare taxes are withheld from pay for the services unless the pay is exempt under the Internal Revenue Code.

If you are a “J–1” visa holder, your spouse or child may be permitted to work in the United States with the prior approval of the USCIS and issuance of Form I–688B or Form I–766.

Nonresident aliens admitted to the United States as participants in cultural exchange programs under section 101(a)(15)(Q) of the Immigration and Nationality Act may be exempt from Social security and Medicare taxes - FICA. Aliens with “Q” visas are aliens whose employment or training affords the opportunity for culture-sharing with the American public. They are allowed to work in the United States for a specific employer in an approved cultural exchange program. The employer must be the petitioner through whom the alien obtained the “Q” visa. Social security and Medicare taxes are not withheld from pay for this work unless the alien is considered a resident alien. Aliens with “Q” visas are not permitted to engage in employment outside the exchange program activities.

If you work as an employee in the United States, in most cases you must pay Social security and Medicare taxes also known as FICA . Your payments of these taxes contribute to your coverage under the U.S. social security system. Social security coverage provides retirement benefits and medical insurance (Medicare) benefits to individuals who meet certain eligibility requirements.

In most cases, the first $87,000 of taxable wages received in 2007 for services performed in the United States is subject to social security tax. All taxable wages are subject to Medicare tax. Your employer deducts these taxes from each wage payment. Your employer must deduct these taxes even if you do not expect to qualify for social security or Medicare benefits. You can claim a credit for excess social security tax on your income tax return if you have more than one employer and the amount deducted from your combined wages for 2007 is more than $5,394. Use the worksheet in chapter 3 of Publication 505, Tax Withholding and Estimated Tax, to figure your credit.

If any one employer deducted more than $5,394, you cannot claim a credit for that amount. Ask your employer to refund the excess.

In general, U.S. social security and Medicare taxes apply to payments of wages for services performed as an employee in the United States, regardless of the citizenship or residence of either the employee or the employer. In limited situations, these taxes apply to wages for services performed outside the United States. Your employer should be able to tell you if Social security and Medicare taxes apply to your wages. You cannot make voluntary payments if no taxes are due.

For more information, please read IRS Publication 519.