Alien: A term used by the Internal Revenue Service to denote an individual who is not a U.S. citizen.

Exempt Individual: A person not allowed to count days of physical presence for the Substantial Presence Test (see below), which determines whether an individual files as a resident or nonresident. Many students incorrectly construe the term to mean that they are not required to file a tax return and/or pay taxes.

Internal Revenue Service: Also known as the IRS, this is the federal agency responsible for collection of federal income taxes and enforcing tax reporting and collection laws. It is an agency of the U.S. Treasury Department.

Nonimmigrant: An individual with a permanent residence abroad and in the United States temporarily, as in the case of a foreign student.

Nonresident for Tax Purpose: An individual in the United States temporarily (usually less than six years). Although required to file an annual federal income tax return, nonresident aliens pay tax only on income from U.S. sources. Nonresidents use form 1040NR or 1040NR-EZ.

Resident for Tax Purpose: An individual who is a U.S. citizen, a U.S. permanent resident, or a nonimmigrant who has been in the United States sufficiently long to be considered a resident for tax purpose. Tax Residency is determined by the Substantial Presence Test (see below). Residents use form 1040, 1040A, or 1040EZ.

Social Security: A term used to describe an agency, a card, and two types of tax. The Social Security Administration (SSA) is an agency of the U.S. Department of Health and Human Services. The card bears a unique nine digit identification number and is issued to qualified individuals primarily to determine eligibility for social benefits earned through various forms of employment. The number on the card is also used by the IRS for data collection and record keeping. The taxes, known as FICA (Federal Insurance Contribution Act) and Medicare, are withheld by employers from workers' wages and paid to the federal government for redistribution to workers after their retirement. The FICA amount withheld from wages is 7.65 percent of total earnings up to a certain salary level. Nonresidents for tax purposes are not subject to FICA withholding. Occasionally, employers erroneously withhold this tax when students have practical training authorization, but it is possible to obtain a refund if this happens. Instructions about how to apply for this refund, and more information about this topic, can be found in the "Social Security" section in IRS Pub. 519.

Substantial Presence Test: A formula devised by the Internal Revenue Service to determine whether an alien is a resident or nonresident for tax purposes. F, J, and M students do not use the test during their first five calendar years in the United States . After that time, individuals who spend 183 days a year or more in the United States become "residents for tax purposes" for that year. The actual test can be very complicated. This general explanation may not be sufficient to meet your specific situation. For more information, refer to IRS publication 519, the US Tax guide for aliens.

Tax Treaty: An agreement between the United States and another country to determine how the country's nationals will be taxed when temporarily in the United States . A treaty can confer certain tax benefits. A note of caution, however. Tax treaties are very specific. Not all residents of a tax treaty country will qualify for tax benefits, and all treaties are slightly different. For more information, refer to IRS publication 901, US Tax Treaties.

Individual Taxpayer Identification Number (ITIN): Individuals who are not eligible for a Social Security number (routinely issued only to U.S. citizens, U.S. permanent residents, and non-immigrants authorized to work) receive from the IRS a unique nine digit number for tax purposes. This can be obtained by filing a form W-7 with the IRS.

Withholding: Deduction of a given amount of an individual's salary for purposes of meeting that individual's income tax obligation. Amounts are deducted by the employer and paid directly to the U.S. Treasury on the individual's behalf.