Key definitions important to the U.S. tax process for foreign nationals:
Non-resident Alien:If you are an alien (not a U.S. citizen), you are considered a nonresident alien unless you meet one of two tests. You are a resident alien of the United States for tax purposes if you meet either the green card test or the substantial presence test for the calendar year (January 1-December 31).
Non-resident Alien for Tax purposes:An alien is any individual who is not a U.S. citizen or U.S. national. A nonresident alien is an alien who has not passed the green card test or the substantial presence test .
Resident Alien for Tax purposes:A Resident alien for tax purposes is an international person who has been physically present in the United States for the amount of time required to meet the substantial presence test for their particular visa type. The status is determined based on the substantial presence test and the visa type of the individual. Resident Aliens for tax purposes are taxed in the same manner as a U.S. citizen.
U.S. Resident:Any person who is a U.S. citizen, U.S. national, Asylee, Refugee or Permanent Resident.