U.S. Green Card Test

You are a resident for tax purposes if you were a lawful permanent resident

(immigrant) of the United States at any time during the year. In most cases, you are a lawful permanent resident if the USCIS (or its predecessor organization, INS) has issued you an alien registration card, also known as a green card. You continue to have resident status under this test unless the status is taken away from you or is administratively or judicially determined to have been abandoned.