What is a resident alien for tax purposes? A resident alien for tax purposes is a non-U.S. citizen who meets either the lawful permanent residence (“Green Card”) test or the Substantial Presence Test. Related articles: What is the Green Card Test?What is the Substantial Presence Test?What is a nonresident alien for tax purposes? Updated on September 30, 2021 Tagged: resident alientax Was this article helpful? Yes No Need Support?Can't find the answer you're looking for?Contact Support