The Green Card Test (GCT) is a criterion used by the Internal Revenue Service (IRS) in the United States to determine whether an individual qualifies as a "resident for tax purposes". The GCT asks whether, during the calendar year, an individual spent at least one day in the US as a lawful permanent resident (i.e. possessed a green card). In particular, it is not required to possess a green card when the individual files a return. The GCT is used alongside the Substantial Presence Test; specifically, an alien is considered a "resident for tax purposes" if they pass either the GCT or the Substantial Presence Test. Residency for income tax purposes is different than immigration purposes, i.e. an individual may be considered a resident for income tax purposes, but non-resident for immigration