Resident alien

Your status is decided one calendar year at a time. The green card test makes you a resident alien if you are a lawful permanent resident at any time that year. The substantial presence test does so if you spend enough days in the US. Some new arrivals who pass neither test can elect resident status through the first-year choice. Every other non-citizen is a nonresident alien, generally taxed only on US-source income and income tied to a US business.

As a resident alien, you file Form 1040 and report income from every country, as a citizen does. In the year you arrive, you usually become a resident alien on your first day here. Before that day you count as a nonresident alien, which makes the year dual-status. In later years, you are a resident alien from January 1, as long as you were a resident at some point the year before.

Resident alien is a tax status, separate from your immigration status. An H-1B worker in the US all year is usually a resident alien, though the visa itself is temporary. The two tests do not apply to estate and gift tax, which look to your domicile instead.