Almost everyone who earns income in the United States is required to file a federal tax return.
Resident Alien vs. Nonresident Alien
- Resident alien β green card holder or meets the substantial presence test (183+ days). Files the same as a citizen β Form 1040.
- Non-resident alien β fewer than 183 days. Files Form 1040-NR. Only income from U.S. sources is taxed.
Substantial Presence Test
Calculated using the following formula: all days in the current year + 1/3 of days in the prior year + 1/6 of days in the year before that. If the total is 183 or more, you are a tax resident.