For taxes, you are either a resident alien or a nonresident alien. This is not the same as your immigration status. It decides which form you file and which income is taxed.
Resident for tax: taxed on income from everywhere in the world, like a US citizen. Files Form 1040.
Nonresident for tax: taxed mainly on US income. Files Form 1040-NR.
If you have a green card, you are a resident for tax from the day you entered as a permanent resident (the "green card test").
Everyone else: the substantial presence test
You are a resident for tax for a year if you were in the US:
At least 31 days this year, and
At least 183 days using this count: all days this year, plus one-third of the days last year, plus one-sixth of the days the year before.
Example: 120 days in each of 2024, 2025 and 2026. For 2026: 120 + 40 + 20 = 180. Less than 183, so not a resident for 2026.
Any part of a day counts as a full day.
Exempt individuals: F, J, M and Q
Some people do not count their days for a period:
Students in F, J, M or Q status: usually do not count days for 5 calendar years. Any part of a year counts as a whole year. A student arriving in August 2024 uses 2024 to 2028.
Teachers, researchers and trainees in J or Q status (not students): usually do not count days for 2 calendar years within a 6-year period.
Their spouses and children in F-2, J-2, M-2 or Q-3 status follow the same rule as the main visa holder.
After these years, the normal test applies, and many people become residents for tax.
H-1B, L-1, O-1, TN, E and H-4 holders are not exempt; they usually meet the test in their first full year.
Form 8843: everyone in F or J, even with no income
Every person who uses the exemption must file Form 8843, including spouses and children, even babies. One form per person.
Download Form 8843 from irs.gov.
Fill in Part I, and Part III (students) or Part II (teachers and trainees).
If you file Form 1040-NR, attach it.
If you do not file a return, mail it alone to the address in the form's instructions (an IRS center in Austin, Texas) by June 15. If you had US wages, file it with your return by April 15.
If you do not file it on time, you may lose the right to exclude those days.
The year you arrive or change status (for example, from F-1 to H-1B, or to a green card) may be a dual-status year: nonresident for part of the year and resident for the rest. The return is more complex:
You file a special 1040 or 1040-NR marked "Dual-Status Return".
You usually cannot take the standard deduction.
If you are married to a US citizen or resident, you may be able to choose to file jointly as residents for the whole year.
Free volunteer help (VITA) and school tax tools can help.
Thinking "I have a visa, so I am a nonresident". An H-1B worker is usually a resident for tax.
Not filing Form 8843 for a spouse or child with no income.
Counting from the visa date instead of from the calendar year.