People moving to the US often assume income tax is a problem only for green card holders or people with a steady job. Not quite: for the IRS, the question is whether you are a resident or a nonresident for tax purposes, and the answer defines what you must report. It does not depend only on your visa.
How the IRS decides
For the IRS, anyone who is not a US citizen is treated as a nonresident unless they pass one of two tests in the calendar year (January 1 to December 31):
- Green card test: you were a lawful permanent resident (you had a green card) at any time during the year.
- Substantial presence test: you were in the US at least 31 days in the year and at least 183 days over a three-year period, counting all days in the current year, plus 1/3 of the days in the previous year, plus 1/6 of the days in the year before that.
The IRS's own example: someone who spent 120 days in the US in each of 2023, 2024 and 2025 counts, for 2025, 120 + 40 + 20 = 180 days. That is below 183, so they are not a resident under this test.
What changes between resident and nonresident
- Resident: taxed on worldwide income, like a US citizen.
- Nonresident: taxed on income from US sources, and on income connected with a US trade or business.
In the year you arrive in or leave the country, you can be both, and you must file a dual-status return.
Which return to file
Residents use Form 1040, and nonresidents use Form 1040-NR. In general, a nonresident must file if they had US business activity or US income that was not fully taxed at the source. The deadline is generally April 15 for people who receive wages subject to withholding or have a US business office, and June 15 in other cases, for calendar-year filers. Even someone not required to file may need to do so to claim a refund of overwithheld tax.
Students and visitors
Days of some groups do not count toward the substantial presence test, the so-called exempt individuals. This applies, for example, to students on F, J, M or Q visas who comply with the visa's requirements. Anyone using this exemption must file Form 8843 on time, or they lose the right to exclude those days.
When you need an ITIN
The ITIN is a nine-digit number, starting with 9, issued by the IRS to people who cannot get an SSN but need a number to file taxes. It can also be requested for spouses and dependents in certain cases. Remember what it does not do: the ITIN is for federal tax purposes only, does not authorize work, does not change immigration status, does not replace an SSN and does not qualify the holder for all tax credits. You apply with Form W-7, with documents proving identity and foreign status (a valid passport can generally stand alone) and, generally, with the tax return attached. If you are eligible for an SSN, you should get the SSN, not an ITIN. See the article on how to get an SSN.
What to do now
Count your days in the US year by year, keep records of entries and exits, and check your situation on the IRS website. Brazil has its own rules for people who move and for people with income there, and that goes beyond what the IRS sources explain. For your case, look for an accountant with experience with immigrants.