Nonresident alien: the key tax facts
Nonresident alien is a tax status, not an immigration one, and the two do not always agree. It matters because it decides the most basic question on the return: whether the United States taxes your worldwide income, or only the part of it that is US-sourced.
How the status is determined
You are a resident alien for tax purposes if you meet either the green-card test or the substantial presence test. Fail both, and you are a nonresident alien. There is no third option, and no election to simply pick the one you prefer.
The green-card test is the simple one: lawful permanent resident status at any point in the year makes you a resident for that year. The substantial presence test counts days, and it is where most of the argument happens.
What changes on the return
The scope of income. A resident alien reports worldwide income, exactly as a citizen does. A nonresident alien reports US-source income only.
The form. Nonresident aliens file Form 1040-NR rather than Form 1040.
The reporting obligations. FBAR and FATCA reporting attach to US persons. A nonresident alien is generally outside both — which is precisely why the status question has to be settled before anyone starts listing accounts.
The deductions available. Most nonresident aliens cannot claim the standard deduction, and filing jointly is not ordinarily available.
When two countries both claim you
It is entirely possible to be a tax resident of the United States and of your host country under each country's own rules. Where a treaty exists, it supplies a tie-breaker: a sequence of tests running through permanent home, centre of vital interests, habitual abode and finally citizenship.
Relying on a treaty position is a disclosure, not a private decision — it goes on Form 8833 with the return. If you are weighing one, that is a conversation to have before the return is prepared rather than after.
The case that catches people
A nonresident alien spouse is the common one. Electing to treat that spouse as a US resident can produce a better joint result, but the election brings their worldwide income into the US return and carries their foreign accounts with it. It is worth modelling both ways before choosing.
IRC §7701(b), §871 and §6013(g); IRS Publication 519; Form 1040-NR and Form 8833 instructions. Treaty outcomes depend on the specific treaty in force. Checked 13 September 2026.
Unsure which side of the line you fall on?
The status question is worth settling before the return is prepared, not after.