Tax Atlas

Am I a tax resident of the United States?

Short answer: usually yes once you cross 183 daysInternal Revenue Service (IRS)“You will be considered a United States resident for tax purposes if you meet the substantial presence test for the calendar year. To meet this test, you must be physically present in the United States (U.S.) on at least:”View source · accessed 2026-08-20 in a year. But a day count is only the headline test — a home, family, or economic ties can pull you in sooner, and staying under it does not automatically keep you out.

Verified August 20, 2026 by Henning Stanger, Authorized Accountant (Autorisert regnskapsfører) · not tax advice

The residency test in the United States

The number that decides it: 183 daysInternal Revenue Service (IRS)“You will be considered a United States resident for tax purposes if you meet the substantial presence test for the calendar year. To meet this test, you must be physically present in the United States (U.S.) on at least:”View source · accessed 2026-08-20. Cross that in a year, and the United States counts you as tax resident. This is the Substantial Presence Test (SPT), and it applies only to non-citizens (green card holders and citizens are taxed on worldwide income regardless of days present -- see citizenship-based taxation). It is not a simple single-year count like most countries on this site: a non-citizen becomes a US tax resident by being present at least 31 days in the current year AND at least 183 weighted days when adding all current-year days plus one-third of the prior year's days plus one-sixth of the days from the year before that -- so averaging around 122 days a year for three straight years alone can trigger residency.

Closer connection exception
Even a non-citizen who technically meets the Substantial Presence Test can still be treated as a non-resident alien for the year if they can show a 'tax home' in, and a closer connection to, another country -- provided they were not present in the US for 183+ days in the current year by itself. [source]Internal Revenue Service (IRS)“you can still be treated as a nonresident of the United States for U.S. tax purposes if you qualify for one of the following exceptions”View source · accessed 2026-08-20
Non resident alien taxation
Individuals who are neither citizens, green card holders, nor Substantial-Presence-Test residents are 'non-resident aliens' and are taxed only on US-source income -- the mirror image of the worldwide-income rule that applies to citizens, green card holders, and resident aliens. [source]PwC Worldwide Tax Summaries“Non-resident aliens are taxed on their US-source income and income effectively connected with a US trade or business (with certain exceptions).”View source · accessed 2026-08-20
Green card holder worldwide tax
Green card holders are taxed exactly like citizens on worldwide income, and remain resident aliens for tax purposes even after moving abroad indefinitely -- residency does not lapse just because someone leaves the country; it continues until the green card is formally given up. [source]PwC Worldwide Tax Summaries“All lawful permanent residents for immigration purposes (i.e. 'green card' holders). Resident alien status generally continues until the green card is formally relinquished.”View source · accessed 2026-08-20
Citizenship based taxation
The single most important fact distinguishing the US from virtually every other country on this site, which use physical-presence or ties-based residency tests: the US taxes its citizens (and green card holders) on worldwide income no matter where they live or how many days they spend inside the US. Day-counting rules like the Substantial Presence Test only govern whether a non-citizen becomes a US tax resident -- they are irrelevant to a citizen or green card holder, who stays fully taxable on worldwide income until they formally renounce citizenship or relinquish the green card. [source]Internal Revenue Service (IRS)“You are subject to tax on worldwide income from all sources and must report all taxable income and pay taxes according to the Internal Revenue Code.”View source · accessed 2026-08-20

If you're close to the line

A day count only helps if the count is right. Travel that crosses midnight, short trips home, and which end of a stay counts as arrival or departure all change the total — and get miscounted constantly.

The free 183 Days residency tracker logs your actual travel and checks it against the United States’s verified threshold, so you are working from a real count instead of a guess.

What residency actually changes

Once you are tax resident, the United States generally taxes your worldwide income, topping out at 37%PwC Worldwide Tax Summaries“For individuals, the top federal income tax rate for 2025 is 37%, except for long-term capital gains and qualified dividends”View source · accessed 2026-08-20. Federal top marginal rate on ordinary income for 2025, made permanent (along with the rest of the TCJA bracket structure) by the One Big Beautiful Bill Act (OBBBA). This is a progressive, multi-bracket system -- the 37% rate applies only to income above roughly USD 626,350 for single filers, with lower brackets applying below that. Most US states add their own income tax on top of the federal rate, so effective top marginal rates vary significantly by state (see state_income_tax_addon). Stay a non-resident, and the United States typically taxes only income sourced there.

Full picture: the United States tax guide.

Frequently asked questions

How many days can I spend in the United States before becoming a tax resident?

183 days. This is the Substantial Presence Test (SPT), and it applies only to non-citizens (green card holders and citizens are taxed on worldwide income regardless of days present -- see citizenship-based taxation). It is not a simple single-year count like most countries on this site: a non-citizen becomes a US tax resident by being present at least 31 days in the current year AND at least 183 weighted days when adding all current-year days plus one-third of the prior year's days plus one-sixth of the days from the year before that -- so averaging around 122 days a year for three straight years alone can trigger residency. Arrival and departure days are counted according to the United States's own rule, not a universal convention — check the source below for the exact method.

Can I become a tax resident of the United States even under the day count?

Yes, in some cases. the United States also has rules beyond the simple day count — see the detail below. A permanent home, family, or economic ties can trigger residency independent of days spent.

What does tax residency in the United States actually cost me?

the United States's income tax tops out at 37%. Federal top marginal rate on ordinary income for 2025, made permanent (along with the rest of the TCJA bracket structure) by the One Big Beautiful Bill Act (OBBBA). This is a progressive, multi-bracket system -- the 37% rate applies only to income above roughly USD 626,350 for single filers, with lower brackets applying below that. Most US states add their own income tax on top of the federal rate, so effective top marginal rates vary significantly by state (see state_income_tax_addon). Residency is what makes you liable for it in the first place — non-residents are typically taxed only on the United States-source income, not worldwide income.

Sources

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When to talk to an advisor

This page maps the United States’s general residency test. It cannot weigh your treaty position, your specific ties, or the timing of a move. If meaningful money depends on the answer, have a qualified advisor in the United States (and in your home country) review your situation before you act.