Substantial presence test 2026: US income tax rates and the 31 and 183-day count

The United States decides your tax status for each calendar year, and it starts from status and arithmetic, not from where your life is centred. A citizen is outside this test altogether: the IRS's Publication 519 covers aliens, meaning anyone who is not a US citizen. An alien is a resident for tax purposes if they hold a green card at any time in the year, or if they meet the substantial presence test. Otherwise they are a nonresident alien. The difference is large. Resident aliens are generally taxed like citizens on their worldwide income, at graduated rates that for 2026 go from 10% to 37%. Nonresident aliens are taxed only on US-source income and on income connected with a US trade or business. Income from a US trade or business is taxed at those same graduated rates, and most other US-source income at a flat 30% or a lower treaty rate. That is why a few extra days can change what you report, from a part of your income to all of it.

Federal tax in 2026: the seven brackets

Federal tax, single filer, on taxable income. States levy their own taxes.

Those are the IRS's figures for a single filer, published with Revenue Procedure 2025-32, for returns filed in 2027. Married couples filing jointly have their own thresholds: 12% over US$24,800, 22% over US$100,800, 24% over US$211,400, 32% over US$403,550, 35% over US$512,450 and 37% over US$768,700. The brackets apply to taxable income, after the standard deduction of US$16,100 for single filers and married people filing separately, US$32,200 for joint returns and US$24,150 for heads of household. Personal exemptions stay at zero. These are federal figures only. States have their own taxes, which this page does not cover.

How your status changes the bill, according to Publication 519:

The two ways to become a US tax resident

Green card test

You are a resident if you are a lawful permanent resident at any time during the calendar year, which you generally are if USCIS issued you a Permanent Resident Card. No days are needed. The status continues until you voluntarily renounce it in writing to USCIS, or until it is administratively or judicially terminated. Publication 519 is firm on this: until you have proof the letter was received, you remain a resident alien for tax purposes, even with a card over 10 years old or after a long absence. A treaty tiebreaker can make a green card holder a nonresident for figuring tax, but the same publication warns this can trigger the expatriation tax in some cases. A long-term resident who ends that status should read that part first.

Substantial presence test

You need at least 31 days of physical presence in the current year, and at least 183 days over 3 years counted as all days this year, 1/3 of last year's and 1/6 of the year before. The IRS's own example is 120 days in each of 3 years: 120, plus 40, plus 20, is 180, so the test is not met. It is closer than it looks. The same engine that runs the calculator gives these results:

The fourth line is the 31-day floor at work: with 30 days this year you do not meet the test, whatever came before. The last line shows the one-year route. Steady visits are the trap: at 122 days a year, the test gives 183 weighted days, so it is met in the third year without ever coming near 183 days in one year. At 121 days a year, it is not.

Days that do not count, and how to keep them out

Any part of a day counts as a day of presence. That covers arrival and departure days, with the exceptions the IRS lists: commuting regularly from Canada or Mexico, being in the US for less than 24 hours in transit between two foreign places, being a crew member of a foreign vessel, being unable to leave because of a medical condition that arose in the US, and days as an exempt individual. "United States" means the 50 states and the District of Columbia and their territorial waters, but not US territories or airspace.

Each exception has a catch. Transit does not cover a business meeting, even one held at the airport. A regular commuter must commute on more than 75% of workdays. The medical exception does not apply to a condition you already knew about when you arrived, or if you stay beyond a reasonable time after you could leave. Excluded days as an exempt individual or for a medical condition also need Form 8843, so the exclusion comes with paperwork.

Meeting the test is not always the end. With fewer than 183 days this year, a foreign tax home and a closer connection to a foreign country, you can remain a nonresident through the closer connection exception and Form 8840, unless you have taken steps towards a green card. A treaty tiebreaker can also make you a nonresident for tax purposes. That takes Form 1040-NR with Form 8833.

The first and last year, and leaving

You can be both a nonresident and a resident in the same year, typically when you arrive or leave. Under the substantial presence test your residency starting date is generally the first day you are present that year, though up to 10 days can be ignored with a signed statement if you can show a closer connection and a foreign tax home for those days. A newcomer who does not pass either test this year but will pass next year can sometimes choose to be treated as a resident from a date this year, if they spend at least 31 days in a row in the US and at least 75% of the days from then until the end of the year. That is the first-year choice, and it has its own statement.

Before leaving the US, an alien generally must obtain a certificate of compliance, the so-called sailing permit, by filing Form 1040-C or Form 2063 with an IRS office at least 2 weeks before departure, unless they are in one of the listed categories. It does not replace the annual return. Publication 519 in its 2025 edition sets the 1040-NR deadline at April 15, 2026 for people with wages subject to withholding and June 15, 2026 for those without. We quote the edition we read, so check the 2026 dates when it appears.

Why this calculator wants three years of days

A single total cannot answer this test. The law weights each year differently, and the fractions leave remainders: 100 days last year is 33 and a third. The IRS example divides evenly, so it does not show how a remainder is treated; our engine keeps exact sixths without rounding, and shows how many days you have left this year. Excluded days go in the advanced section. The IRS page behind each rule is in the sources at the end of this page. It stops at the point where facts take over: it does not decide on your green card, your closer connection or a treaty. Those depend on documents and on the IRS's assessment. The IRS also provides interactive tools for international taxpayers, which you can check against this count.

A day counter for the whole year, with arrivals and departures logged as you travel, is what the Taxlag app is for. To compare with other countries, see tax residency by country. A second country can claim you too: France, the United Kingdom and the UAE each apply their own test, and the dual residency guide explains how a treaty separates them.