Arrive partway through a year and you usually fail the day-count test for that year, which makes you a non-resident for the whole of it. There is an election in the statute that can change the answer, and the arithmetic gating it is exact: a run of at least thirty-one consecutive days, and seventy-five percent presence from that run’s first day to the end of the year. This works the gate. It does not tell you whether to walk through it.
An individual is treated as a resident for a calendar year IF AND ONLY IF they meet one of three tests: lawful permanent residence, the substantial presence test, or this first-year election. Somebody who arrives in, say, September usually meets neither of the first two for that year. The election is the third door, and it exists precisely for the year of arrival.
The first arithmetic condition is presence in the United States for a period of AT LEAST 31 CONSECUTIVE DAYS in the election year. Consecutive is the operative word: thirty-one days scattered across the autumn does not satisfy it, and the run chosen becomes the anchor for the second condition. Where several qualifying runs exist, which one is chosen changes the second test's answer.
The second condition is presence, during the period beginning with the FIRST DAY OF THAT 31-DAY RUN and ending with the LAST DAY OF THE ELECTION YEAR, for a number of days equal to or exceeding SEVENTY-FIVE PERCENT of the days in that testing period. The statute allows the individual to be treated as present for up to five days of absence in aggregate within the testing period. Both numbers matter and the second one is the tolerance that saves ordinary lives — a short trip inside the testing window need not break it.
The election is available only to somebody who was NOT a resident under the permanent-residence or substantial-presence tests in the calendar year IMMEDIATELY PRECEDING the election year, and who is not already a resident under those tests for the election year itself. It is a first-year provision in the literal sense — it does not help somebody who was resident last year, and it is not a switch that can be flipped in any year the arithmetic happens to suit.
This page deliberately does not tell you whether to make the election, and that omission is the important one. Whether it helps depends on your income, on a spouse’s position, on foreign tax credits and on treaty positions — it is genuinely a preparer’s judgement, and a calculator that worked out eligibility and then implied “so do it” would be doing the harm this surface exists to prevent. It also says nothing about the separate elections that let a non-resident spouse be treated as a resident: they interact with this one, and none was read from a primary source here. Whether you are already resident without any election is a different question, at Am I a US Tax Resident?
We already computed the public version — it is complete and stays free. Keep your arrival and travel dates in one place and the Square has them at filing time: Join DesiSquare and the Square remembers your dates, re-runs this when the rules change, and puts a credentialed human one message away.