Count your days: the Substantial Presence Test.
This year's US days, plus one-third of last year's, plus one-sixth of the year before. At 183, the IRS treats you as resident and taxes your worldwide income.
Figures on this page are stated for tax year 2025/26 UK · 2025 US. Thresholds change annually.
Run the arithmetic
Take your current-year days (31 minimum for the test to apply at all), add a third of last year's and a sixth of the prior year's. Arrival and departure days count as whole days — but a connection through JFK does not, provided you are in the US under 24 hours between two places outside it. Around 122 days a year, sustained across three years, crosses the line.
Over the line isn't the end: the closer-connection exception (Form 8840) or the treaty tie-breaker (Form 8833) can preserve non-resident treatment — but only if claimed, on time, on the right form.
- Formula: days + ⅓ prior year + ⅙ year before
- 183 total triggers residence; arrival and departure days count in full
- Exceptions exist but require forms, not just facts
Count your days, weighted across three years
A quick orientation, not advice — real positions have edges this cannot see.
Enter your current-year days to see the result.
Questions we get about this
Mostly yes - any day you are physically present in the US counts, including arrival and departure days.
The exception worth knowing is transit: under 24 hours in the US while travelling between two places outside it does not count at all. Medical and exempt-visa situations are also excluded, and the count here does not model those.
Treat it as a starting point. If it says an obligation applies, the next question is what the filing actually involves and whether earlier years are affected.
If it says nothing applies, it is worth re-running whenever your circumstances change - a move, a property, a new account.
It weights three years: all days in the current year, a third of the previous year, and a sixth of the year before that.
Meeting the threshold generally makes you a US tax resident for the year, regardless of visa status.
Yes. The closer connection exception and certain visa categories can override the count, and treaty tie-breaker rules may apply on top.
Those exceptions have to be claimed, and some require their own filing.
It covers the common cases and will tell you reliably whether the basics apply to you. It is a guide, not a filing position.
Edge cases - trusts, business ownership, unusual residence patterns - can change the answer, which is why the result flags when a position is worth checking properly.
Last reviewed · Figures stated for tax year 2025/26 UK · 2025 US. Thresholds and rates change annually — check figures against the current tax year before relying on them.
Got your answer and it looks complicated?
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