How it works
It applies to non-US citizens without a green card, like a European couple on a long US road trip. US citizens aren't affected by this test at all.
Any part of a day counts as a full day. Cross the border at 11 pm and that day counts.
Some days don't count
Under 24 hours in the US while in transit between two foreign places, days you regularly commute in from Canada or Mexico, days as crew on a foreign ship, days you can't leave because of a medical condition that started while you were in the US, and days as an exempt individual (certain student, teacher and diplomat visas). Tourists on ESTA or a B visa are not exempt.
The count works by calendar year and starts fresh each January 1, but last year's and the year before's days keep feeding in at 1/3 and 1/6.
If you pass, you can still be treated as a nonresident under the closer connection exception: you were in the US fewer than 183 days this year, kept your tax home in one foreign country all year, had closer ties there than to the US, and haven't applied for a green card. You claim it by filing Form 8840 on time.
An example
Anna from Germany spends 150 days in the US in 2024 and 120 days in 2025. In 2026 she drives the US from April 1 to August 8, which is 130 days. Her 2026 count is 130 + 40 (1/3 of 120) + 25 (1/6 of 150) = 195, so she meets the test for 2026. Because her 2026 days alone are under 183 and her home and life are in Germany, she can look at the closer connection exception and Form 8840.
Mistakes people make
- Only counting this year. Two long trips in a row can push you over 183 even if no single year looks big.
- Thinking arrival and departure days don't count. Any part of a day in the US is a day.
- Mixing up the visa clock and the tax clock. Staying legal on your visa or ESTA says nothing about whether you've become a tax resident.
- Assuming a tourist visa makes you exempt. The exempt categories are specific student, teacher and diplomat visas, not tourist status.
- Missing Form 8840. It's due when a Form 1040-NR would be: April 15 if you had US wages with tax withheld, otherwise June 15. File it late and you generally can't claim the closer connection exception.
Quick answers
Does the Substantial Presence Test apply to US citizens?
No. It only applies to people who aren't US citizens or green card holders.
How does the IRS count my days?
Every day this year, plus a third of last year's days, plus a sixth of the days from the year before. You also need at least 31 days this year.
I'm on ESTA or a tourist visa. Do my days count?
Yes. Tourists aren't exempt, and any part of a day in the US counts as a full day.
Can I pass the test and still be treated as a nonresident?
Possibly, through the closer connection exception. You need fewer than 183 days this year, a tax home and closer ties in one foreign country, and Form 8840 filed on time.
Where this comes from
Government sources only. Read the rule yourself.
What changed
3 Oct 2026. Checked against the IRS. No change.
A plain-language summary of the official rules. It isn't legal advice. If your situation is unusual, confirm with the relevant authority or a qualified adviser.
