What is the US substantial presence test?

The IRS counts all days in the current year, one third of the days in the first preceding year and one sixth of the days in the second preceding year. Both the current-year minimum and weighted three-year total must be considered. A tracker that looks only at a flat yearly total cannot answer that test by itself.

The rule is often described as 31 current-year days and 183 weighted days across the three-year period. Those figures are part of the IRS test, not a substitute for reading the conditions and exclusions that apply to your own presence in the United States.

The rule has exceptions

The IRS guidance covers exclusions and exceptions, including situations involving exempt individuals and closer connections. A treaty can also be relevant. This is why a flat 183-day counter cannot decide a US tax position by itself.

Whether a day is counted can be as important as the final arithmetic. Check the current IRS guidance before filing or changing plans, and take qualified US tax advice when the result has consequences. Do not infer a residence result from one number in an app or online calculator.

Keep the record before you need it

Maintain a complete day record across multiple years, including documents that explain unusual days or exceptions. Record arrival and departure dates promptly, correct a missing journey while it is still fresh, and retain the source records an adviser may need to understand an unusual period.

The tax-residency tracker overview explains the early-warning use case. For the product boundary, read limits and scope. Use the IRS guidance and qualified US tax advice for a final position.

How Flags helps

Flags: Tax Residency can help you retain a private travel-day record and flag the United States for review. It does not calculate the full weighted test, exceptions or treaty position; treat it as an early warning, not an SPT calculator. Review the underlying stays first, then confirm the applicable rule outside the app.

Flags is an early-warning tool, not tax advice; confirm with a qualified adviser.