How Many Days in the U.S. Make You a Tax Resident?

How the test is structured

The substantial presence test looks at physical presence over a three-year period. It requires a minimum number of days in the current year and, separately, a weighted total across the current year and the two preceding years, in which prior-year days count for less than current-year days. Because prior years carry forward at reduced weight, someone with a consistent travel pattern can meet the test without ever spending most of a single year in the country.

The arithmetic is not the interesting part

The IRS publishes the day counts and the weighting fractions. What actually determines outcomes is which days are counted at all, and whether an exception or treaty position applies.

Days that may not count

• Days present under certain visa categories, including some students, teachers, and trainees, subject to limits on how long the exclusion lasts
• Days a person was unable to leave the United States because of a medical condition that arose while present
• Days as a regular commuter from Canada or Mexico
• Days in transit through the United States under specified conditions
• Days as a crew member of a foreign vessel in certain circumstances

Excluding days is not automatic. Several of these exceptions require a filed statement — commonly Form 8843 — and failing to file it can cost the exclusion even when the underlying facts support it.

The closer connection exception

Someone who meets the day count may still be treated as a nonresident if they were present for less than a specified number of days in the year, maintained a tax home in a foreign country, and had a closer connection to that country than to the United States. Closer connection is judged on facts: where your permanent home, family, belongings, banking, driver's license, voter registration, and business ties are. It is claimed on Form 8840 and is unavailable if you have applied for a green card.

Treaty tie-breakers

If you are a resident of both the United States and a treaty partner country under each country's domestic law, the treaty's residency article generally provides a sequence of tie-breaker rules — permanent home, center of vital interests, habitual abode, nationality — to assign residency to one country. Taking a treaty position typically requires disclosure on Form 8833 and does not eliminate all U.S. filing obligations. In particular, information reporting may continue to apply.

The year you arrive or leave

Residency does not always start on January 1. A person who becomes a resident partway through the year is often a dual-status taxpayer for that year, taxed as a nonresident for part of it and as a resident for the rest. The residency starting date depends on the facts, and it is the single most valuable date in pre-immigration planning, because actions taken before it are generally outside the U.S. worldwide income net.

What to do if you are close to the line

Keep a contemporaneous travel log with entry and exit dates rather than reconstructing it from passport stamps later. Review the projected count before the end of the year, while you can still change plans. If you expect to become a resident, review foreign investments, company interests, trusts, and appreciated assets before the starting date rather than after.

Sources and official references

• IRS — Substantial Presence Test
• IRS — About Form 8843
• IRS — About Form 8840
• IRS — Tax Treaties