Tax residency is one of the most misunderstood concepts in international taxation. Many individuals assume that residency is based solely on immigration status or physical location, but U.S. tax residency follows a separate and highly technical set of rules.

This guide explains how U.S. tax residency works for citizens, green card holders, and foreign nationals, and why misunderstanding residency can lead to significant compliance issues.

Tax Residency vs Citizenship

U.S. citizenship and U.S. tax residency are related but distinct concepts. U.S. citizens are generally subject to U.S. taxation on worldwide income regardless of where they live, while non-citizens may become U.S. tax residents based on presence or immigration status.

Green Card Holders and Tax Residency

Green card holders are generally treated as U.S. tax residents from the date lawful permanent residence is granted. This residency typically continues until the green card is formally surrendered or revoked.

The Substantial Presence Test Explained

Foreign nationals without green cards may still become U.S. tax residents if they meet the substantial presence test. This test measures days of physical presence in the United States over a three-year period.

Resident Alien vs Nonresident Alien

Tax classification determines how income is reported and taxed. Resident aliens are taxed similarly to U.S. citizens, while nonresident aliens are taxed primarily on U.S.-source income.

Dual-Status Taxpayers

Individuals who change residency status during the year may be considered dual-status taxpayers. Dual-status filings require special reporting and often involve both resident and nonresident rules.

Tax Treaties and Residency Tie-Breaker Rules

U.S. tax treaties may override domestic residency rules in certain cases. Tie-breaker provisions help determine residency when an individual is considered a resident of two countries.

Common Residency Mistakes

Common mistakes include assuming visa status determines tax residency, failing to track days accurately, and misunderstanding treaty benefits.

When Residency Planning Matters

Proper residency planning can significantly affect tax exposure, reporting requirements, and compliance risk. Planning is especially important before moving to or from the United States.