The residency start date: the most important date in your move
Every pre immigration decision is measured against one date. Get it wrong by a few weeks and planning that looked complete becomes planning that arrived late.
The green card test
Residency begins on the first day of physical presence in the US as a lawful permanent resident. If the status is granted while you are already in the country, it begins on the day of approval.
The substantial presence test
You meet the test if you are present at least 31 days in the current year and 183 days on the weighted count: all days this year, one third of last year's days, one sixth of the year before. Meeting the test makes you resident for the whole year from your first day of presence, subject to a limited exception for a small number of days.
183
Business trips in the two years before a move count. People planning a January arrival regularly discover they were already resident from a March scouting trip the previous year.
Dual status years and the first year choice
In the year you arrive, you are typically nonresident for part of it and resident for the rest. A dual status return taxes only US source income before the start date and worldwide income after it, and comes with restrictions: no standard deduction, no joint filing in the ordinary course.
Electing to be treated as resident for the full year, or making the first year choice to start residency earlier, can be better where a spouse has little income or where deductions are significant. It is arithmetic, and it should be run both ways.
Can the start date be moved?
Sometimes, by managing days of presence, by the closer connection exception, or by a treaty tiebreaker. All of them have to be arranged before the days are spent.
Reviewed by an IRS Enrolled Agent
Last reviewed January 2026
This article is general information, not tax or legal advice. Thresholds, rates, and procedures change, and whether any of it applies depends on your specific facts.