Key Takeaways
- You are a US tax resident if you meet either the Substantial Presence Test or the Green Card Test
- If you move mid-year, you may be a dual-status alien — part-year resident, part-year non-resident
- Non-resident part is taxed only on US-source income; resident part is taxed on worldwide income
Substantial Presence Test
You meet the SPT if you are physically present in the US for at least 31 days during the current year AND 183 days over 3 years (counted as: all days this year + 1/3 of last year + 1/6 of the year before).
When Does Residency Start?
If SPT is met: residency starts on the first day of physical presence. For Green Card holders where SPT is not met: residency starts on the first day of arrival as a lawful permanent resident. Income earned before the residency start date is generally not taxed unless US-sourced.
Planning Tip
If you’re planning a move to the US, timing matters — smart planning in your first year of residency can make a significant difference in your tax obligations.