2025年9月11日 How to Determine U.S. Tax Residency: Master Worldwide Taxation Rules in 3 Minutes
Are You a U.S. Tax Resident？
Clarify your tax status quickly to avoid unexpected worldwide taxation.
For those who have just obtained a U.S. visa, are planning to immigrate, or have started working in the United States, the first question you must answer is：
Am I considered a U.S. tax resident？
Don’t assume that only Green Card holders are tax residents. Even short-term visitors, dependents, or those on family visits may unintentionally become U.S. tax residents if their stay in the U.S. is long enough—triggering an obligation to report and pay taxes on worldwide income.
This guide explains in just three minutes how to determine your U.S. tax residency using the Substantial Presence Test (SPT) and the Green Card Test, so you can prepare for U.S. tax compliance.
U.S. Tax Residency Categories
Tax Resident vs. Nonresident Alien
| Tax Status | Definition & Requirements |
|---|---|
| Tax Resident | Must report worldwide income, including U.S. and foreign earnings. Subject to the full U.S. tax system and reporting obligations. |
| Nonresident Alien | Only required to report U.S.-sourced income (e.g., wages, rental income, interest). |
How to Determine U.S. Tax Residency？
Three main tests apply：
1. Green Card Test
If you hold a Green Card (Permanent Resident Card)
at any point during the year, you are considered a U.S. tax resident for that entire year
, regardless of actual time spent in the U.S.
Green Card = worldwide income reporting obligation.
2. Substantial Presence Test, SPT
Even without a Green Card, you may qualify as a tax resident if you spend too many days in the U.S.
SPT Formula：
(Current year days in the U.S.)
+ (1/3 of prior year’s days)
+ (1/6 of days two years prior)
≥ 183 days
Requirement：You must also have at least 31 days in the U.S. during the current year.
Example Calculation：
2025: 130 days
2024: 120 days × 1/3 = 40
2023: 120 days × 1/6 = 20
Total = 130 + 40 + 20 = 190 days (≥183 ➜ Tax Resident)
3. Election to Be Treated as a Tax Resident
Even if you do not meet the Green Card Test or SPT, you may elect to be treated as a U.S. tax resident under certain conditions：
Filing jointly with a U.S. citizen or Green Card holder spouse (Married Filing Jointly)
Choosing First-Year Choice as a new immigrant for favorable tax treatment
Who Is Exempt from Being Treated as a U.S. Tax Resident？
Three common categories of exemptions：
| Exempt Category | Explanation |
|---|---|
| F-1 / J-1 Students or Scholars | First 5 years are excluded from SPT, generally considered nonresidents |
| Diplomats, Religious Workers | Certain exemptions apply |
| Medical Exceptions | Days of presence due to medical conditions may be excluded |
Why Does Tax Residency Status Matter？
Tax residency directly determines your obligations under worldwide taxation and foreign asset reporting.
Once classified as a U.S. tax resident, you must：
Report worldwide income (Global Income)
Disclose foreign accounts and assets (FBAR / FATCA)
Failure to comply may lead to heavy penalties or even account freezes.
Common Q&A
U.S. Tax Residency Clarified
01．I’m not a U.S. citizen and don’t have a Green Card. I’m not a tax resident, right？
Wrong.
If you meet the SPT requirements, you are still considered a tax resident.
02．I’m a dependent or on a student visa. Do I still need to file taxes？
Partially true.
F-1 / J-1 visa holders are exempt from SPT for the first 5 years, so they are usually nonresidents.
However, if you have U.S.-sourced income, you still need to file taxes and submit Form 8843 to claim the exemption.
03．I just entered the U.S. this year. I won’t be taxed on worldwide income, right？
It depends.
New immigrants entering in the second half of the year may elect First-Year Choice, reporting only post-arrival income.
But if you file jointly with your spouse, you may be treated as a full-year tax resident.
04．I live and work in Taiwan. Do I still need to file U.S. taxes？
Yes.
If you are a U.S. tax resident (e.g., Green Card holder), you must report worldwide income—even if earned entirely outside the U.S.
05．If I don’t transfer my foreign income into the U.S., do I still need to report it？
Absolutely.
Under worldwide taxation, remittance to the U.S. is irrelevant. All income must be reported.
06．My spouse and I have different tax residency statuses. Can we file separately？ Which is better？
Yes, you may choose：
Married Filing Separately (nonresident spouse not subject to worldwide taxation)
Married Filing Jointly (nonresident spouse elects to be treated as a tax resident and reports worldwide income)