Substantial Presence Test 計算機

What the test actually requires

The Substantial Presence Test is set out in the Internal Revenue Code, and it is two conditions rather than one. Meeting only the weighted total is not enough.

You are a US tax resident under the test for a calendar year if both hold:

• 你在當年實際待在美國至少 31 天，而且
• 你的加權總數達到 183 天以上：當年 + 1/3 × 前一年 + 1/6 × 前兩年

You were present in the United States on at least 31 days during the current year, and 183 or more weighted days across three years, counting every day of the current year, a third of the days of the prior year, and a sixth of the days of the year before that.

Failing this test does not mean you are outside the US net. The green-card test runs alongside it, and holding a green card makes you a resident regardless of how few days you spend in the country.

Five travel patterns, worked

The weighting is what makes the test hard to eyeball. A pattern that feels obviously safe can clear 183, and a year spent almost entirely abroad can still count.

Each row below runs the same formula: current-year days in full, prior year divided by three, the year before divided by six.

Weighted totals are rounded to two decimals.

The fourth row is the one worth remembering. Twenty-five days in the country clears 183 weighted days comfortably, and the 31-day condition is the only thing keeping that person out of residency.

Which days count

The default is broad: any day on which you were physically present in the United States at any moment counts as a full day, including the day you arrive and the day you leave.

A short list of days is excluded outright:

• Days you regularly commute to work from a residence in Canada or Mexico.
• Days you are in the United States for less than 24 hours while in transit between two places outside it.
• Days you are in the country as a crew member of a foreign vessel.
• Days you could not leave because of a medical condition that arose while you were here.

The United States means the fifty states and the District of Columbia for this purpose. Time in the US territories is generally outside the test.

豁免個人

某些類別的人完全不計入其美國天數：外國政府相關人員（A 或 G 簽證）、持 J 或 Q 簽證的教師與受訓人員（有年限）、持 F、J、M 或 Q 簽證的學生（以 5 個曆年為限），以及少數其他情形。如果你屬於豁免個人，本計算機的輸入應只包含非豁免的天數。

Some people do not count their days at all while their exempt status lasts:

• Students on F, J, M or Q visas, generally for five calendar years.
• Teachers and trainees on J or Q visas, generally for two of the previous six years.
• Individuals connected to a foreign government on A or G visas.
• Professional athletes competing in a charitable sports event.

Exempt status is not automatic in practice. It is claimed on Form 8843, and that form is filed for the year even by people with no US income to report.

What happens if you meet it

Meeting the test makes you a US tax resident, which means worldwide income is reportable, not just the income you earned in the country. The foreign-account reporting rules follow along with it.

The first year is rarely a clean split. Residency generally starts on the first day of presence in the year you meet the test, which leaves you filing as a dual-status taxpayer for that year.

There are two ways out of the result even after the day count is met: the closer-connection exception below, and a tax treaty tie-breaker.

更緊密聯繫例外

即使你通過 SPT，只要同時符合以下條件，仍可被視為非居民：當年的美國天數少於 183 天、你在外國維持稅務居所（tax home），而且你與該國有更緊密的聯繫。請提交 Form 8840 以主張該例外。

The exception is not available to everyone who wants it. It requires fewer than 183 days in the current year, a tax home in the foreign country for the whole year, and a closer connection to that country than to the United States, and it is closed off if you have applied for a green card.

When a treaty overrides the count

If your home country has a tax treaty with the United States and both countries consider you resident, the treaty's tie-breaker decides which one wins, working through permanent home, centre of vital interests, habitual abode and then nationality. A treaty result can override the day count, but it has to be claimed rather than assumed.

Common mistakes

• Counting only the current year. The two prior years carry real weight, and they are what turns a modest travel pattern into residency.
• Treating part days as part days. A two-hour layover that clears immigration is a full day.
• Assuming a visa type exempts you forever. The student and teacher exemptions run out, and the day count starts from the moment they do.
• Forgetting Form 8843. Exempt status is claimed, not granted, and the claim is a filing.
• Relying on a treaty without filing for it. A tie-breaker position is a disclosed treaty-based return position, not a private conclusion.

Go deeper

• The Substantial Presence Test explained, with the formula in plain math
• Exempt individuals: students, teachers and the day-count exclusions
• The closer-connection exception and Form 8840
• FEIE 330-day calculator, for the other side of the same move
• Treaty tie-breaker walkthrough, when two countries both claim you