Substantial Presence Test: US Tax Residency Rules

Introduction

Determining your tax residency status in the United States is a critical step in understanding your tax obligations. For non-U.S. citizens, the IRS uses the Substantial Presence Test to determine if you are considered a U.S. resident for tax purposes. If you meet the criteria of this test, you are generally treated as a U.S. resident and are subject to tax on your worldwide income, much like a U.S. citizen.

The Substantial Presence Test Calculation

To meet the Substantial Presence Test, you must be physically present in the United States on at least:

1. 31 days during the current year, and
2. 183 days during the 3-year period that includes the current year and the 2 years immediately before that.

The 183-day requirement is calculated using a weighted formula:

• All the days you were present in the current year, plus
• 1/3 of the days you were present in the first preceding year, plus
• 1/6 of the days you were present in the second preceding year.

If the weighted total is at least 183 and the current year has at least 31 countable days, you meet the SPT day-count thresholds. Exceptions and treaty provisions may affect the ultimate residency outcome. See IRC § 7701(b)(3)(A) (PDF) and Treas. Reg. § 301.7701(b)-1(c)(1) and (4) (PDF).

To select a tax year, calculate your weighted total, and see how many additional days reach the thresholds, try our free online Substantial Presence Test Calculator.

Substantial Presence Test Examples

With 120 countable days in each of three years, the total is 120 + 40 + 20 = 180. With the same prior-year counts, 122 current-year days produce 182 weighted days; 123 produce 183 and meet both thresholds.

The 31-day minimum applies separately: 30 current-year days and 365 in each prior year produce 212.5 weighted days, but do not meet both thresholds. At 31 current-year days, both thresholds are met. This is why a weighted total alone is insufficient.

Which Days Count Toward Substantial Presence?

Generally, presence during any part of a day counts as one day, including arrival and departure days. Count a calendar day only once even if you visit multiple US locations. The geographic definition includes the 50 states, the District of Columbia, and US territorial waters; it excludes US possessions and airspace. See Treas. Reg. § 301.7701(b)-1(c)(2) (PDF).

Boating, Cruises, and Territorial Waters

Being offshore does not automatically remove a day from your US count. Territorial waters and applicable day exclusions must be considered. Our guide to counting days on the water explains maritime boundaries, federal versus state treatment, and areas where interpretation remains unsettled.

Days That May Be Excluded

Specific conditions apply to each exclusion. Examples include qualifying transit of less than 24 hours between two foreign places, regular work commutes from Canada or Mexico, certain service aboard a foreign vessel, medical conditions arising in the US that prevent departure, and qualifying exempt-individual days. Do not assume a visa category or a short visit automatically qualifies. IRS Publication 519 and Form 8843 instructions discuss the conditions and documentation.

Exceptions to the Rule

Even if you meet the substantial presence test, there are important exceptions that may allow you to maintain non-resident status:

Exempt Individuals

Days spent in the U.S. by an "exempt individual" do not count toward the Substantial Presence Test. Categories of exempt individuals include:

• Qualifying foreign government-related individuals (certain A or G visas; A-3 and G-5 are excluded).
• Qualifying teachers or trainees (J or Q visas), subject to applicable time limits and status requirements.
• Qualifying students (F, J, M, or Q visas), subject to applicable time limits and status requirements.
• Professional athletes competing in charitable sports events.

The Closer Connection Exception

If you meet the Substantial Presence Test but are present in the U.S. for fewer than 183 days in the current year, you may still be treated as a non-resident alien if you can establish a "closer connection" to a foreign country. To qualify, you must:

• Maintain the required foreign tax home throughout the year (special rules can apply to a move between two foreign countries).
• Have a closer connection to that foreign country than to the United States.
• Satisfy the restrictions on steps toward lawful permanent residence and pending Green Card applications.

The Form 8840 filing requirements also apply. Filing the form alone does not establish eligibility; the underlying conditions must be satisfied.

Other Routes to Residency and Treaty Rules

The Green Card Test is a separate basis for residency. A result below the SPT thresholds does not resolve Green Card status or residency elections, including the first-year choice. Applicable treaty provisions and residency starting or ending dates can also change the analysis. Use the calculator for day-count planning and review the full circumstances with your advisor.

Burden of Proof and Record Keeping

As with many tax matters, the burden of proving your presence (or lack thereof) falls on you. Accurate record-keeping is essential. You should maintain detailed records of your travel dates, including arrival and departure days.

Use the Domicile365 App to record a detailed day-by-day log of your location. It simplifies the process of tracking your days for the Substantial Presence Test and provides the documentation you might need to support your residency status claims.

Section 877, Section 877A, and the US Exit Tax

IRC § 877 (PDF) describes the older expatriation regime. Its paragraph (h) ends its application to individuals with expatriation dates on or after June 17, 2008. The modern framework is § 877A, which incorporates certain § 877 definitions and tests.

• Who is affected: US citizens relinquishing citizenship and long-term residents ending lawful permanent resident status. Under § 877(e)(2), long-term residency generally means Green Card status in at least 8 of the preceding 15 tax years, including the expatriation year, with qualifying treaty-residence years excluded. Years based only on SPT do not satisfy that test.
• Covered-expatriate status: The tests include net worth of $2 million or more, average annual net income tax liability over the preceding five years above the applicable inflation-adjusted threshold, or failure to certify five years of federal tax compliance. Limited exceptions apply to certain dual citizens and minors, but do not remove the compliance-certification requirement.
• Potential tax: Section 877A generally treats most property of covered expatriates as sold at fair market value the day before expatriation, with an indexed gain exclusion. Deferred compensation, specified tax-deferred accounts, and nongrantor trusts have separate rules. Form 8854 reporting may be required even without an exit-tax payment.

A visitor who becomes resident solely through SPT does not trigger these expatriation rules merely by leaving. Green Card holders should review their residency history before surrendering status or claiming treaty nonresidency, which can also constitute expatriation. This day-count calculator does not perform that review.

Authority and Further Reading

Internal Revenue Code § 7701 (PDF): subsection (b)(3) sets out the Substantial Presence Test and its exceptions; (b)(7) addresses days of presence.

Treas. Reg. § 301.7701(b)-1 — Resident alien (PDF) covers the Green Card Test in paragraph (b), the SPT weights in (c)(1), physical presence and territorial waters in (c)(2), and the 31-day minimum in (c)(4).

Additional references: IRS Publication 519, Form 8840 and its instructions, and Form 8843 and its instructions. These address exclusions, closer connection, and filing requirements.

Plan and Document Your US Days

Navigating U.S. tax residency rules can be complex, but understanding the Substantial Presence Test is the first step. Whether you are counting days to avoid residency or checking if you qualify for an exception, precision is key.

The Domicile365 App is your partner in compliance, offering an easy way to log your location automatically and generate the reports you need.

Take control of your tax planning and ensure compliance by downloading the Domicile365 App today for Apple iOS or Google Android.

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