Checked against IRS sources on July 4, 2026.
For the federal Substantial Presence Test, the IRS definition of "United States" is narrower than many travelers expect in some places, and broader in others.
IRS sources say the term includes all 50 states, the District of Columbia, US territorial waters, and certain adjacent seabed and subsoil areas. The IRS also says the term does not include US territories or US airspace for SPT.
Short answer: US territory days and US airspace are excluded from the IRS SPT definition of "United States." Do not turn that into a broader claim about every tax, immigration, or territory-residence rule.
Jetseen helps you track days - always consult a qualified tax professional for advice specific to your situation.
What is the Substantial Presence Test?
The IRS says the Substantial Presence Test has two parts.
You need at least 31 days of physical presence in the United States during the current year. You also need 183 weighted days across the current year and the two prior years.
The weighted formula counts:
| Year | Days counted |
|---|---|
| Current year | All US days |
| Prior year | One-third of US days |
| Second prior year | One-sixth of US days |
This guide is not a full SPT explainer. It answers one narrow question: what counts as "United States" for the SPT definition.
What does the IRS include?
For SPT, IRS sources say "United States" includes:
- all 50 states
- the District of Columbia
- US territorial waters
- certain adjacent seabed and subsoil areas over which the United States has exclusive rights under international law to explore and exploit natural resources
That territorial-water detail is easy to miss. A record that only says "not on land" may not be enough for advisor review.
What does the IRS exclude?
IRS sources say the term "United States" does not include US territories or US airspace for purposes of SPT.
That means the federal SPT definition is not the same as casual language about "US places."
Examples to record separately:
- Puerto Rico
- US Virgin Islands
- Guam
- American Samoa
- Northern Mariana Islands
- flight time over US airspace
The IRS SPT page uses the category "US territories." This guide names common examples for clarity, but it does not give territory-specific tax-residence rules.
Does that mean territory days never matter?
No.
Do not stretch the SPT definition into a claim about every tax purpose. Territory tax residency, local filing duties, immigration status, treaty positions, and other federal rules can require separate analysis.
The narrow source-backed point is this: for the federal SPT definition of "United States," IRS sources exclude US territories and US airspace.
That is useful. It is not the whole tax answer for someone spending meaningful time in Puerto Rico, the US Virgin Islands, Guam, or another US territory.
How should you track mixed US and territory trips?
Keep the timeline granular.
Track:
- arrival and departure dates for the 50 states and DC
- US territorial-water facts if relevant
- territory arrival and departure dates
- air-transit notes
- documents that support each segment
- advisor notes on which rule you are reviewing
Do not merge "US mainland," "Puerto Rico," and "airspace" into one travel label. The IRS SPT definition treats them differently.
Where Jetseen fits
Jetseen includes US SPT as a named rule type. It also supports trip records, notes, documents, alerts, and CSV export.
A practical setup:
- track US SPT days in the US tracker
- keep territory stays as separate trip records
- add notes for airspace or transit facts
- attach travel documents where the distinction may matter
- export CSV records for accountant or advisor review
Jetseen does not determine US tax residency, decide territory tax status, apply FEIE rules, prepare Forms 8840 or 8843, apply treaties, or replace professional tax advice.
If your travel crosses the US mainland, US territories, and flight segments, Try Jetseen Free for 14 Days and keep the records separate before the weighted SPT calculation gets messy.
Jetseen helps you track days - always consult a qualified tax professional for advice specific to your situation.
Sources
Disclaimer: This article is for informational purposes only and does not constitute legal or tax advice. Tax residency rules change frequently. Consult a qualified tax professional for advice specific to your situation.