Presence in the United States
For purposes of this subsection—
(A) In general Except as provided in subparagraph (B), (C), or (D), an individual shall be treated as present in the United States on any day if such individual is physically present in the United States at any time during such day.
(B) Commuters from Canada or Mexico If an individual regularly commutes to employment (or self-employment) in the United States from a place of residence in Canada or Mexico, such individual shall not be treated as present in the United States on any day during which he so commutes.
(C) Transit between 2 foreign points If an individual, who is in transit between 2 points outside the United States, is physically present in the United States for less than 24 hours, such individual shall not be treated as present in the United States on any day during such transit.
(D) Crew members temporarily present An individual who is temporarily present in the United States on any day as a regular member of the crew of a foreign vessel engaged in transportation between the United States and a foreign country or a possession of the United States shall not be treated as present in the United States on such day unless such individual otherwise engages in any trade or business in the United States on such day.