4.3.1 (a) Residence of IndividualsUnder U.S domestic tax law, all individuals are subject to U.S tax, unless specifically exempted.U.S citizens are subject to U.S. tax on a worldwide...
4.5.2 [a] New Tie-Breaker RuleIf a particular company is a resident of both Canada and the United States, the language of new Article IV(3)[a] provides that where a company...
Ref Code Section 871 (b) and 882:
According to these code sections if a foreign person is engaged in a U.S trade or business, he is subject to U.S taxes for any income that is connected...