Occasionally, a non-US corporation’s expansion of its business into the United States has unforeseen or unintended state income tax consequences. While federal income taxation is generally a matter of primary concern when a non-US corporation starts conducting business in the United States, the conclusions reached on federal income taxation do not necessarily carry over for state income tax purposes.  For example, many companies are surprised to learn that a lack of federal income tax jurisdiction does not necessarily equate to a lack of state tax jurisdiction and that a lack of federal taxable income does not necessarily equate to a lack of state taxable income.  In this article, we discuss some of the main differences between the federal income taxation and state income taxation of non-US corporations.