IRS Form 1120F:
Foreign corporation files this form to report their income, gains, losses, deductions, credits, and to figure their U.S. income tax liability.
 
 
 a foreign corporation must file Form 1120-F if, during the tax year, the corporation:
Was engaged in a trade or business in the United States, whether or not it had U.S. source income from that trade or business, and whether or not income from such trade or business is exempt from U.S. tax under a tax treaty (see also Protective Return Filers , later);
Had income, gains, or losses treated as if they were effectively connected with the conduct of a U.S. trade or business (see Section II , later); or
Was not engaged in a trade or business in the United States, but had income from any U.S. source, if its tax liability has not been fully satisfied by the withholding of tax at source under Chapter 3 of the Code.
Was, or had a branch that was, a qualified derivatives dealer (QDD).
 
This form is also required to be filed by:
A foreign corporation making a claim for the refund of an overpayment of tax for the tax year. See Simplified Procedure for Claiming a Refund of U.S. Tax Withheld at Source , later.
A foreign corporation claiming the benefit of any deductions or credits. See Other Filing Requirements , later.
A foreign corporation making a claim that an income treaty overruled or modified any provision of the Internal Revenue Code with respect to income derived by the foreign corporation at any time during the tax year, and such position is required to be disclosed on Form 8833. See the instructions for Form 8833 for who must file Form 8833, and who is exempt from filing by reason of a waiver provided under section 6114 and the regulations thereunder. If Form 8833 is required, complete item W(1) on page 2 of the form.
 
Others that must file Form 1120-F include the following.
A Mexican or Canadian branch of a U.S. mutual life insurance company. The branch must file Form 1120-F on the same basis as a foreign corporation if the U.S. company elects to exclude the branch's income and expenses from its own gross income.
A receiver, assignee, or trustee in dissolution or bankruptcy, if that person has or holds title to virtually all of a foreign corporation's property or business. Form 1120-F is due whether or not the property or business is being operated (see
Who Must Sign , later, for additional information).
An agent in the United States, if the foreign corporation has no office or place of business in the United States when the return is due.