Part X. Part X is used to provide information to a foreign

partner (or a pass-through entity partner with a foreign owner) to determine its tax liability or reporting requirements with respect to income effectively connected with a U.S. trade or business (ECI) or with respect to fixed, determinable, annual, or periodical (FDAP) income. Partners use the information to figure and report any U.S. tax liability on Form 1040-NR, U.S. Nonresident Alien Income Tax Return; Form 1120-F, U.S. Income Tax Return of a Foreign Corporation; or other applicable forms.