U.S. law treats U.S. persons and foreign persons differently for tax purposes. Therefore, it is important to be able to distinguish between these two types of taxpayers.
United States Persons

The term ''United States person'' means:

•     A citizen or resident of the United States
•     A domestic partnership
•     A domestic corporation
•     Any estate other than a foreign estate
•     Any trust if:

          o A court within the United States is able to exercise primary supervision over the administration of the trust, and
          o One or more United States persons have the authority to control all substantial decisions of the trust
    *

      Any other person that is not a foreign person.

Foreign Persons:

A foreign person includes:

    * Nonresident alien individual
    * Foreign corporation
    * Foreign partnership
    * Foreign trust
    * A foreign estate
    * Any other person that is not a U.S. person

Generally, the U.S. branch of a foreign corporation or partnership is treated as a foreign person. Refer to Internal Revenue Code section 7701(a)(31) for the definition of a foreign estate and a foreign trust..
Check-the-box Entities (See Form 8832 and Instructions)

For Federal tax purposes, certain business entities automatically are classified as corporations. Other business entities may choose how they are classified for Federal tax purposes. Except for a business entity automatically classified as a corporation, a business entity with at least two members can choose to be classified as either an association taxable as a corporation or a partnership, and a business entity with a single member can choose to be classified as either an association taxable as a corporation or disregarded as an entity separate from its owner.