A more thorough explanation:

Definition: A United States person is someone who is a resident or national of the United States, with the exception of someone who lives outside the United States and works for a non-U.S. person. It also includes any American business or organization, as well as any foreign subsidiary or affiliate of an American business that is controlled by the American business.

Examples:

• A U.S. citizen who lives in California
• An American company that sells products in Europe
• A foreign subsidiary of a U.S. company that is controlled by the U.S. company

These examples illustrate that a United States person can be an individual or a business, and that it includes both domestic and foreign entities that are controlled by American businesses.