To comply with the requirements of the Foreign Account Tax Compliance Act (FATCA), financial institutions are required to determine whether a client is considered a U.S. Person for U.S. tax purposes.
In general, a U.S. Person includes:
U.S. citizens, regardless of where they reside;
U.S. tax residents, including Green Card holders and individuals who meet the Substantial Presence Test;
Companies, partnerships and other legal entities incorporated or organised under the laws of the United States or any of its states;
Certain trusts, estates and other legal entities that are treated as U.S. Persons under U.S. tax law.
Please note that this is a general summary and is not an exhaustive definition. If you are unsure whether you qualify as a U.S. Person, you should consult a qualified tax adviser or refer to the official guidance published by the U.S. Internal Revenue Service (IRS).
Official sources:
Classification of taxpayers for U.S. tax purposes
Foreign Account Tax Compliance Act (FATCA)