IRS Form W-8BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting (Individuals) - https://www.irs.gov/forms-pubs/about-form-w-8-ben
You must give Form W-8BEN to the withholding agent or payer if you are a nonresident alien who is the beneficial owner of an amount subject to withholding, or if you are an account holder of an FFI documenting yourself as a nonresident alien.