Once you have received a W-8BEN, you can return the completed form by mail, or by fax to:

U.S. Bank 
Tax Reporting Operations
SL-MO-T6CD
PO Box 524
St. Louis, MO 63166-0524

Fax: (314) 418-3530

Your form will be processed by the Tax Reporting Operations teams. If you are due a refund, a credit will be given the account it was accessed on.

To learn more about the W-8BEN, you can visit About Form W-8 BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting (Individuals) | Internal Revenue Service (irs.gov).