Unless you are a permanent resident (green card holder) you must use W-8BEN. The regulation under which the financial institutions operate adheres to a more strict definition of U.S. resident than the IRS rules for filing tax returns. In other words, being a U.S. resident for income tax purposes does not make you a "permanent resident" for purposes of the banking regulation.
If you are a green card holder, use the Form W-9.
See this IRS link form more information on form W-8BEN.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"