If you are a non-US resident, and you are the ‘beneficial owner’ of funds that would be subject to US tax withholding, then it will be necessary to complete form W-8BEN. Form W-8BEN is automatically created when you complete your profile information. Part I of the form is completed with your general profile information (name, address, etc), and Part II of the form is completed using these four fields in the profile information workflow:
These fields refer to International Tax Treaties between the US and various countries, if they exist. If you are unsure if you should complete these fields in the workflow, feel free to refer to the IRS instructions for completing form W-8BEN. The section pertaining to Part II of the form (specifically, lines 9 and 10) will have more context as to what these fields refer to.
Additionally, this page has official IRS documents pertaining to international tax treaties. Those documents will contain information that will be useful to completing this section of the form, if you choose to do so.
If you have additional questions about the form, the best course of action would be to contact your stock plan administrator, or to consult with a trusted tax advisor.
***all screenshots in this article reference data from a demo site; none of the information displayed relates to any real-world companies, people, or holdings.