The W-8 BEN form is used to declare to the U.S. government that you are not a U.S. person, and therefore, you are not subject to certain U.S. taxes (such as capital gains tax).
As long as you are not a U.S. citizen, green card holder, or a legal U.S. resident, it is mandatory to submit the W-8 BEN form when opening an account.
During the process of opening a GUGU account, the system will automatically generate and submit the W-8 BEN form on your behalf.
Updated