joint account和POA 不一样啊。

既然你做POA，你的名字为什么要上银行账户？本来是那个人的钱，你作为POA仅仅是可以去管理，你的名字不应该上账户。

撇开POA不说，就说两个人开共同账户，ＩＲＳ如此说　

Joint accounts.

 If two or more persons hold property (such as a savings account, bond, or stock) as joint tenants, tenants by the entirety, or tenants in common, each person's share of any interest or dividends from the property is determined by local law.

https://www.irs.gov/publications/p550#en_US_2023_publink10009846?

TIN for joint account.

 Generally, if the funds in a joint account belong to one person, list that person's name first on the account and give that person's TIN to the payer. (For information on who owns the funds in a joint account, see Joint accounts, later.) If the joint account contains combined funds, give the TIN of the person whose name is listed first on the account. This is because only one name and TIN can be shown on Form 1099.

所以我认为只要香港人列为账户第一个名字，你可以不报利息。