香港人唔使畀股息稅,但要畀withholding tax
https://www.investopedia.com/ask/answers/06/nonusresidenttax.asp
Nonresident Alien
If you fall under the nonresident alien category and the only business you have in the U.S. is investments–such as stocks, mutual funds, and commodities–held with a U.S. dollar–denominated brokerage firm or other agent, you are subject to the following tax guidelines.
Capital Gains
Nonresident aliens are subject to no U.S. capital gains tax, and no money will be withheld by the brokerage firm.2 However, this does not mean that you can trade tax-free. You will likely need to pay capital gains tax in your country of origin.
Dividend
Nonresident aliens are subject to a dividend tax rate of 30% on dividends paid out by U.S. companies. However, they are excluded from this tax if the dividends are paid by foreign companies or are interest-related dividends or short-term capital gain dividends.3 The 30% tax rate can also be lower depending on the treaty between your home country and the U.S. As a result, it's important that you contact your brokerage firm to verify the rate.5
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