Hong Kong does have much lower taxes, however, the united states is one of the few nations that actually taxes its citizens. So even if you don't live or work in the US, if you are a US citizen, then you pay US taxes. You can deduct your Hong Kong taxes from this, so it's not like you are paying double, but you don't just pay US taxes. However, there is something you can set up, I'm not too familiar with, but you can avoid paying US income tax as long as you don't even step foot inb the US for at least two years, but then after that if you come back, even for a day, you have to start paying taxes again.