> You're probably instead thinking of income tax, which the US does levy worldwide contrary to virtually every other nation on Earth and is, I can tell you from personal experience, not fun.

That's certainly what I was thinking of, given I have a few US friends here in the UK. Isn't the way to stop that to simply give up dual citizenship?

From one perspective, yes, you can get around this by simply giving up dual citizenship.

From the perspective of one's whole life, once that US citizenship is gone, it's gone. You can't reinstate it like you can with many other nations. And losing first-class access to the world's greatest economy is a very heavy price to pay. It only makes sense if you are absolutely sure you, and by extension your children and their grandchildren and their grandgrandchildren (because they only get US citizenship at birth if you yourself are a US citizen at their birth), will never want to have anything to do with the US again.

Ultimately I decided against it. The idea that I have a country I can always move to and conservatively 3-5x my take home pay compared to even one of the best paying countries in Europe is one hell of a liberating feeling. Don't discount that kind of optionality lightly.

You won't be double taxed, the US taxes the difference between your local income tax rate and the US federal tax rate. So if you live in London you're not paying any US tax because the UK income tax rate is higher. It helps stop rich people from "totally live in <tax haven>". If only we had that for companies..

I think where people get confused is that it's implemented as a tax credit which is equal to the income tax you pay locally.

On top of that the first $130k earned is also exempt, so it only applies to high earners as well