It is done where the person has a tax residence. The USA is one of only 3 countries to tax you no matter where you live. Which is really painful for Americans

It is done where the person has a tax residence. The USA is one of only 3 countries to tax you no matter where you live. Which is really painful for Americans not living in the USA. They need to fix this... The rest of the world taxes you as part of a territorial system, ie, where you live and have tax residence.