While it's still complicated, many countries use the notion of "tax resident", usually defined as "somebody who spend more than 180 days / year physically at ou

While it's still complicated, many countries use the notion of "tax resident", usually defined as "somebody who spend more than 180 days / year physically at our territory". While it doesn't help US residents, as they have to pay Uncle Sam wherever they live, many non-US people are using this loophole to avoid being taxed anywhere. Just find 3 countries with residence-based taxation, avoid staying more than 180 days in a year in any of them moving back and forth, and boom! Zero taxes. (YMMV, IANAL)