A certain number of countres lower their Income Tax to attract foreign nationals who are not happy with their countries high rates. However if nations are to compete in applying the lowest rates possible there must be a limit under which that strategy would be a loss rather than a gain.
Monaco and some other countries charge zero income taxes. So zero seems to work. It helps if you don’t have an army or try to provide free services to everyone.
You decide the free services first and then set taxes to cover that.