Does the additional revenue that comes from a tax increase get cancelled out, in whole or in part, because taxpayers — especially high earners — leave or change their residence? Astonishingly, nobody in Illinois government has attempted to answer these questions and the state has no data, no study, no clue. I’ve asked several legislators from both parties and searched myself, but nothing is there. The anecdotal evidence says the problem is severe. Examples are reported publicly fairly often. Tax planners say changes of claimed residency are now shooting up. A partner at a major Chicago law