The taxpayer migration continues from the Land of Ever Higher Taxes.

Illinois Gov. Bruce Rauner speaks during a news conference at the state Capitol, July 26.
Illinois Gov. Bruce Rauner speaks during a news conference at the state Capitol, July 26. Photo: Justin Fowler/Associated Press

If Republicans succeed in limiting the state-and-local tax deduction, one hope is that this could finally inspire a come-to-Jesus moment in prodigal high-tax states. Democrats in Illinois ought to be especially chastened by new IRS data showing an acceleration of out-migration.

The Prairie State lost a record $4.75 billion in adjusted gross income to other states in the 2015 tax year, according to recently IRS data released. That’s up from $3.4 billion in the prior year. Many of the migrants were retirees who often flock to balmier climes. But millennials accounted for more than a third of the net outflow in tax returns.

While Florida with zero income tax was the top destination for Illinois expatriates, the Illinois Policy Institute notes that Illinois lost income and people on net to all of its neighbors—Wisconsin (6,000 people based on claimed exemptions), Indiana (8,200), Iowa (1,900), Missouri (2,000) and Kentucky (1,100). What’s the matter with Illinois?

Too much for us to distill in one editorial, but suffice to say that exorbitant property and business taxes have retarded economic growth. Illinois’s corporate tax rate is 9.5%, and pass-through business owners pay 6.45%. Though Illinois’s flat 4.95% income tax rate is relatively low compared to its neighbors, Democrats have found other ways to clobber their citizens.

Property taxes in Cook County and Chicago’s “collar” counties are the highest in the country outside of California and the Northeast. The average homeowner who moves from Lake County, Illinois, across the border to Kenosha County, Wisconsin would receive an annual $3,200 annual property tax cut. Taxes may increase as Democrats scrounge for cash to pay for pensions. Fitch Ratings reported this week that Illinois’s unfunded pension liabilities equaled 22.8% of residents’ personal income last year, compared to a median of 3.1% across all states and 1% in Florida.

This helps explain why Illinois’s economy has been stagnant, growing a meager 0.9% on an inflation-adjusted annual basis since 2012—the slowest in the Great Lakes and half as fast as the U.S. overall. This year nearly 100,000 individuals have left the Illinois labor force. The University of Illinois Flash Economic Index, which measures corporate earnings and investment as well as personal income, hit a five-year low in October. (See nearby for the recent labor force trend in Illinois and Wisconsin.)

Illinois taxpayers have seen the warnings on the wall, which became even more stark after the Democratic legislature this summer overrode GOP Gov. Bruce Rauner’s tax hike veto. Democrats in Springfield and Chicago think they can defeat Mr. Rauner next year and raise taxes again, but they may succeed mainly in driving more people out of state.

Appeared in the December 13, 2017, print edition.