SPRINGFIELD -- Rob't Green sees two things on the horizon: higher taxes in Illinois and a new home for himself in Tennessee.

"There is a $40 billion pension debt coming our way and nobody is talking about it. But one thing is for sure, taxes are going to go up in Illinois and I'm leaving," the Moline resident said.

Mr. Green, who earns about $120,000 per year, said he plans to retire from the employment recruiting firm he owns in about 2½ years.

"Right now I pay $3,500 in income tax to the state of Illinois and $9,000 in property taxes," Mr. Green said.

Tennessee has no income tax, and Mr. Green contends he only will be paying $1,000 in property taxes on a house of greater value than his current Illinois residence.

"Do people migrate to other states because of taxes? You bet. Most of the people in the Tennessee development where I may move are Midwesterners who have moved there for warmer weather and lower taxes," Mr. Green said.

The U.S. Census Bureau projects that between 1995 and 2025 Illinois will lose 1.7 million people because they will have moved to other states. During the same period the state is expected to gain 1 million people through international immigration.

This spells trouble for the state's economic future.

"We are losing high-income people to places like Scottsdale, Ariz., and gaining low-income people who will work in our service industry," said Northwestern University public policy Professor Don Haider.

"It takes five people making $20,000 moving into the state to equal the economic impact of that one person making $100,000 who moved out," said Jon Bakija, an associate professor of economics at Williams College in Massachusetts. Mr. Bakija has studied taxpayer migration between states.

Regardless of whether folks are leaving Illinois because of the taxes, the weather or some other reason, these migration trends spell trouble for the state's financial outlook.

Illinois will be less able to pay off much of the debt lawmakers have pushed into the future because so many taxpayers are leaving the state and the state's income-tax base is diminishing, Mr. Haider said.

Just why people are leaving Illinois is a bit of an open question. Like many northern states, it is losing people to the warmer weather and more robust economies in Sunbelt states. But what role tax policy plays is less clear.

But taxation experts say it plays a role with three groups: wealthy individuals, retirees and those living near state boundaries.

For example, it is not uncommon for well-heeled folks in the Iowa Quad-Cites to move just across Mississippi River to Illinois because the state has a 3 percent flat tax rate and Iowa's top bracket is 8.98 percent, said Iowa state Rep. Jamie VanFossen, R-Davenport.

University of New Hampshire economics professor Karen Conway is researching the relationship between income taxes and people moving between states.

"The influence taxes have on where most people choose to live is quite small," she said. "If you are talking about older people, they are choosing to move someplace warmer or get closer to their kids or grandkids. Those are much more important factors on what than what the tax rates are. And for most ordinary people it is not a significant factor. But I will concede for some very, very wealthy people that taxes do influence where they choose to live."

Mr. Bakija contends that inheritance taxes as well as income taxes are significant impact on why wealthy Illinoisans flee the state.

But Ms. Conway suspects that wealthy people aren't actually choosing to physically move because of taxes, but are simply establishing second homes in states with a more favorable tax climate and establishing legal residency in those places.