The latest deficit number is a staggering $11.5 billion. That's fueled by a tanking economy but also by Illinois' long history of failing to pay its Medicaid bills and its massive, growing pension debt.

Simply put, Illinois does not have enough revenue to pay its bills -- and it can't be all chalked up to reckless spending. That remains a major issue, and we'll detail what needs to change below. But Illinois will never cut its way to solvency, as the chart below indicates.

The graphic, compliments of the Center for Tax and Budget Accountability in Chicago, lays out the long-term reality in Illinois. It projects Illinois spending and revenues going forward, accounting only for inflation and population growth. It assumes no growth in programs.

The bottom line: It shows an ever-widening gap between what the state will spend and its tax revenue.

Other, compelling reasons also bolster the case for an income tax increase in Illinois, from the current 3 percent to at least 4 percent:

• • Illinois' total state and local tax and fee burden as a percentage of personal income is among the lowest of all states, according to 2006 data collected by the Federation of Tax Administrators and distributed by CTBA.

• • Illinois has not raised its income tax rate in 20 years. At the same time, the state's tax base has been hurt as high-paying manufacturing jobs have been replaced by lower-paying service jobs.

• • The state's unfunded pension liability, likely the highest in the nation, is now more than $73 billion.

• • The alternative to a tax increase is devastating budget cuts, which will inevitably lead to job losses, potentially prolonging the recession.

But an income tax increase alone isn't enough. Illinois now has one of the country's more regressive tax systems. It's time to shift the burden to those who can pay more. Quinn looks headed in that direction, saying Friday his plan includes a tax cut for lower income workers.

The tax increase -- which should go to pay for current expenses, not new ones -- must be coupled with major budget cuts and real reforms, several of which were outlined by the Civic Federation, another reputable Chicago research group.

The state must bring down costs for its overly generous pension system, starting with more modest benefits for new workers and potentially requiring current employees to contribute more. It must also consider scaling back free health care for retirees and improve management of the Medicaid program.

The challenges are enormous, but not insurmountable. Kudos to Gov. Quinn for taking the first step.