Illinois has a 3% state income tax. That's the lowest rate of any of the 41 states that levy an income tax. This is the main reason why the state budget is perpetually in the red and why we are a low tax state.
This simple concept is christened "the big lie" by the Illinois Policy Institute. In this policy brief, Policy Director Mike Van Winkle argues that even though it is true that taxes levied by the State of Illinois are below the national average (see this chart from the Tax Foundation to compare all 50 states, and this fact sheet on Illinois), we should consider Illinois a higher-tax state because of federal taxes paid.
In other words, even though Illinois taxes are lower than most states, we should consider Illinois a 'high tax' state because the federal government's relatively high income tax hits Illinois residents. And we have more wealthy residents, proportionately, than most other states. Therefore, the State of Illinois ought not raise taxes to fund investments in our economy like public schools or health care.
It's important to call this out now, because we are under-investing in Illinois due to our low tax status. Too many Illinois children never develop their full potential because they don't have good teachers. Too many Illinois residents never get back to work when the get sick because they don't have good doctors and nurses and hospitals to take care of them early. Too many hours are spent stuck in traffic because we don't invest in our transportation infrastructure.
The State of Illinois is the organization that can boost our economy with these investments, and the way those investments are financed is through general taxes.
Illinois *is* a low-tax state, no matter what the Illinois Policy Institute would have you believe.