Backers of the plan argue most Illinoisans would get a tax cut.
Senator Don Harmon, a Democrat from Oak Park, says this provides the state a new choice, instead of extending the 2011 income tax hike or making deep cuts to services.
"We can continue an unfair, regressive tax at 5 percent, or we can cut government services, the services upon which folks rely ... by 20 percent across-the-board.
Under the plan, it's estimated the state would take in $23 million less than this year's revenue, something advocate Emily Miller says isn't necessarily a bad thing. Miller is with Voices for Illinois Children, which is among the groups pushing for a progressive tax.
"These are not good times. Families need tax cuts and government needs to be able to operate efficiently."
Implementing a progressive tax would require amending the Illinois Constitution. If approved by the House and Senate, voters would have the final say in November.