Agreement on spending and revenue does not guarantee a deal because both sides continue to negotiate non-budget issues demanded by Republican Gov. Bruce Rauner.
The governor has not been directly participating in these negotiations, though Republicans say they are working with him.
"Scott Harry, the ... governor's budget director, said without a [budget implementation bill] and also the Democrats' tax increase, we are not able to come to any conclusion, nor will we be able to come to a conclusion whether or not this is a balanced budget", Durkin said.
Governor Rauner plans to keep lawmakers in session until they agree on a budget.
Democrats and Republicans are continuing to negotiate in Springfield as IL is approaching two years without a budget.
Republicans reacted warily because Democrats have yet to submit legislation on an income-tax increase.
Senate President John Cullerton, D-Chicago, said Tuesday after a meeting between Democratic and Republican leaders that the House Democrats' plan is similar to what the Senate passed in May.
The state has been without a budget since 2015.
Republican leaders did not immediately respond to a request for comment.
Legislators have just three more days of a special session to pass a budget for entering a third consecutive fiscal year without a complete spending plan.
Durkin said his members want to tie the longevity of any tax hike to the duration of a local property tax freeze.
The Revenue and Finance Committee approved the measure 7-1 Tuesday.
Democrats say they've met Republicans more than halfway by proposing a four-year property tax freeze, when they'd originally backed one that would last half that time.
Democrats say their plan wouldn't create any new programs. The state has had no annual spending plan for two years and another fiscal year begins Saturday. The impasse between the Democratic-controlled legislature and the Republican governor has paralyzed the state so severely that Gov. Rauner even compared IL to a "banana republic" earlier this month because it can not manage its finances.
But Republicans are upset that Senate Bill 484 has exemptions for financially struggling schools including Chicago Public Schools and for municipal pensions, and that it does not include provisions that would more easily allow for voter referenda to raise or lower property taxes at the end of the freeze.