Estimate a tax refund or amount owed in Illinois from income and taxes already withheld.
Estimates a tax outcome in Illinois: federal bracket tax plus an estimated state component, minus credits, compared with what you already had withheld.
Outcome
Refund = withheld − total tax (negative means owed)
Estimate only — not a tax filing.
A big refund means you overpaid all year — many people prefer a smaller refund and larger paychecks.
Rates are approximate reference values. Local rates, exemptions and rules can differ, so treat the output as a planning figure only.