Illinois Income Tax Calculator 2025. The illinois tax calculator is for the 2025 tax year which means you can use it for estimating your 2026 tax return in illinois, the calculator allows you to calculate income tax and payroll taxes and deductions in illinois. The illinois tax estimator will let you calculate your state taxes for the tax year.

Although illinois has a flat income. Calculated using the illinois state tax tables and allowances for 2025 by selecting your filing status and entering your income for 2025 for a.