Illinois Income Tax Rate for 2026

Examples

Illinois Income Tax Calculation Examples

The goal of these examples is to compare Single and Married Filing Jointly statuses at the same $80,000 annual income per person. The Single example uses $80,000 of household income, while the Married Filing Jointly example assumes each spouse earns $80,000, for a combined $160,000. The results match our All 50 States income tax calculator using $80,000 or $160,000 and the corresponding filing status.

To simplify the calculations, both examples assume full-year Illinois residency, W-2 wages only, no dependents, and taxpayers under age 65 who are not blind or claimed as dependents. Illinois starts with federal adjusted gross income and does not have a standard deduction. The federal standard deduction does not reduce Illinois taxable income either. These examples apply the Illinois personal exemption, with no other deductions, Illinois additions or subtractions, or tax credits. See the All 50 States calculator for a full list of assumptions and sources.

Looking at the table above, we can see that the same 4.95% tax rate applies to both Single and Married Filing Jointly statuses. The personal exemption reduces taxable income by $2,925 per person, leaving both examples with the same 4.77% effective tax rate. Before rounding, the joint tax equals the combined tax of two single filers who each earn $80,000. Filing jointly therefore produces no Illinois marriage penalty in this simplified comparison. Next, we will review the step-by-step calculations for each filing status.

Step-by-Step Example 1: Single

For a single filer with $80,000 of household income, the 2026 Illinois personal exemption is $2,925. With wages only and no other adjustments, subtracting the exemption gives the taxable income that Illinois calls net income.

• Taxable income: Subtract the personal exemption from household income. $\mathrm{\$80,000}-\mathrm{\$2,925}=\mathrm{\$77,075}$
• Estimated Illinois income tax: Multiply taxable income by the flat tax rate of 4.95%. $\mathrm{\$77,075}\times 0.0495=\mathrm{\$3,815.21}$

Illinois effective tax rate: $3,815.21 divided by $80,000 of household income equals 4.77%, rounded. The estimated state income tax rounds to $3,815 in the comparison table.

Illinois marginal tax rate: 4.95%, the rate applied to each additional dollar of Illinois taxable income in this example.

Step-by-Step Example 2: Married Filing Jointly

Now let's apply the same calculation to a married couple filing jointly. Each spouse earns $80,000 with a combined household income of $160,000. The 2026 Illinois personal exemption is $2,925 for each spouse, or $5,850 combined.

• Taxable income: Subtract the combined personal exemptions from household income. $\mathrm{\$160,000}-\mathrm{\$5,850}=\mathrm{\$154,150}$
• Estimated Illinois income tax: Multiply taxable income by the same flat tax rate of 4.95%. $\mathrm{\$154,150}\times 0.0495=\mathrm{\$7,630.43}$

Illinois effective tax rate: $7,630.43 divided by $160,000 of household income equals 4.77%, rounded. The estimated state income tax rounds to $7,630 in the comparison table.

Illinois marginal tax rate: 4.95%, unchanged from the Single example.

Takeaway

Illinois Income Tax Takeaways

A flat tax rate applies to taxable income: Illinois's 4.95% rate does not necessarily apply to the entire paycheck. In these examples, the personal exemption reduces the amount of income subject to state tax.

Equal income per person produces the same tax per person: At $80,000 per person, the joint personal exemption and taxable income are twice the Single amounts. The joint tax is also twice the Single tax before rounding, so this comparison shows no Illinois marriage penalty.

The effective rate shows tax as a share of household income: Both examples produce a 4.77% effective rate, below the 4.95% marginal rate. Results can differ when exemption eligibility, state adjustments, or tax credits change.