Illinois Estimated Tax Payments (2026)
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Reviewed byIsaiah McCoy, CPAIsaiah McCoy is a Certified Public Accountant (CPA) in Miami, Florida with over a decade of experience in tax, accounting, and financial analysis. He holds a Bachelor of Science degree in accountancy and a Master of Taxation degree from Arizona State University. Isaiah has also earned a Master of Business Administration with a finance concentration from LSU Shreveport. Isaiah has worked within several industries, including public accounting (serving clients in the natural resources, real estate, and not-for-profit sectors), higher education, and healthcare. In his free time, he enjoys traveling and watching soccer and is fluent in Spanish.If you're self-employed in Illinois, you likely need to make quarterly estimated tax payments to both the IRS and Illinois Department of Revenue. State payments are generally required in Illinois once you expect to owe $1,000 or more after withholding. Estimate your federal and Illinois quarterly payments below.
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Set up quarterly paymentsFull tax breakdown
Do you have to pay estimated taxes in Illinois?
Yes. If you're self-employed in Illinois and expect to owe $1,000 or more in Illinois income tax for 2026 after withholding, you must make quarterly estimated payments to Illinois Department of Revenue. This is separate from your federal payments. Illinois taxes income at a flat 4.95%.
When are Illinois estimated taxes due in 2026?
Illinois's 2026 quarterly payments are due April 15, June 15, September 15, and January 15, in four equal installments, on the same calendar as your federal payments.
Q1, April 15, 2026
Q2, June 15, 2026
Q3, September 15, 2026
Q4, January 15, 2027
How much should you set aside for Illinois estimated taxes?
Plan to set aside 25% to 30% of your net self-employment profit to cover federal and Illinois taxes combined, then confirm the exact amount with the calculator above. On $50,000 of net freelance profit, federal self-employment tax alone is about $7,065 (15.3% on 92.35% of your earnings). On top of that you'll owe federal income tax and Illinois income tax, up to about $2,475 at Illinois's flat rate before deductions.
How do you avoid a Illinois underpayment penalty?
To avoid a Illinois underpayment penalty, pay the smaller of 90% of your 2026 Illinois tax or 100% of your 2025 tax, in four on-time installments. Paying the full amount late doesn't help; each installment has to be on time. You can estimate a federal underpayment penalty here.
What deductions lower your Illinois estimated taxes?
Because estimated taxes are based on your net profit, every business write-off you claim lowers what you owe each quarter. Common deductions for 1099 workers, reported on Schedule C, include the home-office deduction, car mileage, phone and internet, software, and supplies. You can also deduct half of your self-employment tax, and the federal Qualified Business Income (QBI) deduction can remove up to 20% of your qualified business income, which flows through to your Illinois return in most states.
Keeper's 1099 tax calculator estimates your bill after deductions, and our write-off guides list the deductions for your line of work.
Note: Figures are current for the 2026 tax year and are for planning, not tax advice. Confirm the details with the Illinois Department of Revenue before you file.
How to file quarterly taxes in Illinois
Filing quarterly in Illinois means two separate payments each period: one to the IRS for federal tax, and one to Illinois Department of Revenue for your state taxes. Here’s how to do it.
- Confirm you need to pay. You owe estimated payments when tax isn’t withheld from enough of your income — 1099 or freelance work, investment income, or other untaxed income. Federal and Illinois run separate tests: the state generally requires estimated payments if you expect to owe $1,000 or more in Illinois tax after withholding and credits, subject to its safe-harbor rules.
- Calculate your federal estimate. Use the Form 1040-ES worksheet (or tax software). Estimate your full-year income, add your federal income tax and self-employment tax, subtract anything already withheld from a paycheck, and split the rest across the year. The estimate at the top of this page gives you a starting number.
- Calculate your Illinois estimate separately. Work out your Illinois amount on its own using Form IL-1040-ES. Don’t just send part of your federal payment to the state — the Illinois calculation is separate, based on your Illinois income tax, credits, and any Illinois withholding.
- Pay the IRS. Pay through IRS Direct Pay (or EFTPS) and choose the estimated tax / Form 1040-ES option. Select tax year 2026 and save the confirmation number. This money counts only toward your federal taxes.
- Pay Illinois separately. Make a second payment to MyTax Illinois and select the Form IL-1040-ES estimated payment for 2026. Save that confirmation too. This money counts only toward your Illinois taxes.
- Repeat on each deadline. For 2026, federal estimated payments are due April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027. Illinois uses those same four dates.
Steps reflect 2026 rules and are for planning, not tax advice.
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Get started freeFrequently asked questions
Yes, if you expect to owe $1,000 or more in Illinois tax for 2026 after subtracting withholding and credits.
April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027.
Illinois uses a single rate of 4.95% for 2026.
Pay the lesser of 90% of your 2026 Illinois tax or 100% of your prior-year tax, in timely installments.
Quarterly taxes by state
Hover a state to see its top income tax rate and how its quarterly payments work.