How to File Your Illinois Tax Return For 2024: A Step-by-Step Guide

Filing your Illinois state income tax return for 2024 under the Illinois Income Tax Act begins with your federal income tax return, since your adjusted gross income determines your Illinois base income on Form IL-1040. Log into your MyTax Illinois account to review current tax year liabilities, then gather W-2s, 1099s (including retirement income and military pay), property tax statements, and private party vehicle sales documentation. Completing your federal return first ensures accuracy when calculating Illinois additions and subtractions—such as nontaxable retirement exclusions—and helps you avoid requests for identity verification letters from Illinois Department of Revenue’s Audit Bureau.

Small business owners set up as a limited liability company under the Service Occupation Tax Act or as an S-corporation under the Retailers’ Occupation Tax Act also need to gather profit-and-loss reports, details of vehicles bought for business, and receipts for rolling stock exemption or Use Tax Act deductions. These records feed into Form IL-1120-ST and Schedule M, allowing you to calculate replacement tax liability and exclude vehicles subject to special provisions in the Illinois Vehicle Code. Proper documentation prevents audits, minimizes penalties, and streamlines Illinois Department of Revenue compliance.

Illinois applies a flat 4.95% uniform tax rate, and missing the income tax deadline of April 15, 2025, triggers estimated payment penalties and interest at that same rate. If you need more time, request an electronic filing exception or file Form IL-505-I by the deadline—remember that only check payments with the IL-1040-V voucher are accepted at revenue walk-up windows or by mail. In contrast, e-credit card payments remain available through approved processors in MyTax Illinois. Double-check your exemption claimed amounts and payment entries to avoid a final notice and keep your return on track.

Understanding Illinois State Taxes

Who Needs to File?

• Full-Year Residents: If you lived in Illinois for the entire year and had any Illinois state taxes withheld, you must file an IL-1040. Filing ensures your federal tax return matches state reporting under the Illinois Income Tax Act.

• Part-Year Residents: Those who moved into or out of Illinois during 2024 must file using Schedule NR to report income earned while in-state. Accurate reporting avoids underpayment penalties and ensures your adjusted gross income matches your prorated Illinois base income.

• Nonresidents with Illinois-Source Income: If you earned wages, retirement income, or other Illinois‐source income but lived elsewhere, you must file an IL-1040 with Schedule NR. This prevents issues with IDOR’s Audit Bureau and final notice letters.

• Estimated Payment & Withholding Requirements: Taxpayers who expect to owe more than $1,000 after withholding or credits must make quarterly estimated payments. Missing these deadlines triggers the estimated payment penalty, so track payments through your MyTax Illinois account.

Key Numbers for 2024

• Uniform Tax Rate (4.95%): All taxable base income is multiplied by Illinois’s flat 4.95% rate, regardless of your filing status. Understanding this uniform tax rate helps you project liability and avoid surprises at filing.

• Personal Exemption Amount ($2,775): Each exemption claimed on your IL-1040 reduces taxable income by $2,775. Ensure your adjusted gross income calculation mirrors your federal return to claim the full exemption.

• The deadline for filing income tax returns is April 15, 2025. Returns and any balance due must be filed or paid by April 15, 2025, to avoid late-filing penalties. Mark this tax filing deadline in your calendar and prepare for any “final notice” reminders from IDOR’s walk-up windows.

• Extension Deadline (October 15, 2025): Filing an extension using Form IL-505-I allows you until October 15, 2025, to submit your return; however, it does not extend the deadlines for payment. Plan to pay the estimated tax by April 15 to minimize interest.

What’s New for 2024

• New Credits & Expansions: Illinois expanded the Child Tax Credit to 20% of the Illinois EITC for families with children under 12 and broadened the Volunteer Emergency Worker Credit under the Illinois Emergency Management Agency and Office of Homeland Security acts. Businesses can now claim a Quantum Computing Campuses Credit for qualifying investments.

• Form & Security Updates: Schedule M now includes enhanced verification steps for cannabis-related business deductions to combat identity theft, and Schedule IL-E/EITC has been simplified. These updates protect your information at IDOR’s photo-ready revenue walk-up windows and in online filings.

• IRS Direct File Integration: For the first time, eligible taxpayers can complete their federal income tax return through IRS Direct File and seamlessly transfer federal adjusted gross income to MyTax Illinois. This electronic filing exception reduces duplicate data entry and speeds up refund processing.

Forms and Schedules You’ll Need

Main Individual Form: IL-1040

Form IL-1040 is the primary return for Illinois residents, part-year residents, and nonresidents with Illinois-source income. You’ll transfer your federal adjusted gross income from your federal income tax return to Line 1, then report Illinois-specific additions and subtractions to arrive at your Illinois base income. The form calculates your tax liability under the uniform tax rate and applies personal exemptions.

Common Schedules

• Schedule ICR: This schedule claims credits such as the property tax credit, K-12 education expense credit, and volunteer emergency worker credit. Including accurate receipts and certificates here reduces your overall tax under the Illinois Income Tax Act.
• Schedule CR: Use Schedule CR to claim credit for income tax paid to other states on income earned while an Illinois resident. This prevents double taxation and adjusts your Illinois liability based on your federal income tax return.
• Schedule M: Schedule M reports other additions and subtractions, including rolling stock exemptions and cannabis-related business deductions under the Use Tax Act. Completing this schedule ensures compliance with Illinois Vehicle Code provisions and avoids IDOR adjustments.
• Schedule IL-E/EITC: This schedule covers your Illinois exemption claim and the earned income tax credit, including the new 20% Child Tax Credit. Families with low to moderate incomes should gather federal EITC documentation to maximize their credits.
• Schedule NR: Part-year residents and nonresidents use Schedule NR to allocate Illinois‐source income only. Accurately reporting wages, retirement income, and Transportation Network Providers Act earnings here avoids estimated payment penalties and IDOR enforcement.
  
  

Payment, Extension & Amendment Forms

• IL-1040-V: The payment voucher for paper filers, used when mailing a check or money order. Include your Social Security number and tax year on the memo line to ensure proper credit.
• IL-505-I: File IL-505-I by April 15 to request an automatic extension to October 15; note that the form extends only the filing deadline, not payment. Include estimated tax to minimize late-payment penalties.
• IL-1040-X: Use the amended return form if you discover errors after filing. Correct additions, subtractions, or credits and remit any additional tax owed to reduce interest and penalty accrual.

Small Business Return: IL-1120-ST

S corporations and small business corporations file Form IL-1120-ST for replacement tax reporting under the Retailers’ Occupation Tax Act. Gather your federal Form 1120-S, including Schedule K-1s, and report business income, deductions, and estimated payments. Accurate filing prevents penalties and streamlines your compliance with IDOR’s Audit Bureau.

Step-by-Step Instructions to Complete Your Return 

Step 1: Gather Required Documents

• W-2 and 1099 Forms: Collect all W-2 forms from employers and Forms 1099 for interest, dividends, retirement income, military pay, or other miscellaneous income. These support your federal income tax return and establish your adjusted gross income for Illinois under the Illinois Income Tax Act.
• Federal Form 1040: First, complete your federal Form 1040 to determine your adjusted gross income and exemptions claimed. Your Illinois base income on Form IL-1040 is directly tied to Line 11 of your federal return.
• Self-Employment and Business Records: If you operate as a limited liability company or file under the Service Occupation Tax Act or the Retailers’ Occupation Tax Act, gather profit-and-loss statements, estimated payments, and Schedule K-1s from federal Form 1120-S. Include documentation of motor vehicle purchases or private-party vehicle sales if you intend to exclude vehicles subject to the rolling stock exemption.
• Credit and Deduction Receipts: Retain property tax statements for Schedule ICR, K-12 education receipts, charitable contribution acknowledgments, and income tax records paid to other states. If you provide rideshare services, these items help minimize penalties and maximize credits under the Use Tax Act and the Transportation Network Providers Act.
• Prior-Year Returns and Verification Letters: Keep last year’s Illinois return and any identity verification letter from IDOR’s Audit Bureau or revenue walk-up windows. These will help you fill out personal information, avoid final notice issues, and confirm your MyTax Illinois account settings.

Step 2: Complete Your Federal Return First

• Why Federal First Matters: Your federal income tax return sets the foundation for how to file your Illinois tax return. Federal adjusted gross income determines your Illinois base income, which is multiplied by the uniform tax rate of 4.95%.
• Key Lines to Transfer: Note Line 11 (adjusted gross income), Line 12 (standard or itemized deductions), and Line 13 (taxable income). Transfer your federal AGI to Line 1 on Form IL-1040, ensuring consistency with the Illinois Department of Revenue’s requirements under the Tax Act.

Step 3: Fill Out Form IL-1040

• Personal Information Section: Enter your name, address (including Martin Luther King Dr. for Chicago addresses if applicable), and Social Security number exactly as on your federal return. Select filing status, and indicate full-year resident, part-year resident, or nonresident under the Illinois Income Tax Act.
• Income and Additions/Subtractions: Transfer your federal AGI to Line 1. Report Illinois-specific additions, such as military pay not taxed federally and Transportation Network Providers Act earnings, on Line 2. Subtract Illinois-allowed items—rolling stock exemption, tobacco products sold, and other Use Tax Act deductions—on Line 4.
• Tax Calculation and Exemptions: Multiply your Illinois base income by the state’s uniform tax rate (4.95%) on Line 6. Enter exemption claimed amounts ($2,775 per exemption) on Line 8. Subtract exemptions to determine your tax liability in Illinois on Line 10.
• Credits, Payments, and Penalties: On Lines 11–13, apply credits from Schedule ICR, CR, and IL-E/EITC (including property tax and Child Tax Credit). Enter Illinois state taxes withheld, estimated payments, and credit card payments processed online. The difference is your due balance or refund. Calculate any estimated payment penalty on Line 14 if underpaid during the current tax year.

Step 4: Complete Required Schedules

• Schedule ICR (Illinois Credits): Use this schedule to claim property tax credit, K-12 education expenses credit, and Volunteer Emergency Worker Credit. Attach receipts and certificates, and include any campus credit for quantum computing if your small business qualifies.
  
  
• Schedule CR (Credit for Tax Paid to Other States): Report income tax paid to other states on this schedule to avoid double taxation. Include supportive federal 1099s or W-2s showing out-of-state withholding.
  
  
• Schedule M (Additions and Subtractions): Detail additions, like gains from selling vehicles to private parties, and subtractions, such as rolling stock exemptions or use tax payments. Report any wholesale price adjustments you claimed under the Use Tax Act—this ensures you don’t understate your Illinois base income.
  
  
• Schedule IL-E/EITC (Exemption & Earned Income Tax Credit): Claim your full exemption and Illinois EITC. If you are eligible for the new 20% Child Tax Credit, please calculate it here. Attach the federal Schedule EIC for verification.
  
  
• Schedule NR (Nonresident and Part-Year Resident): Allocate Illinois-source income only, including retirement income, military pay, and transportation network providers' earnings. Use the percentage of days lived in Illinois to prorate income correctly.
  
  

By meticulously gathering documents, leveraging your federal income tax return, and completing Form IL-1040 with all necessary schedules, you’ll streamline filing your tax return, minimize penalties, and avoid a final notice from the Illinois Department of Revenue.

How to File Your Return

Electronic Filing via MyTax Illinois

Filing electronically through MyTax Illinois is the fastest, most secure way to submit your income tax return for Illinois. Start by creating or logging into your MyTax Illinois account and completing the identity verification steps. If you encounter an identity verification letter or need an electronic filing exception, follow the prompts in your dashboard to resolve issues before attempting to e-file. Once verified, the system will guide you through entering your adjusted gross income, selecting credits, and uploading supporting schedules.

• Free Electronic Filing: MyTax Illinois does not charge any convenience fees for filing your IL-1040 online. You can submit your return and any payment voucher (IL-1040-V) without worrying about extra costs or third-party processors.
  
  
• Immediate Confirmation: After hitting “Submit,” you will receive an instant acknowledgment of receipt. This confirmation helps you avoid final notice letters from the Illinois Department of Revenue and gives peace of mind that your return is under review.
  
  
• Enhanced Security Features: MyTax Illinois employs multi-factor authentication and encryption to protect sensitive information. These measures exceed what you’d get through paper filing or walk-up window service at revenue walk-up windows.
  
  
• Seamless Credit Card Payments: If you choose to pay by credit card, MyTax Illinois links to authorized processors directly within your account. Note that convenience fees. The application process remains integrated and secure.
  
  

Paper Filing

If you prefer paper filing, use the IL-1040-V voucher and mail your return to the appropriate address. Remember that only check and money order payments are accepted—no cash or credit card payments—so plan to avoid processing delays.

• No Payment Enclosed
  Mail your completed IL-1040 and all schedules (ICR, CR, M, IL-E/EITC, NR) to:
  Illinois Department of Revenue
  PO Box 19041
  Springfield, IL 62794-9041
• Payment Enclosed
  If you owe a balance, include a check or money order payable to “Illinois Department of Revenue” with your IL-1040-V and mail it to:
  Illinois Department of Revenue
  PO Box 19027,
  Springfield, IL 62794-9027
• Only Check Payments: Ensure your check memo line shows your Social Security number and tax year. Credit card payments are not accepted by mail or at revenue walk-up windows when filing on paper.
• Printing and Packaging Tips: Use black or blue ink only, do not staple your schedules, and include copies of all supporting documents. This helps the Illinois Department of Revenue process your return without contacting you for missing items.
• Processing Times: Paper returns typically take 6–8 weeks to process; expect longer timelines if you file close to the income tax filing deadline or claim complex credits like the rolling stock exemption.
  
  

For paper filings sent from Chicago, include attention to the “Office of the Chicago Secretary” on the envelope so local mail handlers route it correctly before it reaches Springfield.

Whether you choose electronic or paper filing, following these steps ensures you meet the income tax deadline, minimize penalties, and maintain accurate records of your current tax year liabilities.

How to Make a Payment

ACH or Debit via MyTax Illinois

Log in to your MyTax Illinois account to authorize a direct debit from your bank with no convenience fees. Payments post immediately, and you’ll receive an electronic confirmation to help you track your current tax year liabilities.

Credit or Debit Card Payments

Although convenience fees apply, you can make payments online or by phone using approved third-party processors. Transactions are processed securely and applied to your balance as soon as they clear.

Check or Money Order with IL-1040-V

Make checks or money orders payable to “Illinois Department of Revenue” and include the IL-1040-V voucher. Only checks or payments are accepted by mail or at revenue walk-up windows, so note your Social Security number and tax year on the memo line.

ACH Credit for Businesses

Businesses can send payments directly from their bank via ACH Credit, which bypasses check handling and convenience fees. This method is ideal for limited liability companies and S corporations to meet estimated payment requirements on time.

Payment Deadlines & Penalty Avoidance

Observe the income tax filing deadline of April 15, 2025, to avoid the estimated payment penalty. Late payments accrue interest at the uniform tax rate. Schedule timely estimated payments in MyTax Illinois to minimize penalties and prevent a final notice from the Illinois Department of Revenue.

We recommend setting calendar alerts or using MyTax Illinois notifications—reminding taxpayers of upcoming due dates is key to avoiding the estimated payment penalty.

Tracking Your Refund or Balance Due 

Refund Tracking

Log in to your MyTax Illinois account and use the “Where’s My Refund?” tool to check your daily status. This IDOR resource provides processing stage updates, so you know when your refund posts to your bank. If you e-filed with direct deposit, expect funds in about four weeks; paper filings take longer and may prompt a final notice or revenue walk-up window inquiry if delayed.

Balance Due Tracking & Payment Plans

To view your current tax year liabilities, sign into MyTax Illinois and review your account balance online. If you can’t pay by the income tax filing deadline, set up an installment agreement directly through your MyTax Illinois account. Timely payment plans help you avoid estimated payment penalties and interest under the Illinois Income Tax Act.

Lost or Damaged Refund Checks

If your refund check is lost or damaged, contact the Illinois Department of Revenue or visit a local revenue walk-up window service with your Social Security number and tax year details. Once your identity verification letter is on file, you can request a replacement or direct deposit conversion.

Final Filing Checklist 

• Match AGI and Exemptions: To avoid a final notice, ensure your adjusted gross income and exemptions claimed on Form IL-1040 mirror your federal income tax return under the Illinois Income Tax Act.
• Include All Schedules: Attach Schedule ICR, CR, M, IL-E/EITC, and NR with W-2s, 1099s, and property tax statements to prevent requests for identity verification letters from IDOR’s Audit Bureau.
• Verify Payment Method: Check your MyTax Illinois account for ACH/debit or credit card payments, or complete the IL-1040-V voucher for only check payments to sidestep estimated payment penalties at the uniform tax rate.
• Keep Confirmations and Records: Save your MyTax Illinois electronic confirmation, paper return copies, and identity verification letters to support inquiries at revenue walk-up windows or before the Informal Conference Board.

Frequently Asked Questions

What if I missed the deadline for filing my income tax?

If you miss the April 15, 2025, income tax filing deadline under the Illinois Income Tax Act, file your federal income tax return and IL-1040 via your MyTax Illinois account as soon as possible. Pay any balance due or estimated payments to avoid the estimated payment penalty and interest at the uniform tax rate. Prompt filing helps you sidestep a final notice from the Illinois Department of Revenue and minimizes fees.

How does the Illinois Department process e-filed returns?

When you use MyTax Illinois to e-file, the Illinois Department cross-checks your federal adjusted gross income and exemptions claimed against IRS records. The system immediately applies Credits, such as property tax and the Child Tax Credit, along with payments, to help reduce liabilities for the current tax year. Secure multi-factor authentication protects your data, and most returns are accepted within 24–48 hours, eliminating the need for identity verification letters or walk-up window service.

How do I report retirement income on my Illinois return?

Report retirement income, including pension distributions and military pay, on Line 2 of Form IL-1040 as Illinois additions. Use Schedule M to subtract any nontaxable retirement exclusions under the Tax Act. Accurate reporting ensures your adjusted gross income aligns with federal figures and prevents an identity verification letter from IDOR’s Audit Bureau. Properly handling retirement income helps you claim exemptions and avoid underpayment penalties.

How do I request an extension to file my Illinois return?

To extend your income tax filing deadline to October 15, 2025, file Form IL-505-I by April 15, 2025, in your MyTax Illinois account. Include any estimated payment to prevent the estimated payment penalty under the Illinois Income Tax Act. This electronic filing exception grants extra time to attach schedules—ICR, CR, M, IL-E/EITC, NR—but does not extend the payment deadline, so plan accordingly.

Can I file jointly if I moved mid-year?

Part-year residents and nonresidents use Schedule NR to report only Illinois-source income—wages, retirement income, and Transportation Network Providers Act earnings—based on days lived in-state. Married couples filing jointly transfer their combined federal adjusted gross income to Form IL-1040, ensuring consistency under the Illinois Income Tax Act. Prorating income correctly helps you avoid underpayment penalties and simplifies follow-up with the Illinois Department. What happens if I discover an error after filing?

Are there special considerations for small business owners?

Retailers registered as a limited liability company or under the Service Occupation Tax Act and Retailers Occupation Tax Act must file Form IL-1120-ST. They must report business income, estimated payments, and credits—such as the quantum computing campuses credit—and handle private party vehicle sales per the Illinois Vehicle Code. Complying with the Transportation Network Providers Act and maintaining accurate records helps minimize penalties and avoid audits by IDOR’s Audit Bureau.