Filing Your Illinois Tax Return for 2019: Complete Instructions for Individuals and Businesses

Filing the correct year’s tax return for Illinois is essential to ensure accuracy in reporting income, claiming eligible deductions or credits, and avoiding unnecessary penalties. For the 2019 tax year, Illinois taxpayers must use the proper forms and follow state-specific rules that may differ from federal requirements. Whether you are filing on time, submitting a late return, or amending an earlier filing, knowing how to file your Illinois tax return for 2019 helps ensure you comply with state tax laws.

This guide is designed for many taxpayers, including individuals, sole proprietors, and small business owners who had income from Illinois sources during 2019. It also applies to part-year residents and nonresidents who must file based on their Illinois base income or federal income tax return status. By addressing the needs of different filing situations, this resource ensures taxpayers understand their obligations and options when completing the individual income tax return.

Following a structured, step-by-step process can simplify what might otherwise be a complex task. In the sections, you will find clear explanations of the required forms, such as the Illinois Form IL-1040, detailed instructions for reporting income and claiming exemptions, and guidance for submitting your return electronically or by mail. With the proper preparation, you can complete your filing accurately, take advantage of available tax credits, and meet all deadlines for your 2019 Illinois tax return.

Overview of Illinois State Income Tax for 2019

Who Needs to File

Illinois requires taxpayers to file a 2019 Illinois individual income tax return if they meet specific criteria. Filing obligations depend on residency status, income level, and whether a federal income tax return was required.

• Full-year Illinois residents must file Form IL-1040 if they were required to file a federal return or if their Illinois base income exceeds their Illinois exemption allowance, even if they were not required to file federally.
  
  
• Part-year residents must file Form IL-1040 and Schedule NR if they earned income while living in Illinois or from Illinois sources while living elsewhere.
  
  
• Nonresidents must file if they have earned enough Illinois-sourced income to incur Illinois tax liability.
  
  
• Dependents must file if their Illinois base income exceeds $2,275 or if they wish to receive a refund of Illinois income tax withheld.

Income Thresholds and Tax Rate

Illinois uses a flat income tax rate of 4.95% for all taxpayers, regardless of income level. For the 2019 tax year, exemption amounts increased, providing additional relief for some filers:

• Single filers: $2,275
  
  
• Married filing jointly: $4,550 (if both spouses qualify)

These exemption amounts apply when income is within certain limits. High-income taxpayers with federal AGI over $250,000 (single) or $500,000 (married filing jointly) are not eligible for these exemptions.

Key Changes for 2019

Several notable updates affected Illinois taxpayers for the 2019 tax year:

• Estimated payment threshold increase – The minimum threshold for required estimates rose from $500 to $1,000.
  
  
• Research and Development Credit Extension—This credit was extended through tax years ending before January 1, 2027.
  
  
• New Data Center Construction Employment Tax Credit—A new credit was introduced for qualifying data center projects that meet specific employment and investment criteria.
  
  
• Wagering and gambling winnings allocation—Winnings from Illinois sources had to be allocated to Illinois for tax years ending on or after December 31, 2019.

Filing Deadlines and COVID-19 Extensions

The standard due date for 2019 Illinois tax returns was April 15, 2020. However, for most taxpayers, due to the COVID-19 pandemic, Illinois extended the filing and payment deadline to July 15, 2020. This extension aligned with the federal government’s decision to postpone the due date for the 2019 federal tax return, offering additional time to file and pay without penalties or interest.

Illinois Tax Forms You’ll Need

Accurately completing your 2019 Illinois individual income tax return begins with gathering the correct forms. All taxpayers use the primary form, but many situations require additional schedules to report income, claim credits, or account for residency status.

Main Form

Form IL-1040 – Individual Income Tax Return
This is the primary form for reporting your Illinois income tax. All full-year residents, part-year residents, and nonresidents who meet filing requirements must use this form. It incorporates federal income tax return information to determine Illinois base income, exemptions, and tax dues.

Common Supporting Schedules and Forms

Depending on your circumstances, you may need to complete one or more of these schedules. When applicable, each schedule must be attached to your IL-1040.

• Schedule NR—Nonresident and Part-Year Resident Computation: This form calculates the Illinois tax on Illinois-sourced income for nonresidents and part-year residents.
  
  
• Schedule ICR—Illinois Credits: Use this schedule to claim the property tax and K-12 education expense credit. These credits reduce your tax liability and may require proof such as receipts or payment records.
  
  
• Schedule IL-WIT – Illinois Income Tax Withheld: This form verifies Illinois income tax withheld from wages, pensions, or other sources. You must attach all W-2s, 1099s, and other withholding statements when claiming this credit.
  
  
• Schedule M – Other Additions and Subtractions: This schedule reports additions to or subtractions from your federal adjusted gross income. Examples include retirement income subtractions, federally tax-exempt interest, or specific business income adjustments.
  
  
• Schedule IL-E/EIC–Earned Income Credit: This schedule calculates the Illinois credit for taxpayers who qualify for the federal Earned Income Credit and determines dependent exemptions.
  
  
• Schedule CR—Credit for Tax Paid to Other States: This form allows residents and part-year residents to claim a credit for income tax paid to another state on Illinois-sourced income.

Having the correct forms ensures your Illinois tax return is complete and accurate. In the next section, we will walk through the step-by-step process of completing your 2019 return, from gathering documents to applying for eligible tax credits.

Step-by-Step Instructions to Complete Your Illinois 2019 Tax Return

Completing your 2019 Illinois individual income tax return requires following each step carefully to ensure accuracy, avoid delays, and claim all credits you are entitled to. The process below follows the sequence of Form IL-1040 and uses information from your federal income tax return to determine your state tax obligations.

Step 1 – Gather Required Documents Before You File Your Illinois Income Tax Return 2019

Before beginning, you should collect every document you need for your federal and Illinois filings. Illinois starts its calculation with information from your federal income tax return, so ensuring that your federal forms are correct will help prevent errors in your state return.

You should have:

• Your federal tax return (Form 1040 or 1040-SR) for 2019 should be completed and ready to reference. Illinois uses federal adjusted gross income as the starting point for state tax calculations.
  
  
• All W-2 forms from employers that report your wages and the Illinois income tax withheld during the year.
  
  
• All relevant 1099 forms include 1099-INT for interest, 1099-DIV for dividends, 1099-R for retirement distributions, and 1099-MISC for miscellaneous income.
  
  
• Include Illinois withholding statements from pass-through entities, such as Schedule K-1-P for partnerships and Schedule K-1-T for trusts and estates.
  
  
• If you plan to claim the property tax credit in Illinois, property tax receipts can reduce the income tax you owe.
  
  
• K-12 education expense receipts if you intend to claim the education expense credit for qualifying costs.
  
  
• Records of estimated tax payments made to Illinois in 2019 are essential because these payments will reduce your final tax liability.

Step 2 – Enter Personal Information on Your Individual Income Tax Return

The first section of Form IL-1040 requires accurate identification and filing status details. Completing this section correctly ensures your return is processed without delays.

When filling out this section:

• To ensure that both returns match, provide your full legal name and mailing address exactly as they appear on your federal income tax return.
  
  
• If filing jointly, provide your Social Security number and your spouse’s numbers, as Illinois uses this information to track your income tax return and any refunds.
  
  
• Indicate your correct filing status, such as single, married filing jointly, or head of household, typically matching the status used on your federal tax return.
  
  
• Identify your residency status for 2019: full-year resident, part-year resident, or nonresident, and complete Schedule NR if you did not live in Illinois for the entire year.

Step 3 – Report Income Using Federal Tax Return Data

Illinois bases its income calculations on your federal adjusted gross income (AGI), so the numbers reported here must align with your federal tax return.

To complete this section:

• Enter your AGI from your federal income tax return exactly as it appears to ensure consistency between federal and state filings.
  
  
• Add any federally tax-exempt income, such as municipal bond interest, because Illinois taxes certain income that is exempt at the federal level.
  
  
• Include any required additions reported on Schedule M, such as retirement income recapture, certain 529 plan withdrawals, or other taxable items not included in your federal AGI.
  
  
• Subtract eligible amounts from Schedule M, such as retirement income subtractions or other allowable deductions, to reduce your Illinois base income.
  
  
• The result of these adjustments is your Illinois base income, which is used to calculate your final tax return amount.

Step 4 – Claim Exemptions and the Child Tax Credit (if eligible)

Illinois provides exemptions that lower taxable income, reducing your total tax due.

When claiming exemptions:

• Take the basic exemption of $2,275 for single filers or $4,550 for married couples filing jointly, provided your income is within the eligibility limits.
  
  
• Add any applicable exemptions for taxpayers 65 or older by December 31, 2019, and for the legally blind.
  
  
• Use Schedule IL-E/EIC to calculate dependent exemptions, ensuring you include all qualifying dependents listed on your federal income tax return.
  
  
• Although Illinois has no separate child tax credit, properly listing dependents on your federal return ensures they are counted in your state return for exemption purposes.

Step 5 – Calculate Your Illinois Income Tax Return Amount

This step determines the tax owed before applying credits.

To complete the calculation:

• Residents should multiply their net income by the 4.95% flat income tax rate to determine the Illinois tax due.
  
  
• Part-year residents and nonresidents must use Schedule NR to calculate Illinois tax based solely on Illinois-source income.
  
  
• If you claimed investment tax credits in prior years and the qualifying property was sold or disposed of within 48 months, complete Schedule 4255 to determine any required recapture.

Step 6 – Apply Tax Credits to Your Income Tax Return

Tax credits directly reduce the amount of tax you owe and can significantly affect your final balance due.

For 2019, you may qualify for:

• The Illinois Property Tax Credit is available if you paid eligible property taxes on your primary residence, with amounts entered from property tax receipts.
  
  
• You may claim the K-12 Education Expense Credit if you have qualifying education-related expenses for your dependents backed up by detailed receipts.
  
  
• If you also qualify for the federal version, the Earned Income Credit is calculated using Schedule IL-E/EIC.
  
  
• The Credit for Tax Paid to Other States is available if you are an Illinois or part-year resident who paid income tax to another state, calculated on Schedule CR.
  
  
• If your business activities meet the state's eligibility criteria, you can receive business-related credits, such as the Research and Development Credit.

When claiming credits, attach all required schedules, proof of payment, and supporting documentation to avoid delays in processing your income tax return.

Common Mistakes to Avoid

Even a small error on your Illinois income tax return can delay your refund, increase your tax due, or trigger a notice from the Illinois Department of Revenue. Awareness of common filing mistakes will help you complete your return accurately the first time.

• Using the wrong year’s forms can cause incorrect calculations and potentially result in your return being rejected. Always confirm that you are using Illinois Form IL-1040 and any schedules specifically for the 2019 tax year.
  
  
• Entering incorrect Social Security numbers can prevent the Illinois Department of Revenue from matching your return with IRS records. Before submitting your tax return, ensure the numbers for you, your spouse, and any dependents are correct.
  
  
• Failing to include required schedules may result in the state disallowing deductions or credits. Attach all necessary forms, such as Schedule ICR for tax credits or Schedule NR for nonresidents and part-year residents.
  
  
• Overlooking residency status requirements can lead to inaccurate tax reporting. If you lived in Illinois for only part of the year or earned Illinois-source income as a nonresident, you must complete Schedule NR to calculate the correct tax amount.
  
  
• Making calculation errors can result in paying more tax than necessary or owing unexpected amounts. Use tax software, a qualified tax professional, or carefully review your math to ensure every figure on your income tax return is correct.

How to File Your Illinois 2019 Tax Return

You can file your 2019 Illinois tax return electronically or by mailing a paper return. Your chosen method may affect how quickly your return is processed and when you receive a refund or apply refundable credits.

Electronic Filing (Recommended)

Filing online through MyTax Illinois is the fastest and most secure method for submitting your tax return. Anyone who pays taxes in Illinois can use this free service, regardless of income level. You can keep track of your filing status in real time with electronic filing, which also lowers the chance of making mistakes by checking for them before you submit.

If you are expecting a refund, you can choose direct deposit to have the funds sent directly to your bank account, typically within one to two weeks. Filing electronically also allows you to claim eligible qualified education expenses and other credits without mailing physical receipts, as long as you retain those receipts for your records.

Taxpayers who prefer assistance may file electronically with the help of a tax professional or by using approved tax preparation software. Either option ensures that the filing complies with the current year's rules and requirements for Illinois.

Paper Filing

If you file by paper, download and print the correct 2019 forms from the Illinois Department of Revenue website. Make sure to include all schedules and attachments before mailing. The correct mailing address depends on whether you are sending a payment with your return:

Without payment:
Illinois Department of Revenue
PO Box 19041
Springfield, IL 62794-9041

With payment:
Illinois Department of Revenue
PO Box 19027
Springfield, IL 62794-9027

When filing by mail, keep copies of all documents for your records. If you have questions about the process, you can contact the Illinois Department of Revenue directly by phone or through their online help portal.

How to Make a Payment

Paying the correct amount on time is critical in completing your 2019 tax return for Illinois. Pay by the original due date, even if you filed for an extension, to avoid penalties and interest.

Payment Deadlines When You File Your Illinois Tax Return 2019

For the 2019 tax year, payments were originally due April 15, 2020. Due to the COVID-19 extension, the state moved the payment deadline to July 15, 2020. This extension matched the federal deadline, allowing taxpayers additional time to submit their payments without penalty. If you still owe tax for 2019, you should pay as soon as possible to reduce interest charges.

Electronic Payment Options Linked to Your Federal Income Tax Return

MyTax Illinois allows you to pay directly from your checking or savings account at no cost. You can also pay by credit or debit card through approved payment processors, which charge a small convenience fee. These online systems provide immediate confirmation and help ensure your payment is credited to the correct tax year. Electronic payment is the fastest way to update your account after filing your federal and Illinois income tax returns.

Traditional Payment Methods

You may also pay by check or money order payable to the “Illinois Department of Revenue.” On the payment, include your Social Security number, the tax year (2019), and your daytime phone number. Mail it along with Form IL-1040-V, the payment voucher, to the address listed on the form. You can also personally pay at an Illinois Department of Revenue regional office.

Estimated Tax Payments

If you expect to owe more than $1,000 in Illinois income tax after subtracting withholding and credits, you must make estimated tax payments for the current year. Use Form IL-1040-ES to calculate and submit quarterly estimated payments. Making timely estimated payments can help you avoid underpayment penalties in the future.

How to Track Your Refund or Balance Due

After filing your 2019 Illinois income tax return, you can monitor the status of your refund or confirm any balance due using tools provided by the Illinois Department of Revenue.

Refund Status Tools

The “Where’s My Refund?” feature on MyTax Illinois is available 24/7 and provides the most up-to-date information. To check your status, you will need your Social Security number, the exact refund amount, and the tax year. Refund information is updated daily, so you can track progress from the time your return is received.

Processing Times

Processing speed depends on the filing method. Electronic filing with direct deposit typically delivers refunds in 7–14 days. E-filing with a paper check can take 6–8 weeks. Paper-filed returns may require 12–16 weeks for processing.

Balance Due Inquiries

If you owe tax, log in to MyTax Illinois to view your balance, see payment history, or make additional payments. You may also call the Illinois Department of Revenue for account assistance. Your federal income tax return and Illinois return information will help staff provide faster service.

Final Filing Checklist

Before submitting your 2019 Illinois tax return, verify that every section is accurate and complete. Ensure your federal income tax return is finalized, as Illinois uses figures from that return to determine your state tax calculation. Confirm that all income sources, deductions, and credits have been reported correctly, and that your filing status and residency details match your actual circumstances for 2019.

Attach all required schedules, such as Schedule ICR for credits and Schedule NR for part-year or nonresident filings. Include every W-2, 1099 form, and any documents supporting the credits you claim. If you owe taxes, select your payment method and complete Form IL-1040-V when sending a payment. If you expect to receive a refund, ensure your direct deposit information is correct. Retain copies of your return, payment confirmations, and supporting documents for at least four years for your records.

Frequently Asked Questions (FAQs)

What should I do if I missed the 2019 filing deadline?

If you missed your 2019 Illinois tax return deadline, file as soon as possible to limit penalties and interest. You can avoid the late-filing penalty by filing your return, even if you cannot immediately pay the entire amount. You may arrange a payment plan with the Illinois Department of Revenue to address any remaining balance.

Which deductions and credits are most commonly missed?

Taxpayers often overlook the Illinois property tax credit, the K-12 education expense credit, and certain retirement income subtractions. Some also forget to claim the earned income credit if they qualify federally. Reviewing your federal income tax return alongside Illinois-specific credits can help identify opportunities to reduce your tax liability and increase your refund.

Can I file jointly if I moved during the year?

Your ability to file jointly depends on your residency status. You can file jointly if both spouses are Illinois residents for the entire year of 2019. You can file separately or jointly for mixed residency situations, but joint filing may require treating both spouses as full-year Illinois residents for tax purposes.

How are military members’ Illinois taxes handled?

Military members keep their state of legal residence regardless of where they are stationed. If Illinois is your legal residence, you must file on all income, even if earned outside the state. Nonresident military members stationed in Illinois generally pay tax only on Illinois-source income that is not exempt under federal law.

Does Illinois have reciprocal tax agreements with other states?

Illinois has reciprocal agreements with Iowa, Kentucky, Michigan, and Wisconsin. These agreements allow residents of those states working in Illinois to pay tax only to their home state on wages, and the same applies to Illinois residents. The agreements apply to wages, salaries, tips, and commissions, but not to other types of income such as gambling winnings.