Skip to main content
Taxpayer Answer Center

Quick Links

Information For

About IDOR


Avoid Common Filing Mistakes for Individual Income Tax

Filing electronically is the best way to avoid common, and sometimes costly, mistakes. You can file your Form IL-1040 for free using MyTax Illinois. Once you submit your return electronically, do not mail a copy. If you choose to make a payment via check, use Form IL-1040-V.

Use the following information to assist you in avoiding processing delays and receiving your refund faster.

Use a calculator. Review the entries you made on each line for accuracy and verify your calculations.

Make sure you use the correct Form IL-1040. This return is tax year specific. For the return due April 18, 2017, you should be using the 2016 Form IL-1040.

Do not send multiple Form IL-1040 returns.

Attach all necessary W-2 and 1099 forms to your Form IL-1040

Include all necessary supporting schedules, forms, and attachments with your Form IL-1040

Double check all personal information in Step 1 of Form IL-1040

Complete all lines of Form IL-1040

Verify certain amounts on our website

Important reminders if you are receiving a refund