This version of the form is not currently in use and is provided for reference only. Download this version of Instructions for Form IL-1120 for the current year.
This document contains official instructions for Form IL-1120 , Corporation Income and Replacement Tax Return - a form released and collected by the Illinois Department of Revenue. An up-to-date fillable Form IL-1120 is available for download through this link.
Q: Who needs to file Form IL-1120?
A: All corporations doing business in Illinois need to file Form IL-1120.
Q: What is Form IL-1120 used for?
A: Form IL-1120 is used to report income and pay the replacement tax by corporations in Illinois.
Q: When is Form IL-1120 due?
A: Form IL-1120 is due on the 15th day of the 3rd month following the close of the tax year.
Q: Can Form IL-1120 be filed electronically?
A: Yes, corporations can file Form IL-1120 electronically.
Q: What are the penalties for late or incorrect filing of Form IL-1120?
A: Late or incorrect filing of Form IL-1120 may result in penalties and interest charges.
Instruction Details:
Download your copy of the instructions by clicking the link below or browse hundreds of other forms in our library of forms released by the Illinois Department of Revenue.