Instructions for Form IL-1120 Corporation Income and Replacement Tax Return - Illinois

Form IL-1120 Corporation Income and Replacement Tax Return - Illinois

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.

FAQ

Q: What is Form IL-1120?
A: Form IL-1120 is the return form for corporations to file their income and replacement tax in Illinois.

Q: Who must file Form IL-1120?
A: All corporations doing business in Illinois, including S corporations, must file Form IL-1120.

Q: When is Form IL-1120 due?
A: Form IL-1120 is due on the 15th day of the 3rd month after the close of the corporation's tax year.

Q: What taxes are reported on Form IL-1120?
A: Form IL-1120 is used to report corporate income tax and replacement tax in Illinois.

Q: Are there any extensions available for filing Form IL-1120?
A: Yes, you may request an extension to file Form IL-1120, but any tax due must still be paid by the original due date.

Q: What supporting documents do I need to attach to Form IL-1120?
A: You may need to attach federal tax forms, such as Form 1120 or 1120S, and any other required schedules or forms.

Q: Are there penalties for late filing or underpayment of taxes on Form IL-1120?
A: Yes, there are penalties for late filing and underpayment of taxes. It is important to file and pay on time to avoid these penalties.