Who must file Form IL-1120?

You must file Form IL-1120, Corporation Income and Replacement Tax Return, if you are a corporation that

  • has net income or loss as defined under the Illinois Income Tax Act (IITA); or
  • is qualified to do business in the state of Illinois and is required to file a federal income tax return (regardless of net income or loss).

See our Corporation web page for more information. 

If you have additional inquiries, you may submit them to the Questions, Comments, or Request form.