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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. 

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