If the company is not “transacting business” in Illinois, it may not be required to register.
The Illinois Business Corporation Act of 1983 requires any corporation that was not organized in Illinois to register with the Secretary of State before it “transacts business” in Illinois. 805 ILCS 5/13.05. (Certain insurance companies must instead obtain a Certificate of Authority from the Illinois Department of Insurance. 215 ILCS 5/87.)
However, the Act also states that a corporation will not be considered to be “transacting business” in Illinois if it merely maintains bank accounts in the state without otherwise transacting business in the state. 805 ILCS 5/13.75(3).