S-Corps often have only one shareholder. If you're not going to have many ties with IL going forward, and if most of your ties will be with CA, I'd dissolve the IL entity and form anew in CA. That way you avoid the hassle of double annual filings and double state taxes. Note: you'd likely still need to maintain foreign registrations if you plan to "do business" in other states. Just be aware that "doing business" means different things in different states. Please retain counsel if you have any doubt or questions.