As a business owner, I face similar issues myself. I'm sure you already know this but for something like this, you really should consult a lawyer and a tax professional. Having said that, the cleanest and safest way to do this would be to dissolve the current S-Corp and create a new one under a different name. This way there isn't any controversy over ownership. Hopefully you have a partnership agreement that covers the dissolution of your company. If not, you'll need one now. If you incorporate your own S corp in CA, you will have to register in IL as a foreign corporation. If you won't have a physical presence in IL, you will need a registered agent.