If you have a 'nexus' in California, you are subject to that tax. Ask me how I came to find that out :)
"Who Must File
Unless exempt under section 501, all domestic corporations (including corporations in bankruptcy) must file an
income tax return whether or not they have taxable income. Domestic corporations must file Form 1120, unless they are required, or elect to file a special return. See Special Returns for Certain Organizations, below"
LLCs have a similar requirement.