Background: UK citizen, spent a summer as a J1 intern in California. Didn't get a SSN.
So I sent my US federal tax return and ITIN application to the US embassy London. Fairly sure that was the correct thing to do. Now I realize I need to file CA taxes as well (at least, I think I do, as I'm a "part-year resident"?) Do I send a CA tax return to the US embassy London or to Sacramento? Do I need to do another ITIN application?