One thing to be aware of is that California has very different rules for W-2 employees and independent contractors. If you are a California non-resident employed as a W-2 employee, you only pay CA tax for periods of time you physically work or live in California.
However, if you are an independent contractor (1099), you are required to pay California income tax for any income you earn from clients located in California, even if you never set foot in California yourself.
