"Do I file returns for CA & Arizona and split my salary based on the time in each state?"
Yes. You must file a part-year resident return for each of the two states. Your earnings as a CA resident are taxable by CA. Your earnings as an AZ resident are taxable by AZ. You became an AZ resident for tax purposes on the day you began living in your new home in AZ.
My answer assumes that your work after the move to AZ was 100% remote, and that you never physically worked in CA after you moved.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
