You won't be double-taxed. Here's how it works:
The income you earned while working in Hawaii is considered Hawaii-source income, and is taxable by Hawaii.
ALL your income, including that from Hawaii, is taxable by your resident state of California.
Therefore at tax time you must file both a non-resident HI tax return (reporting your income from HI) and your normal CA resident tax return (reporting all your income, including the portion from HI).
You'll be able to take a credit on your CA return for the taxes paid to HI, so you won't be double-taxed.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
