It works like this:
Your bonus will be taxable by California regardless of your state of residence at the time you receive it. That's because it represents compensation for services you performed in California, thus making it "California-source" income. CA can tax non-residents on California-source income.
If you receive it after you become a Utah resident, it will also be taxable by Utah. Utah residents are taxed on all their income, regardless of its source. However, in this situation Utah will grant you a credit for taxes paid to California on income that is taxed by both states. Thus in actuality you won't be double-taxed.
Residency for state tax purposes isn't something you "claim". It's determined by state law. Utah will consider you a resident for tax purposes as soon as you begin living in Utah with the purpose of making it your new permanent home - your domicile in tax terminology. See "Test 3" in this Utah tax reference:
https://incometax.utah.gov/instructions/utah-domicile
You can only have one domicile at a time. Conversely, you become a non-resident of California when you abandon your domicile in California and establish it in a new state.
If you move in 2023, for tax year 2023 you will file a part-year resident tax return in each of the two states. TurboTax can handle this common situation.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
