@Expat_CPA --
The problem is that your original W-2 probably IS correct, in that it shows the amount your employer actually did withhold and has already sent to the state. So I wouldn't use form 4852.
In your situation I would enter the original W-2 as is, then file a part-year resident return for each of the two states, and allocate your income accordingly. CA will refund any excess amount withheld, and you will have to pay AZ any tax due.
There will be a discrepancy between the state income amounts shown on your W-2 and on your state returns, which you can explain if you are questioned.
I can tell you that it is not at all uncommon for employers to be late to change state withholding when an employee changes residence to another state.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
