If you are working in Nevada, lucky you! You live in one of the nine states with no income tax. On next year's tax return, you will file a California return as a part-year resident. You'll indicate when you were in California, and how much you earned when you were there. Any excess withholding will be refunded. Of course, it would be in your best interest to get your employer to correct your withholding as soon as possible.

On a related note, when people move from a high tax state to a no tax state, and are in your situation, the losing state often challenges the change of residency. If you have permanently moved to Nevada, and are no longer working in California, it is in your best interest to take concrete steps to establish your residency. Signing a lease or buying a home, changing your driver's license, automobile registration, and voter registration, are just a few of the more important steps. And if there's any way to prove that you were also working in Nevada, that is helpful. These things don't get filed with your tax return, but if California demands that you substantiate your change of residency and place of employment, they'll be the key to getting a refund.