It is normal for states to tax the income you earn in their state. So if you work and Michigan and get Michigan income, then you would normally be expected to file a Michigan Nonresident and Part-Year Resident Schedule (Schedule NR) with your Michigan income tax return. First complete your Federal return. Then work the Michigan return as a non-resident. Then do your California return. I am not completely familiar with all of the details for these states. However, you should expect that the process will give some credit or deduction to prevent double taxation. It is possible that your Michigan withholdings will exceed your Michigan tax. So if that is the case, then you might get a refund from Michigan. You will have to file to get any refund.