Hello bookgirl,

A nonresidence tax return is a tax return for a state other than your resident state. In your case it sounds like you'll need to file a nonresident state return since you earned income in Iowa while you were living in California. 

It is also a wise idea to check with your employer in Iowa to verify they did not accidentally withhold state tax in Iowa since you were paying tax in California.

By moving your post to this board I hope tax experts will be able to advise you on additional steps.

I hope this helps.  Please let us know if you have additional questions.