WA resident - do I need to file CA State Tax Return for less $2k in California W2 income

My son who is a resident of WA worked at his university in California while he was in school and made less than $2k.  The TurboTax software has calculated an amount that he owes California in state income when I look at the CA state income filing site - it says that if an individual with no dependents has income less than $20k, no state return is needed.   Which is right?