It is important for California income tax purposes that you make an accurate determination of your residency status. Tax residency must be determined prior to paying a visitor.Residency for tax purposes is different from residency determined for immigration purposes. A California resident is subject to California state income tax on all income regardless of where it is earned. That is, if you spend more than nine months in California in any tax year, you are presumed to be a resident. But the presumption is rebuttable. This form should be completed after filing your federal taxes.