Revenue and Taxation Code § 17015.5

17015.5.

For purposes of Part 10.2 (commencing with Section 18401) and this part, the term “part-year resident” means a taxpayer who meets both of the following conditions during the same taxable year.

(a) Is a resident of this state during a portion of the taxable year.

(b) Is a nonresident of this state during a portion of the taxable year.