Cal. Rev. & Tax. Code § 17951

(a) For purposes of computing “taxable income of a nonresident or part-year resident” under paragraph (1) of subdivision (i) of Section 17041, in the case of nonresident taxpayers the gross income includes only the gross income from sources within this state.
(b) Notwithstanding subdivision (a), the gross income of a nonresident taxpayer does not include income not subject to the Personal Income Tax Law (Part 10 (commencing with Section 17001) of Division 2) by operation of the following federal laws:
1. (1) Section 11108 of Title 46, United States Code, relating to compensation for the performance of duties of certain merchant seamen.
2. (2) Section 11502 of Title 49, United States Code, relating to compensation of an employee of a rail carrier.
3. (3) Section 14503 of Title 49, United States Code, relating to compensation of an employee of a motor carrier.
4. (4) Section 40116 of Title 49, United States Code, relating to the pay of an employee of an air carrier.
5. (5) Section 571 of Title 50, Appendix, United States Code, relating to military compensation of service members.