Cal. Rev. & Tax. Code § 13210
(a) For gross premiums paid or to be paid on insurance contracts that take effect or are renewed on or after January 1, 1994, every California home state insured as defined by subdivision (f) of Section 1760.1 of the Insurance Code, who effects insurance governed by Chapter 6 (commencing with Section 1760) of Part 2 of Division 1 of the Insurance Code shall pay a gross premium tax of 3 percent charged for the use of the state, less 3 percent of returned premiums that were subject to the tax received by reason of cancellation or reduction of premium.
(1) This section shall not apply to any of the following:
(c) Subdivision (b) shall not apply to interstate motor transit operations conducted between this and other states. With respect to those operations, the tax shall be payable on the entire premium charged on all nonadmitted insurance, less any of the following: