Cal. Rev. & Tax. Code § 9420
Except for trip permits as provided in Sections 8708 and 60122, all interstate users who choose to obtain an IFTA license from the board shall apply for a license and secure decals for their vehicles. Application for the license and decals shall be made annually on forms prescribed by the board. The application shall be under oath and shall contain that information as the board deems necessary. Upon receipt of the application, and upon payment of any required reinstatement fee, the board may issue to the applicant a license and decals.
The decals issued to the interstate user shall be placed on both exterior sides of the vehicle cab. Failure to display the decals in the required location may subject the interstate user to the purchase of a trip permit. The transfer of decals from one interstate user to another interstate user is prohibited. All decals shall remain the property of the state and may be recalled for any violation of the provisions of the IFTA.
A fee to be determined by the board shall be charged for the annual license and a set of two decals issued prior to and during the calendar year that the license and decal is valid. The board may also prescribe procedures and set a fee for the issuance of a 30-day IFTA temporary license or replacement decals.
Ca. Rev. and Tax. Code § 9420