Cal. Vehicle Code § 5204

(a) (1) Except as provided by subdivisions (b) and (c), a tab shall indicate the year of expiration and a tab shall indicate the month of expiration. Current month and year tabs shall be attached to the rear license plate assigned to the vehicle for the last preceding registration year in which license plates were issued, and, when so attached, the license plate with the tabs shall, for the purposes of this code, be deemed to be the license plate, except that truck tractors, and commercial motor vehicles having a declared gross vehicle weight of 10,001 pounds or more, shall display the current month and year tabs upon the front license plate assigned to the truck tractor or commercial motor vehicle. Vehicles that fail to display current month and year tabs or display expired tabs are in violation of this section. (2) (A) (i) A violation of paragraph (1) shall not be the sole basis for any enforcement action before the second month after the month of expiration of the vehicle’s registration. (ii) Notwithstanding clause (i), if a vehicle is stopped for any other violation of this code, enforcement action for a violation of paragraph (1) may be taken before the second month following the month of expiration. (B) This paragraph shall be operative from July 1, 2024, to January 1, 2030, inclusive. (b) The requirement of subdivision (a) that the tabs indicate the year and the month of expiration does not apply to fleet vehicles subject to Article 9.5 (commencing with Section 5301) or vehicles defined in Section 468. (c) Subdivision (a) does not apply when proper application for registration has been made pursuant to Section 4602 and the new indicia of current registration have not been received from the department. (d) This section is enforceable against any motor vehicle that is driven, moved, or left standing upon a highway, or in an offstreet public parking facility, in the same manner as provided in subdivision (a) of Section 4000. (e) Prior to issuing a citation for a violation of this section, a law enforcement officer shall verify, using available department records, that no current registration exists for that vehicle. A citation shall not be issued for failure to comply with this section against any vehicle that has a current registration on file with the department.