Cal. VEH § 1651.5

(a) The director may assign or reassign dates for the expiration of registration for a vehicle registered pursuant to this code. The director may establish a registration year for any vehicle consisting of any period from seven months to 18 months, inclusive, with subsequent renewals being required at yearly intervals thereafter. The director shall assign an expiration date of the last day of the calendar month to all trailers and to all motor vehicles subject to additional fees under the provisions of Section 9400. Any vehicle being registered on a quarterly basis shall be assigned or reassigned an expiration date of December 31 for the registration year. The director shall have the authority to exclude from year-round registration any type of vehicle that the director deems appropriate for exclusion.

(b) In order to implement a year-round registration for vehicles registered pursuant to the International Registration Plan as described in Article 4 (commencing with Section 8050) of Chapter 4 of Division 3, the director, on or before January 1, 2009, shall assign or reassign a date for the expiration of registration of those vehicles described in this subdivision and may utilize the applicable practices and procedures set forth under subdivision (a) in order to implement this subdivision.