California Code, Vehicle Code - VEH § 2505

Notwithstanding Sections 2501 and 2502, for the purpose of staggering license renewals subject to this chapter, the commissioner may, during any 12-month period, issue licenses that expire 6 to 18 months from the date of issue.  Subsequent renewal of these licenses shall be for a period of 12 months.  Fees with respect to these licenses for more or less than one year shall be prorated accordingly.

This section applies only to licenses for the transportation of hazardous materials established on or after January 1, 1982.