Cal. Rev. & Tax. Code § 17031

Any provision of this part which refers to the application of any portion of this part to a prior period (or which depends upon the application to a prior period of any portion of this part) shall, when appropriate and consistent with the purpose of such provision, be deemed to refer to (or depend upon the application of) the corresponding provision of Part 10 of Division 2 of the Revenue and Taxation Code or of such other Personal Income Tax Laws as were applicable to the prior period.