California Code, Revenue and Taxation Code - RTC § 19117

(a) The Franchise Tax Board shall include with each notice to an individual taxpayer which includes an amount of interest required to be paid by the taxpayer under this part information with respect to the section under which interest is imposed and a description of how the interest is computed. Upon the request of the taxpayer, the Franchise Tax Board shall also provide a computation of the interest.

(b) This section shall apply to any notice issued after December 31, 2001.