Article 2. Interest of California Revenue And Taxation Code >> Division 2. >> Part 8. >> Chapter 5. >> Article 2.

(a) The tax imposed by this part does not bear interest if it is paid prior to the date on which it otherwise becomes delinquent. However, if the tax is paid after that date, the tax bears interest at the rate for underpayment of estate tax provided in Section 6621(a)(2) of the Internal Revenue Code from the date it became delinquent and until it is paid. Interest under this section shall be compounded daily.
  (b) The amendments made by Chapter 323 of the Statutes of 1998 shall apply to delinquent amounts unpaid on or after January 1, 1999, to December 31, 2000, inclusive.

Every payment on the tax imposed by this part is applied, first, to any interest due on the tax, secondly, to any penalty imposed by this part, and then, if there is any balance, to the tax itself.

All interest and penalties provided in this chapter shall be treated and collected in the same manner as taxes.