2023 California Code › Revenue and Taxation Code - RTC › DIVISION 2 - OTHER TAXES › PART 10.2 - ADMINISTRATION OF FRANCHISE AND INCOME TAX LAWS › CHAPTER 4 - Payments and Assessments › ARTICLE 6 - Interest › Section 19101.

19101. (a) If any amount of tax imposed by Part 10 (commencing with Section 17001) or Part 11 (commencing with Section 23001), is not paid on or before the last date prescribed for payment, interest on that amount at the adjusted annual rate established under Section 19521 shall be paid for the period from that last date to the date paid.
(b) For purposes of this article, the last date prescribed for payment of the tax shall be determined under Chapter 4 (commencing with Section 19001), with the application of the following rules:
(1) The last date prescribed for payment shall be determined without regard to any extension of time for payment or any installment agreement entered into under Section 19008.
(2) The last date prescribed for payment shall be determined without regard to any notice and demand for payment issued, by reason of jeopardy as provided in Article 5 (commencing with Section 19081), prior to the last date otherwise prescribed for that payment.
(3) In all other cases in which the last date for payment is not otherwise prescribed, the last date for payment shall be deemed to be the date the liability for tax arises (and in no event shall be later than the date notice and demand for the tax is made by the Franchise Tax Board).
(c) Except as provided in this article:
(1) Interest prescribed under this article on any tax shall be paid upon notice and demand, and shall be assessed, collected, and paid in the same manner as taxes. Any reference in Part 10 (commencing with Section 17001), Part 11 (commencing with Section 23001), or this part (except Article 3 (commencing with Section 19031), relating to deficiency assessments) to any tax imposed by Part 10 (commencing with Section 17001) or Part 11 (commencing with Section 23001) shall be deemed also to refer to interest imposed by this article on that tax.
(2) (A) Interest shall be imposed under subdivision (a) in respect to any assessable penalty, additional amount, or addition to the tax (other than an addition to tax imposed under Section 19131, 19132, or 19164) only if that assessable penalty, additional amount, or addition to the tax is not paid within 15 calendar days from the date of notice and demand therefor, and in that case interest shall be imposed only for the period from the date of the notice and demand to the date of payment.
(B) Interest shall be imposed under this article with respect to any addition to tax imposed by Section 19131 (relating to failure to file a return on or before the due date), Section 19132 (relating to underpayment of tax), or Section 19164 (relating to imposition of the accuracy-related penalty), for the period that:
(i) Begins on the date on which the return of the tax with respect to which that addition to tax is imposed is required to be filed (including any extensions), and
(ii) Ends on the date of payment of that addition to tax.
(3) If notice and demand is made for payment of any amount and if that amount is paid within 15 calendar days after the date of the notice and demand, interest under this article on the amount so paid shall not be imposed for the period after the date of the notice and demand.
(d) This article shall not apply to any failure to pay estimated tax required by Section 19025 or 19136.
(Amended by Stats. 2000, Ch. 863, Sec. 24. Effective January 1, 2001.)