California Code, Revenue and Taxation Code - RTC § 19777.5

(1) For amounts that are due and payable on the last day of the amnesty period, an amount equal to 50 percent of the accrued interest payable under Section 19101 for the period beginning on the last date prescribed by law for the payment of that tax (determined without regard to extensions) and ending on the last day of the amnesty period specified in Section 19731.

(2) For amounts that become due and payable after the last date of the amnesty period, an amount equal to 50 percent of the interest computed under Section 19101 on any final amount, including final deficiencies and self-assessed amounts, for the period beginning on the last date prescribed by law for the payment of the tax for the year of the deficiency (determined without regard to extensions) and ending on the last day of the amnesty period specified in Section 19731.

(3) For purposes of paragraph (2), Sections 19107, 19108, 19110, and 19113 shall apply in determining the amount computed under Section 19101.

(e)(1) Notwithstanding Chapter 6 (commencing with Section 19301), a taxpayer may not file a claim for refund or credit for any amounts paid in connection with the penalty imposed in subdivision (a), except as provided in paragraph (2).

(2) A taxpayer may file a claim for refund for any amounts paid to satisfy a penalty imposed under subdivision (a) on the grounds that the amount of the penalty was not properly computed by the Franchise Tax Board.