RTC §30281: (a) Any person who fails to pay any tax, except a tax determined by the board under Article 2 (commencing with Section 30201) or Article 3 (commencing with Section 30221), within the time required sha

(a) Any person who fails to pay any tax, except a tax determined by the board under Article 2 (commencing with Section 30201) or Article 3 (commencing with Section 30221), within the time required shall pay a penalty of 10 percent of the amount of the tax, in addition to the tax, plus interest at the modified adjusted rate per month, or fraction thereof, established pursuant to Section 6591.5, from the date on which the tax became due and payable until the date of payment. (b) Any person who fails to file a return in accordance with the due date set forth in Section 30181 or Section 30183, shall pay a penalty of 10 percent of the amount of the tax with respect to the period for which the return is required. (c) The penalties imposed by this section shall be limited to a maximum of 10 percent of the tax for which the return is required for any one return.