Any person required to make a prepayment pursuant to Section 6471 who fails to make a prepayment before the last day of the monthly period following the quarterly period in which the prepayment became due and who files a timely return and payment for the quarterly period in which the prepayment became due shall also pay a penalty of 6 percent of the amount equal to 90 percent or 95 percent of the tax liability, as prescribed by that section, for each of the periods during that quarterly period for which a required prepayment was not made.
