Section 7674 Of Article 4. Deficiency Determinations From California Revenue And Taxation Code >> Division 2. >> Part 2. >> Chapter 5. >> Article 4.

. All deficiency determinations, exclusive of penalty, shall bear interest at the modified adjusted rate per month, or fraction thereof, established pursuant to Section 6591.5, from the last day of the month following the close of the monthly period for which the amount or any portion thereof should have been returned until the date of payment.