. "(c) Notwithstanding Subsection (b), if a taxing unit does not make a refund, including interest, required by this section before the 60th day after the date the chief appraiser certifies a correction to the appraisal roll under Section 42.41, the taxing unit shall include with the refund interest on the amount refunded at an annual rate of 12 percent, calculated from the delinquency date for the t" . . .