Sec. 18. (a) A claim or suit settled by, or a judgment rendered against, a governmental entity shall be paid by the governmental entity not later than one hundred eighty (180) days after the date of settlement or judgment, unless there is an appeal, in which case not later than one hundred eighty (180) days after a final decision is rendered.
(b) If payment is not made within one hundred eighty (180) days after the date of settlement or judgment, the governmental entity is liable for interest from the date of settlement or judgment at an annual rate of six percent (6%). The governmental entity is liable for interest at that rate and from that date even if the case is appealed, provided the original judgment is upheld.