Indiana Code Title 36. Local Government § 36-9-37-20

Sec. 20. (a) If any principal and interest, or an installment of principal and interest, is not paid in full when due, the municipal fiscal officer shall enforce payment of the following:

(b) If payment is made after a default, the municipal fiscal officer shall also collect a penalty of interest on the delinquent amount at one-half ( 1/2 ) the rate prescribed by IC 6-1.1-37-9(b) for each six (6) month period, or fraction of a six (6) month period, from the date when payment should have been made.