Section 169Local Government Code of 1991 (Republic Act No. 7160), Sec. 169

Interests on Other Unpaid Revenues. - Where the amount of any other revenue due a local government unit, except voluntary contributions or donations, is not paid on the date fixed in the ordinance, or in the contract, expressed or implied, or upon the occurrence of the event which has given rise to its collection, there shall be collected as part of that amount an interest thereon at the rate not exceeding two percent (2%) per month from the date it is due until it is paid, but in no case shall the total interest on the unpaid amount or a portion thereof exceed thirty-six (36) months.