Ark. Code Ann. § 14-90-1403

If any assessment, or annual installment thereof, levied by a municipal improvement district shall not be paid within the time provided by the city ordinance approving the assessment, the county tax collector shall add thereto a penalty of ten percent (10%) and shall at once return a list of all the property within the district on which the assessment or installment has not been paid to the board of improvement as delinquent.