Iowa Code § 468.58: Installment payments after appeal.

When an owner takes an appeal from the assessment against any of the owner’s land, the option to pay in installments whatever assessment is finally established against such land in said appeal shall continue, if within twenty days after the final determination of said appeal the owner shall file in the office of the auditor the owner’s written election to pay in installments, and within said period pay such installments as would have matured prior to that time if no appeal had been taken, together with all accrued interest on said assessment to the last preceding interest-paying date.