Iowa Code Title XI. Natural Resources [Chs. 455-485] § 468.73. Sale at par--right to pay

Any person shall have the right to pay the amount of the person's assessment represented by any outstanding improvement certificate, with the interest thereon to the date of such payment, at any time. No improvement certificate shall be issued or negotiated for the use of the drainage district for less than par value with accrued interest up to the delivery or transfer thereof. Every such certificate, when paid, shall be delivered to the treasurer and by the treasurer surrendered to the party to whose assessment it relates.