Iowa Code § 37.29

All tax anticipatory warrants shall be signed by the chairperson of the commission and attested by the auditor of a political subdivision which owns the hospital with the auditor’s official seal attached thereto, and dated as of the date of sale, and shall not be sold for less than par value. The warrants may be drawn and sold from time to time as the need for funds to carry out the purpose of this chapter arises.