Iowa Code § 2.13: Issuance of warrants.

The director of the department of administrative services shall also issue to each officer and employee of the general assembly, during legislative sessions or interim periods, upon vouchers signed by the president, majority leader, and secretary of the senate or the speaker and chief clerk of the house, warrants for the amount due for services rendered. The warrants shall be paid out of any moneys in the treasury not otherwise appropriated.