Iowa Code § 69.19: Terms of appointments confirmed by the senate.

All terms of office of positions which are appointed by the governor, have a fixed term, and are subject to confirmation by the senate shall begin at 12:01 a.m. on May 1 in the year of appointment and expire at 12:00 midnight on April 30 in the year of expiration, except terms of office of members of the state transportation commission shall begin and expire as provided in section 307A.1A, subsection 1.