Iowa Code
Chapter 39 - ELECTIONS, ELECTORS, APPOINTMENTS, TERMS, AND OFFICERS
Section 39.8 - Term of office.

39.8 Term of office.
The term of office of all officers chosen at a general election for a full term shall commence on the first day of January following the election which is not a Sunday or legal holiday, except when otherwise provided by the Constitution or by statute; that of an officer chosen to fill a vacancy shall commence as soon as the officer has qualified therefor.
[R60, §462; C73, §576; C97, §1060; S13, §1060; C24, 27, 31, 35, 39, §511; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §39.8]
Governor and lieutenant governor, Iowa Constitution, Art. IV, §15
Judges of supreme and district courts, Iowa Constitution, Art. V, §17