Iowa Code § 46.20: Declaration of candidacy.

At least one hundred four days before the judicial election preceding expiration of the initial or regular term of office, a judge of the supreme court, court of appeals, or district court including district associate judges, full-time associate juvenile judges, or full-time associate probate judges, or a clerk of the district court who is required to stand for retention under section 602.1216 may file a declaration of candidacy with the state commissioner of elections to stand for retention or rejection at that election. If a judge or clerk fails to file the declaration, the office shall be vacant at the end of the term. District associate judges, full-time associate juvenile judges, and full-time associate probate judges filing the declaration shall stand for retention in the judicial election district of their residence.