Iowa Code § 53.44: Affidavit to be signed and returned.

1. The affidavit on the envelope marked with the affidavit used in connection with voting by absentee ballot under this subchapter by members of the armed forces of the United States need not be notarized or witnessed, but the affidavit on such envelope shall be completed and signed by the voter.

2. In order for the ballot to be counted, the return envelope must be received in the commissioner’s office before the polls close on election day or be clearly postmarked by an officially authorized postal service or bear a postal service barcode traceable to a date of entry into the federal mail system not later than the day before the election, as provided in section 53.17A, and received by the commissioner not later than noon on the Monday following the election.