Iowa R. Civ. P. 1.304
The officer serving a writ of attachment or execution shall garnish such persons as the plaintiff may direct who are supposed debtors, or who possess property of the principal defendant. Garnishment shall be effected by a notice served in the manner and as an original notice in civil actions. The notice shall forbid the garnishee from paying any debt owing such defendant, due or to become due, and require the garnishee to retain possession of all property of the defendant in the garnishee's hands or under the garnishee's control, to the end that the same may be dealt with according to law. Unless answers are required to be taken as provided by statute, the notice shall cite the garnishee to appear before the court at a time specified not less than ten days after service and answer such interrogatories as may be propounded, or the garnishee will be liable to pay any judgment which the plaintiff may obtain against the defendant.
Iowa. R. Civ. P. 1.304