Iowa Code § 448.10: Wrongful sales — purchaser indemnified.

If, by mistake or wrongful act of the county treasurer, a parcel has been sold on which no tax was due at the time, or when a parcel is sold in consequence of error in describing it within the county system, the county shall hold the purchaser harmless by paying the purchaser the amount due to which the purchaser would have been entitled had the parcel been rightfully sold, and the treasurer and the treasurer’s surety shall be liable to the county to the amount of the treasurer’s official bond; or the purchaser, or the purchaser’s assignee, may recover the amount directly from the treasurer and the treasurer’s surety.