Iowa Code § 420.224: Limitation on resale by city.

Property which may be sold at tax sale to any such city shall not be offered at any sale for taxes or special assessments, collectible by such city, while it holds the certificate of purchase thereof or tax deed thereon. Nothing in sections 420.220 through 420.223, this section, or sections 420.225 through 420.229 shall prevent the sale of property for any unpaid taxes collectible by the county.