When such money is deposited with the county treasurer, the treasurer shall by mail notify the purchaser at the tax sale, or the latter's assignee if of record, and shall pay to the holder of such certificate the sum of money deposited with the treasurer for that purpose on surrender of the certificate with proper assignment thereon to the board of supervisors, or to the trustees of the district, as the case may be, as trustee for the district.
Iowa Code § 468.162
89 Acts, ch 126, §2 97 Acts, ch 121, §28