The secured party, before receiving the money tendered to the party by the attaching or execution creditor or which was deposited with the clerk, shall state by a signed memorandum the amount due or to become due and deliver the same along with the security agreement, unless it has been filed as the financing statement, to the person paying the said amount or the clerk with whom the deposit is made, and the secured party shall only receive the amount so stated to be due, and the surplus, if any, shall be returned to the person making the deposit.
Iowa Code § 626.39