Iowa Code § 524.806: Deposit in the names of two or more individuals.

When a deposit is made in any state bank in the names of two or more individuals, payable to any one or more of them, or payable to the survivor or survivors, the deposit, including interest, or any part thereof, may be paid to any one or more of the individuals whether the others be living or not, and the receipt or acquittance of the individuals so paid is a valid and sufficient release and discharge to the state bank for any payment so made.