REAL TIME ATM PRE-AUTHORIZED HOLDS
EXPLANATION
When a member does a transaction at an ATM machine, that transaction is posted to his/her account at the exact same time. There is no delay.
When a member uses their ATM card to purchase from a merchant (gas station, department store, drug store, etc.) the merchant will typically verify that the member has sufficient funds to cover the transaction and send thru a Pre-Authorization transaction with a unique Key Code. The actual transaction itself is not transmitted until later, typically the next business day.
HOW A PRE-AUTHORIZATION HOLD WORKS
ATM transactions cannot be returned to the originator if funds are not available at the time the transaction posts. For this reason the credit union typically wants to insure that transactions (share drafts, ACH, Shared Branch, Sybil, Home Banking, counter withdrawals, etc) are not approved which bring the account balance below the amount of the Pre-Authorized transaction before it is posted.
Pre-Authorized holds can be found and changed in Program #5 Option P.

As you can see in the display above, there is a $45 Pre-Authorized Hold with Key Code 0123456789 on the Draft account. It was placed on 5/29/2007 and there are 24 hours remaining in the hold.
IF a transaction with Key Code 0123456789 is posted to the member's account, this hold will disappear.
IF a transaction with this Key Code does NOT post to the member's account within 48 hours, the hold will disappear.
There is a possibility that the merchant will NOT follow procedure, and the actual transaction will come thru with a Key Code that does NOT match the Pre-Authorization. In this instance the Pre-Authorized Hold remains until the 48 hours expires, or it is manually changed to a zero amount by a credit union employee.
SETTING PRE-AUTHORIZATION HOLD PARAMETERS
PROGRAM 47, OPTION G

The fields indicated above allow you to determine what happens when a PRE-AUTHORIZATION is received from a merchant.
Do 'ATM-PRE-AUTHORIZED' have up to 48-HOUR-HOLD on funds availability
If you place a Y in this field, the system will place a Pre-Authorized Hold on the funds.
If you place an N in this field, a hold will NOT be placed, and the funds will remain available to the member. It is possible that the ATM transaction will draw the account balance negative when it posts.
Do 'ATM-REAL-TIME-DEPOSITS' have a 48-HOUR-HOLD on funds availability
If you place a Y in this field, a 48 hour hold is placed on the entire amount of funds deposited at an ATM machine. This allows time for the deposit to be verified and any checks to clear. This hold will disappear when the 48 hours expire.
If you place an N in this field, there is no hold placed on funds deposited at an ATM machine. All funds are immediately available to the member.