ATM transaction posting can sometimes be delayed when the transaction queue gets backed up due to unusually busy traffic. It can take a few minutes longer than usual to post all waiting transactions, and this could result in a delay in when the transaction appears on the member’s account. This might open up a very short window during which it might appear that the funds already taken are still available.

It’s primarily a timing thing, based on the volume of activity being received at a given moment in time. There are times when both MasterCard and Visa send us large batches of transactions all at once, and this can have an effect on CUs with very high volumes of overall EFT activity, especially near the beginning of the month or when there is a holiday. Once the queue clears, transactions are processed as normal.