A very kind but anxious fellow named Tom calls your finance office and informs your team that he just realized he accidentally submitted a donation to your church in the amount of $5,000. He meant for it to be $50. He pleads for an immediate refund of the difference, since he is on a fixed income and a $5,000 charge to his account would create a terrible hardship for him. Your team wants to help the poor chap immediately. You check the records for your online gifts and sure enough, there it is: an online ACH gift from Tom, a new donor, in the amount of $5,000. You quickly come to Tom's rescue and issue a refund through the ACH system to him in the amount of $4,950. Now that you've saved the day, you can move on to more mundane things.
But two days later, you get a notice from your bank that the original $5,000 gift from Tom was rejected due to insufficient funds in his account. So, his original gift of $5,000 is debited from your church's account as a chargeback. You try to call Tom and the number is no longer a working number. After you think about it for a couple of minutes, the reality begins to sink in … you got scammed. You issued a refund for $4,950 of a $5,000 contribution you never actually received.