When we’re storing customer details, we send over a $0 or $1 authorization to their bank to verify that the bank will allow their card to be authorized. We reverse this authorization request immediately, without regards to whether or not it is declined. However, it’s possible this $1 authorization will appear on your customer’s bank statement. Please note that this is NOT a charge, and will disappear from your customer’s statement. Some banks take only a few minute to make the authorization request disappear; some banks take a few weeks.
We will always attempt a $0 authorization when we can. American Express does not accept $1 authorization requests, so we will try a $1 request immediately. If the $0 authorization fails, we will try a $1 authorization.