Curious if any institutions utilize the available balance method for calculating overdrafts?

For those that are using this method, how are your clients charged when a signature-based, non-PIN transaction is approved on good funds, but other transactions clear before it does? Are they assessed one or two fees (one when the available balance is negative, and one more when the debit card transaction clears)?

If you are basing any decisions on charging customer fees based on available balance, I suggest you do it very carefully:

https://www.bankersonline.com/penalty/152982