When a merchant runs a transaction, the amount is assessed a rate and a transaction fee. Generally the rate is an assessment of risk and the transaction fee is a cost for accessing the digital network. When the merchant refunds a transaction, only a transaction fee is charged. The rate is not charged a second time because there is no risk of default, but the transaction fee is still charged because the transaction is transferred via the digital network. Also, understand that the merchant does not get a refund on the original fees when the card was authorized in the first place.