There can be several different fees charged for using an ATM that is not affiliated with your own bank. The top three are an owner's fee, a surcharge and an international transaction fee. The owners fee is charged by the owner of the ATM and can top $4 at some. A surcharge can be charged by your own bank for not using an ATM in their network. And an international fee can be charged if you use an ATM out of your own country.
