Your credit or debit card is charged when you place your order. If you order a “fill,” your card will be charged for your total tank capacity. Once delivery is made, your credit or debit card account is automatically credited for any gallons that do not fit in your tank. If you order a specific number of gallons (Example: 200 gallons) your credit or debit card will be charged for the amount of your order. Once delivery is made, your account is automatically credited for any gallons that do not fit in your tank. Either way, you only pay for the number of gallons that you receive.