How to rectify an amount due or a payment difference that occurs after payment has been taken


Once an order has been paid in cash or by credit card, the grand total of the order can still change causing an outstanding amount against the order.

This will result in a warning, or error message in the back office.

Check what has caused the amount due

To find out what caused the discrepancy, begin by checking the 'Log' tab in the order screen.

Typical causes are:

  1. Parking charges changed automatically based on the difference between the ETD and ATD
  2. Security fees - if these charges are based on the number of departing passengers for example, and this changed after the payment had been taken, there would be a discrepancy
  3. Airport fees -  may vary depending on the departure destination. A difference would be caused if the A/C changed it's destination last-minute
  4. Handling fees - e.g. a night surcharge causes an increase in Handling fees where the ATD falls within night hours when the ETD previously did not

Handling an amount due after departure or checkout

At this point you have the following options in order to resolve the outstanding amount:

  1. Manually override the price for the service(s) that changed since the payment was taken, and revert them back to their original amount. In the above example, you could reset the parking fees to the original charge of 13.76
  2. Add the service ‘payment difference’ to compensate for the difference. Set its unit price to -13.76, in order to reset the amount due back to 0. 
    You can do this if you don't want to charge the customer for the difference. By adding comments to the External/Internal Remarks of this service, you can explain the reasons for this amount to your colleagues/client to avoid any queries in the future.
  3. Take a payment from a card which has been kept on file, and enter the details in FBO One using the "Pay" command in the order screen.
  4. Send the customer an invoice for the remaining balance
Override the price for the services that changed

Click on the service in the Order screen, and select the Edit Service command in the menu on the left, update either the unit price or quantity.

For our example, we restore the quantity from 16 to 8

Note that authorization for the command AllowOverrideUnitPriceAndQuantity needs to be granted to the current user.

Adding the Service ‘payment difference’ to compensate for the difference

An alternative, would be to add a 'PAYMENT DIFFERENCE' service to the order. 


Using a payment difference service, allows you to clearly document on the invoice what happened and why. The amount can be exported to a separate "payment differences" ledger in your accounting system. Adding External remarks will complement the addition of the "Payment Difference" service.

In order to use a payment difference service, a payment difference product has to be created. Best practice, is not to have VAT or any other tax applied to it.

It's calculation priority should be set to a higher number than an order-level surcharge, such as a credit card surcharge. This is to prevent that the surcharge would apply to the payment difference, which would in turn cause again an amount due.

Send the customer an invoice for the remaining balance
You can then generate an invoice for the order, and it will show the grand total, the amount paid, and the amount due.