You can charge more or credit a user on a payment with in Optix. To add a new charge or to add a credit to an invoice:
Go into Invoices and select the invoice you wish to alter
Click Add item at the bottom of the invoice
If it's a charge: Type in a description, quantity, cost per unit (before tax), and the tax rate for the charge
If it's a credit: Type in a description and the credit amount
Click the blue button ‘Add [moentary amount]’ or ‘Add credit’ at the bottom right of the pop-up window to save changes
Need more info on Invoices?