If you need to credit your customer, you can add a negative amount to the invoice, which will act as credit and deduct the amount from the invoice. 

How to add a credit amount to an invoice 

Note that the invoice must be in Draft status. If it is not in Draft status, you will need to revert the invoice status; please click here for steps on how to do this. 
  • Navigate to the relevant Invoice, More>Invoices>select the applicable Invoice
  • Select +Add Invoice Total to Invoice

  • Select the Invoice Class the credit relates to.
  • Name the charge Credit.
  • Enter a description of what the credit relates to. 
  • Enter the credit amount in the Income. Ensure the value leads with a minus sign '-'.
  • Click Save.

  • The credit amount will appear on the invoice and be deducted from the invoice total.