To record a refund for the advance payments received from a customer:
Go to the Sales tab on the left sidebar and select Customers.
Select the customer for whom you want to record a refund.
On the customer details page, click the Unused Credits. A pop-up will appear with the list of unused credits.
Click Excess Payment, and you will be taken to its payment receipt.
Click the More icon and select Refund.
Verify the details, enter a reference number and a description, if required, and click Save.
The refund for the advance payment made by your customer will be recorded.
Books
Simplify accounting
and GST filing.