Once invoices are paid, sometimes you need to issue a partial refund. You can issue a partial refund as many times as you need until the invoice has been fully refunded.
To issue a partial refund
Go to your invoices list and head to the Paid tab and Find an invoice that is Paid or Partially Refunded.
Head into the Details and click issue refund.
From this, you can decide to refund the full amount or a partial amount.
Once you submit the refund, you can see the list of previous refunds at the bottom of the invoice page.
Once an invoice has been fully refunded, you can no longer action on it!