Use an existing credit note against an unpaid invoice for the same customer and currency.
1. Find the credit note
Open Invoicing → Credit Notes, select the customer’s credit note, and check its currency and unused amount.
The credit note editor shows its customer, currency, and available actions.
2. Find an eligible invoice
Choose Apply to Invoice. Select an eligible unpaid invoice in the same business, for the same customer and currency, with matching accounting treatment: both in the books or both outside the books.
3. Enter the amount
Use no more than the available credit or the invoice balance, whichever is smaller. Confirm the application.
4. Check both balances
Reopen the invoice to check the reduced balance. Reopen the credit note to see any amount left for another invoice.