When a customer returns goods or an already-posted invoice needs to be reduced, the correct tool in Odoo is a Credit Note, not deleting the invoice.
Path: Accounting → Customers → Invoices → open the posted invoice → Add Credit Note
- Open the original Posted invoice from the customer invoices list.
- Click the Add Credit Note button at the top of the invoice.
- Choose the refund method: Full Refund to cancel the whole invoice, or Partial to adjust quantities.
- Set the Reason, refund date and journal, then click Reverse.
- For a partial refund, Odoo creates a draft credit note; edit the quantities on the lines to match only the returned goods.
- Verify the 15% VAT is applied on the lines so output tax is reversed correctly.
- Click Confirm / Post; a reversing entry lowers revenue and the VAT payable.
- Optionally click Register Payment to refund the customer or reconcile the credit against other invoices.