credit note
noun [ C ]
UK ukus( US credit memo); (also US credit receipt) COMMERCE
a document that a seller gives to a buyer who returns a product, pays too much for something, etc., which the buyer may use at a later time to pay for something else:
Most shops will allow you to make an exchange or offer you a credit note instead of a refund.
Incorrect invoices may need to be adjusted by means of a credit note issued by the supplier.