One type of credit memo is issued by a seller in order to reduce the amount that a customer owes from a previously issued sales invoice. For instance, assume that SellerCorp had issued a sales invoice for $800 for 100 units of product that it shipped to BuyerCo at a price of $8 each. BuyerCo informs SellerCorp that one of the units is defective and SellerCorp issues a credit memo for $8. The credit memo will cause the following in SellerCorp's accounting records: 1)  a debit of $8 to Sales Returns and Allowances, and 2) a credit of $8 to Accounts Receivable. In other words, the credit memo reduced SellerCorp's net sales and its accounts receivable. When BuyerCo records the credit memo, the following will occur in its accounting records: 1) a debit of $8 to Accounts Payable, and 2) a credit of $8 to Purchases Returns and Allowances (or Inventory).

Another type of credit memo, also referred to as a credit memorandum, is issued by a bank when it increases a depositor's checking account for a certain transaction.