What type of sales transaction reduces the amount a customer owes?

A credit memo is used to reduce the amount a customer owes. It functions as a formal document issued by a seller to a buyer, effectively acknowledging a reduction in the amount due to a variety of reasons such as returns, allowances, or billing errors. When a credit memo is issued, it decreases the outstanding balance on the customer's account, thus directly impacting the customer’s liability.

In contrast, a refund receipt is issued when money is returned to a customer, often after a product return, which can also reduce what the customer owes, but it is typically a monetary transaction rather than a credit on the account. An invoice is a document that indicates what a customer owes for purchased goods or services, and it does not reduce the amount owed. A sales receipt, meanwhile, is a record of a completed sale that signifies payment has been received and does not impact outstanding balances. Thus, when considering transactions that specifically reduce what a customer owes, the credit memo is the most appropriate choice.