---
title: "Debit memo: definition | Rex glossary"
description: "A document that increases what a customer owes after the original invoice, for example to correct an undercharge or add a fee."
canonical: https://www.rex.inc/glossary/debit-memo
---

# Debit memo

A document that increases what a customer owes after the original invoice, for example to correct an undercharge or add a fee.

A debit memo adjusts an invoice upward without reissuing it. It's used for underbilled quantities, freight or late fees, and to rebill a deduction that turned out to be invalid.

It's the counterpart to a credit memo. Both should reference the original invoice so the customer's AP team can match them.

## Related terms

- [Credit memo A document that reduces what a customer owes, issued for returns, pricing errors, agreed concessions or approved deductions.](https://www.rex.inc/resources/glossary/what-is-a-credit-memo)
- [Invalid deduction A deduction the customer isn't entitled to under the agreement, such as a duplicate claim, an expired discount or a penalty for something that didn't happen.](https://www.rex.inc/glossary/invalid-deduction)
- [Invoice A document a seller issues to request payment, listing what was delivered, the amount owed, the payment terms and the due date.](https://www.rex.inc/resources/glossary/what-is-an-invoice)

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