What Is a Credit Note
A credit note is the tax document a business issues to reduce, fully or partially, the amount of an invoice it already issued. In SAT's terminology there's no document literally called "nota de crédito" — what actually exists is the CFDI of type Egreso (key "E", meaning "expense" in the SAT catalog), and that's the comprobante everyone in practice calls a credit note. It's used when merchandise needs to be returned, a discount is applied after the original invoice was issued, or a rebate needs to be recognized, without canceling the original invoice.
For any business that invoices in Mexico on a recurring basis, understanding the credit note CFDI correctly avoids two common problems: over-reporting income to SAT for revenue that was actually reversed, and linking documents incorrectly, which creates inconsistencies SAT's own automated validation can flag.
Credit Note CFDI: The CFDI de Egreso Explained
Anexo 20, the SAT technical specification that governs every CFDI, establishes that operations reducing an already-invoiced amount — returns, discounts, rebates — must be documented with a comprobante of type "E" (Egreso). This is the same technical scheme as a regular invoice (type "I", Ingreso): same XML structure, same digital seal, same stamping process through an authorized PAC. The difference sits in the TipoDeComprobante field, which carries "E" instead of "I", and in the fact that a CFDI de egreso is almost always related to one or more prior CFDI de ingreso documents.
That link back to the original invoice isn't optional or cosmetic — it's what lets both SAT and your own accounting understand that the amount no longer counts as final income. Without the correct relationship, a properly stamped credit note that isn't correctly linked doesn't hold up well under review.
When a Credit Note Is Issued
There are three scenarios where a business issues a credit note, and all three fall under the same "E" comprobante type:
- Returns. The customer sends back the product, fully or partially, and the business needs to reduce the income it already reported on the original invoice.
- Discounts applied after the invoice. A discount was agreed after the original CFDI de ingreso was issued — for example, an early-payment discount or a volume discount accrued over the month.
- Rebates. The business recognizes an adjustment in the customer's favor without a physical return of merchandise, such as compensation for a defective product the customer decides to keep.
In all three cases the logic is the same: there's a prior income invoice whose amount no longer reflects the reality of the transaction, and the credit note corrects that difference without canceling the original document. Cancellation has its own requirements and consequences, and it isn't always the right tool when the issue is about the amount rather than the transaction never having happened.
Relation Type: 01 vs. 03
When you issue a credit note, the CFDI de egreso must be linked to the source invoice using SAT's c_TipoRelacion catalog. The two codes that apply here are:
- 01 — Credit note for related documents (Nota de crédito de los documentos relacionados). Used for discounts and rebates on a prior invoice, when the adjustment is about the amount and doesn't involve the product physically coming back to the business.
- 03 — Merchandise return on prior invoices or transfers (Devolución de mercancía sobre facturas o traslados previos). Used specifically when the customer returns the product and the business needs to document that physical return.
Picking the right code matters because each one describes a different economic operation to SAT: a discount isn't the same thing as a merchandise return, even though both reduce the invoiced amount. Using the generic "01" for everything, including actual returns, is one of the most common mistakes, and it can create inconsistencies if SAT cross-checks that information against other data points, like inventory records or a foreign trade complement.
What a Credit Note Needs to Include
Beyond the standard tax fields any CFDI carries — issuer and recipient RFC, CFDI use, payment method — a credit note needs:
- UUID of the related CFDI, the fiscal folio of the income invoice being adjusted.
- The correct relation type (01 or 03, depending on the case).
- Payment method, which as a general rule should match the one used on the original invoice, though the method actually used for the adjustment can optionally be recorded as well.
- A clear concept, describing whether it's a return, discount, or rebate, typically using the generic product/service key that corresponds to this kind of movement.
Skipping any of these fields, or entering them inconsistently with the original invoice, is the most common reason a well-intentioned credit note ends up creating more cleanup work than it saved.
Credit Note Example
A typical case: a store invoiced a business customer for 50 units of a product with an income invoice. Two weeks later, the customer returns 10 units because they arrived defective. The store issues a CFDI de egreso linked to the original invoice's UUID, with relation type "03" (merchandise return), for the amount corresponding to those 10 units plus the proportional VAT. The result: the net income reported for that sale now reflects the 40 units the customer actually kept, with no need to cancel or reissue the full invoice.
Another common case is a volume discount: a customer who purchased multiple times in the month hits a threshold that triggers a retroactive discount. Instead of reissuing every invoice, the business issues a single credit note with relation type "01", linked to the relevant invoices, for the total agreed discount amount.
Common Mistakes When Issuing a Credit Note
- Not linking the CFDI de egreso to the original invoice. Without the correct UUID, the credit note becomes a standalone document that doesn't explain anything on its own.
- Using the wrong relation type. Marking "01" when there was actually a physical merchandise return, or the other way around.
- Issuing the credit note with a different payment method with no justification. This creates inconsistencies against the original invoice if the reason for the change isn't properly documented.
- Confusing cancellation with a credit note. When the transaction never actually happened, the correct move is to cancel the original CFDI, not issue a credit note; you can review the full process in our guide on how to cancel an invoice.
- Waiting too long to issue it. The longer the gap between the triggering event and the credit note, the harder it is to reconcile both documents in that month's accounting.
Credit Notes and the Rest of Your Invoicing Process
A credit note isn't an isolated document — it's part of the same workflow that produces your income invoices, your payment complements, and eventually your cancellations. If you want a refresher on what a CFDI is and how stamping works, check our guide on what a CFDI is, and if you need context on the most recent updates to the scheme, see our article on CFDI 4.0. It's also worth reviewing the full picture of tax documents in our guide to CFDI types, where the egreso type is just one of several a business typically issues.
Frequently Asked Questions
What is a credit note in SAT terms?
It's the common name for a CFDI of type Egreso (key "E"), the document SAT uses to record returns, discounts, or rebates that reduce the amount of an invoice already issued.
Are a credit note and a CFDI de egreso the same thing?
Yes. "Credit note" (nota de crédito) is the term a business uses day to day; "CFDI de egreso" is the technical name SAT gives it in Anexo 20. Both refer to exactly the same document.
When do you issue a credit note instead of canceling the invoice?
When the original transaction did happen but the amount needs adjusting: a partial return, a discount agreed after the fact, or a rebate. If the transaction never happened at all, or the invoice has an error that invalidates it entirely, canceling is the correct move.
Which relation type should I use, 01 or 03?
Use "03" when there's a physical merchandise return tied to a prior invoice. Use "01" for discounts and rebates where the adjustment is about the amount, with no product coming back to the business.
Does a credit note require the customer's acceptance?
Not in the same way a cancellation can, which may require the recipient's acceptance depending on the reason. A credit note is stamped and sent to the customer like any other CFDI, with no mandatory acceptance flow through SAT.
If your business issues credit notes manually and you want every return, discount, or rebate correctly linked to its source invoice on the first try, at AISDC we build CFDI invoicing solutions that automate issuing, stamping, and relating your tax documents.