For years, the unwritten rule was simple: if you had the invoice, you have the deduction. That era is over. Today Mexico’s tax authors (the SAT) can reject a perfectly invoiced deduction if you can’t prove the transaction actually took place. That requirement is called materiality, and understanding it is the difference between audit-proof books and a contingency that can cost you taxes, surcharges and penalties. This article is the foundation: what materiality is, why the CFDI is no longer enough, and what you need to prove that an operation is real.

Materiality and the CFF

Materiality is the ability to demonstrate that a transaction recorded in your books genuinely occurred: that the goods were delivered or the service was rended, that there was a real flow of money, and that the operation has legal support. It isn’t a formality, it’s a evidentiary pillar.

Tellingly, the word “materiality” (materialidad) doesn’t appear expressly in the Federal Tax Code (CFF). It’s obligation is built from several provision that, read together, leave no way out:

• Article 5-A of the CFF – the business-purpose rule. The authority can disregard operation that lack real economic substance.
• Article 69-B of the CFF – empowers the SAT to presume operations are nonexistent when their materiality isn’t substantiated.
• Article 30 of the CFF – requires you to keep your accounting records and the documentation that supports your transactions.
• Article 29 and 29-A of the CFF – the requirements for the CFDI (the form, which on its own is no longer enough).
• Article 27 of the LISR (Income Tax Law) – the requirement for authorized deductions. On top of this sit administrative criteria and case law – such as non-binding criterion 44/ISR/NV, which demands evidence that a service was effectively rendered, beyond the invoice itself. The underlying message of this whole framework is just one: the burden of proof rests on you, the taxpayer.

Why the invoice isn’t enough

The CFDI proves the form of an operation, not its substance. It shows that an invoice was issued, not that there was a real delivery of service behind it. That’s why the SAT changed the question: it no longer reviews only what you invoiced, but what you did and why you did it.

In practice, this means that alongside each significant invoice you need a trail of evidence that tells the full story of the operation: contracts describing the scope, deliverables of reports, emails and meeting minutes, proof of delivery, and payment records with their bank flow. Without that trail, the invoice stands alone – and a lone invoice is, today, a risk.

Nonexistent operations (69-B)

When you can’t substantiate materiality, the operation enters the territory of “nonexistent operations” and that’s where Article 69-B of the CFF comes in. The consequences are not minor:

• Rejections of the deduction and disallowance of the VAT you credited.
• Assessment of tax liabilities with inflationary adjustments, surcharges and penalties.
• Risk of appearing on the SAT’s blacklist as an EFOS or EDOS.
• Joint-and-several liability for directors and legal representatives, and even criminal consequences in serious cases.

If one of your suppliers lands on that list, the problem shifts onto your books. That’s why this topic connects directly with what to do when a supplier is declared an EFOS – a risk we cover in depth in its own article.

Proving a real operation

Demonstrating materiality means answering, with evidence, three questions on three different planes:

Physical existence

Did the operation really happen? The goods were delivered of the service was rendered, and you can prove it with deliverables, reports, logs, photographs or delivery-acceptance records.

Economic existence and business purpose

Was there a real flow and business reason? Article 5-A of the CFF starts from a clear premise: there is no business purpose when the tax benefit outweighs the economic benefit reasonably expected. The expense must be consistent with your line of business and make economic sense beyond saving taxes, backed by bank payments.

Legal existence

Is there legal support? Signed contracts describing the obligations, and a supplier with real operational capacity – infrastructure, personnel and experience – to have provided what it invoiced.

Gathering and organizing this evidence is that’s known as building a materiality file: the record that, when a request arrives, proves on your behalf that each operation was real.

Frequently asked questions

Does materiality apply only to services or also to goods?

It applies to both. Services are the most scrutinized becase they’re harder to prove, but a sale of goods can also be presumed nonexistent if there’s no evidence of delivery.

Since when has the SAT enforced this so strongly?

Scrutiny over materiality intensified with the addition of Article 5-A (business purpose) in 2020 and with recent criteria and case law. Today it’s one of the central focuses of audits.

What happens if I can’t prove an operation?

The risk is the non-deductibility of the expense, disallowance of the credit VAT, and the imposition of tax liabilities with surcharges and penalties, plus the possible presumption on nonexistence under 69-B.

Conclusion

Materiality changed the rules of Mexico’s tax games: invoicing is no longer enough – you have to be able to prove that each operation was real. The good news is that this is manageable – with processes, organized evidence and supplier monitoring – and the company that does it turns a risk into peace of mind. At Cumbre Asesores we help companies in Mexico City, Guadalajara and Yucatan build that protective structure with DYNAMI. if you’re not sure your operations would survive an audit today, let’s talk.