In multinational groups, the question comes up often: why is a related-party transaction challenged when there is a contract, a CFDI electronic invoice, documented payment, and a transfer pricing study?
The answer is direct: tax audits no longer look only at form. Today, Mexico’s tax authority (the SAT) examines whether the transaction had a business purpose, whether it had economic substance, and whether its consideration was set in line with the arm’s length principle. The analysis is no longer documentary — it is structural.
The Regulatory Framework
Article 5-A of Mexico’s Federal Tax Code (CFF) — the country’s general anti-avoidance rule (GAAR) — empowers the tax authority to recharacterize legal acts that lack a business purpose and generate a tax benefit. The provision incorporates two rebuttable presumptions (iuris tantum): absence of business purpose is presumed when the tax benefit exceeds the expected economic benefit, or when the same objective could have been achieved through fewer acts with a greater tax burden. To apply this provision, the case must be submitted to the joint review panel established under Rule 2.1.50 of the 2026 Miscellaneous Tax Resolution (RMF, Mexico’s annual tax guidance). The GAAR is no longer a dead letter.
In parallel, Articles 76 (sections IX and XII), 179, and 180 of Mexico’s Income Tax Law (LISR) require taxpayers to document related-party transactions consistent with the arm’s length principle and with the corresponding methodology. These are not isolated discussions: purpose, execution, and price are three planes of the same examination.
The CFDI Is Not Enough
For years, the defense rested on formal sufficiency: contract, invoice, bank transfer, technical study. Today that is insufficient. The CFDI — Mexico’s official electronic tax invoice — proves form, not economic reality. Criterion 44/ISR/PI of Annex 3 of the 2026 Miscellaneous Tax Resolution — previously labeled a “non-binding criterion” and now reclassified as an “improper tax practice” — confirms it: deducting services requires proving that the service was actually rendered, supported by Article 27, section I of the LISR and by contradicción de tesis 128/2004 of the Second Chamber of Mexico’s Supreme Court of Justice (SCJN).
Transfer Pricing: Beyond the Range
In transfer pricing, showing that profit falls within the arm’s length range is no longer enough. The 2022 OECD Transfer Pricing Guidelines require accurate delineation of the actual transaction, identifying the functions effectively performed, the assets actually used, and the risks genuinely controlled. Article 180 of the LISR sets a methodological hierarchy: first, the comparable uncontrolled price (CUP) method; only when it proves inappropriate do the other methods apply. Profit must align with where value is created; risk, with whoever controls it; consideration, with whoever holds the real functions, assets, and operational capacity.
The Link Between the Three Pillars
Business purpose answers why the transaction took place. Economic substance demonstrates who did what, with what resources, and under what real control of risk. Transfer pricing examines whether the consideration matches that functional reality. When one of the three pillars fails, the entire defense weakens.
What the Tax Authority Expects to See
Traceability: prior business analyses, emails, meeting minutes, functional reports, deliverables, evidence of the personnel involved, key performance indicators (KPIs), and consistency among accounting records, informative returns — local file, master file, and country-by-country report — and the transfer pricing study. The defense is built through a coherent economic and functional file, from the very origin of the operation.
The Practical Lesson
Being within range is not enough. Group entities must assume only the risks they actually control, receive remuneration consistent with their real functions and assets, and be able to explain the transaction not only on paper, but in its business logic and concrete execution. That is the new trilogy of Mexican tax audits — not as an academic concept, but as a working framework for prevention and defense.
