Materiality and business purpose: the real evidentiary standard — what evidence saves transactions under audit and what no longer impresses anyone

The era when a deduction was defended with an invoice and a transfer ended years ago. The prevailing standard has two stacked tests: materiality — that the transaction happened in the physical world — and business purpose (art. 5-A CFF) — that it had a real economic purpose beyond the tax benefit. Our introductory article explains the concepts; this one answers the question from the trenches: what evidence, exactly, wins?

What no longer impresses anyone

The "simulation kit" — a generic contract + CFDI (the digital tax invoice) + transfer (sometimes round-trip) — is precisely what invoice mills mass-produced, and that is why the authority and the courts discount it to zero: the perfect form no longer proves anything; it proves, at most, that someone knew the form. Nor do these save you: backdated contracts without fecha cierta (a legally verifiable date), deliverables fabricated in batches (the 12 identical monthly reports with the same creation metadata), or the "I paid in good faith" argument when you never once verified the supplier. The standard moved from documents to traces: what a real transaction leaves scattered across the world without meaning to.

The five layers that do win

Layer 1 — The origin of the deal: why you contracted this service and this particular supplier: the documented need (the project, the problem), compared quotes, negotiation emails. It is the business-purpose evidence par excellence: the traces of a real economic decision. Layer 2 — The supplier's capacity: that whoever invoiced could do the work — personnel (their staff, their specialists), assets, facilities, other clients; verified at the time of contracting (a positive compliance opinion, not a 69-B/69 listing) and archived. Layer 3 — The execution: the heart of the file and where cases are won: deliverables with a process — preliminary versions, corrections, back-and-forth operational emails, minutes with agreements, system access, logs, photos with metadata, identified personnel who can testify. A single thread of genuine emails discussing the work is worth more than ten perfect final reports. Layer 4 — The flow and its logic: a payment through the banking system that matches the contract and the CFDI, to the supplier's account, at market prices (a generic service paid at 5× market is a red flag even if everything else exists). Layer 5 — The effect on your business: the after — the software running, the campaign published, the measurable result, the decision made on the basis of the study. Business purpose under 5-A is proven by showing that the transaction changed something in your economic reality.

5-A in practice: the economic benefit versus the tax benefit

Recharacterization under 5-A applies when the tax benefit exceeds the reasonably expected economic benefit — the test that kills paper restructurings and circular transactions. The defense is built beforehand: the contemporaneous business-purpose memo (what was sought economically, what alternatives were evaluated, why this route) is the piece almost no one has and that turns audits around — not because it is magic, but because it shows the economic purpose existed when it was decided, not that it was drafted when the audit order arrived. Firm rule: every significant transaction (restructuring, intangibles, intercompany services, large payments to new suppliers) is born with its five-layer file and its 5-A memo — or it is not born. The cost is hours; the alternative is the tax assessment, a criminal case at the extreme end, and fighting with reconstructed evidence, which the courts can smell a mile away.