MANZANILLO, September 25 — Mexico’s tax authority and customs service have turned supply-chain scrutiny into what amounts to an invisible export requirement for mineral concentrates, dore bars and other bulk mineral shipments, and the Pacific port of Manzanillo is where that scrutiny bites hardest. The shift is described in a Sept. 23, 2026, analysis by Ruben Cano, a founding partner at his firm. It moves enforcement from a “paperwork checks out” standard to a “prove it actually happened” standard known as tax materiality.
For mining exporters, the practical consequence is blunt: a shipment can be geologically sound, commercially priced and fully paid for, and still sit detained at Manzanillo or Lazaro Cardenas because a contractor’s invoice cannot survive the materiality review.
Three pillars of the regime
The legal foundation rests on three pillars. Article 69-B of the Mexican Federal Tax Code empowers the Servicio de Administracion Tributaria (SAT) to presume a transaction backed by a CFDI — an electronic invoice — is non-existent when the issuer lacks the assets, personnel or infrastructure to have delivered what was invoiced. Those are the so-called 69-B lists, or blacklists of presumed simulated operations.
Article 5-A codifies a “business reason” standard, allowing authorities to disregard transactions lacking economic substance beyond a tax benefit even when technically legal. And Rule 1.4.14 of the Reglas Generales de Comercio Exterior (RGCE) allows the authority to demand photographic and documentary evidence proving an importer or exporter has genuine operational capacity — premises, equipment and staff — as a condition to remain active on the Importers/Exporters registry.
Customs brokers are separately obliged to keep a materiality file on every client they clear goods for. In practice, SAT auditors and customs officials can ask a mining exporter to show, not just declare, that concentrate in a container was genuinely moved from a specific pit, through a specific plant, into a specific truck, with a specific weighbridge ticket and assay certificate, before releasing the shipment or validating the expert pediment.
Why bulk mineral cargo is uniquely exposed
Bulk mineral shipments are uniquely exposed because the final product is fungible, blended, and often changes custody several times between the mine gate and the port. A concentrate lot may pass through a toll-milling facility, a warehousing operator, an assay laboratory and a logistics contractor before reaching a smelter customer — frequently a related party under an intercompany agreement, which invites transfer-pricing scrutiny on top of materiality scrutiny. To satisfy both fronts, mining companies are now building an evidentiary spine around every lot.
That includes mine-to-port traceability files with geological block model reference, mine call factor reconciliation, weighbridge tickets, assay certificates by accredited laboratories, and custody-transfer logs at every handoff point. They are also assembling evidence of contractual substance: toll-processing and offtake agreements with clear terms, a communications trail with shipping instructions and laboratory correspondence demonstrating active management, and photographic and site evidence, which is now expressly contemplated under the rules.
What to watch next is whether the materiality file becomes a routine line item in Mexican mining logistics costs, and whether exporters moving concentrate through Manzanillo and Lazaro Cardenas can keep cargo flowing while their contractors’ paperwork holds up.
