For companies accustomed to US bills of lading, Mexico's Carta Porte is often an unexpected requirement. A loaded truck cannot leave the dock while the Carta Porte is missing. The cause is rarely the invoicing software; it is the data: the number of packages loaded, their weight, the code of each product and the vehicle that arrived. That data originates in the warehouse.
This article explains which part of the Carta Porte depends on the warehouse and how to have it ready before loading is complete. It is not tax advice: how to issue and stamp the document is defined by your Mexican tax team and invoicing provider.
What the Carta Porte is and who issues it
In Mexico, every invoice is an electronic document called a CFDI, validated ("stamped") through the tax authority, the SAT. The Carta Porte is a supplement added to a CFDI to cover the movement of goods within the country. The SAT issued it under article 29 of the Federal Tax Code (Código Fiscal de la Federación), and its supplement page lists version 3.1 as in force since July 17, 2024, with catalogs, filling instructions and FAQs.
According to GS1 Mexico, which publishes a standard message for exchanging this data between shippers and carriers:
- The carrier that charges for the freight issues an income CFDI with the supplement.
- The owner of the goods, or an intermediary, issues a transfer CFDI with the supplement when moving its own goods.
In both cases, the issuer needs the data on the goods transported, and that data is held by the warehouse that picked, packed and loaded them.
The data that comes from the warehouse
| Data | Where it comes from in the warehouse | Common risk |
|---|---|---|
| Goods that travel | The picks and packages loaded on the shipment | Reporting what was ordered rather than what was loaded |
| Product code from the supplement's catalog | The product catalog, linked to each item code | Products with no code assigned |
| Quantity and unit code | The pick and the product's unit of measure | Case versus each confusion |
| Weight in kilograms | Each package's weight when it was closed | Catalog weight that ignores box and pallet tare |
| Gross total weight and number of goods | The shipment totals | Totals typed by hand |
| Hazardous material and its packaging | The product record | Products not flagged as hazardous |
| Vehicle, plates and driver | The shipment record at the dock | Data from the scheduled truck rather than the one that arrived |
| Origin, destination and departure time | The warehouse and the outbound document | Estimated departure time that does not match |
Issuer and recipient tax data, tax regimes and stamping belong to the tax team. What the warehouse controls is that the list of goods and the weights match what was loaded. Note that Mexico works in kilograms: a US system that stores pounds needs a conversion before the data reaches the supplement.
Errors that delay departure
Invoicing what was ordered, not what was picked
If the pick had a short and the Carta Porte was issued with order quantities, the document covers goods that are not on the truck. The fix is to issue from the closed shipment, not from the order.
Catalog weights
A product's unit weight in the catalog excludes the box, void fill and pallet. On a multi-ton load, the difference shows on a highway scale. If your packages are weighed when they are closed, use that weight.
Products without a catalog code
Every item needs its product code from the supplement's catalog. Assigning it when the product is created, rather than on shipping day, saves the tax team from researching each code.
A different vehicle than planned
Carriers often send a different truck or driver. If plates and driver were entered when the shipment was scheduled, the Carta Porte goes out wrong. Confirm vehicle, plates and driver when the truck reaches the dock.
Recommended sequence
- Pick and pack with scanning, so quantities are real.
- Close each package with its weight.
- Load by scanning each package, and do not dispatch while one is missing.
- Confirm vehicle, plates, driver and seals at the dock.
- Close the shipment and send its data to the tax team or the invoicing system.
- Issue the Carta Porte with that data and record its folio on the shipment.
- Dispatch.
The Carta Porte is issued after the loaded goods are confirmed, not before.
How Chainlink records it
Chainlink WMS does not issue CFDIs or the Carta Porte supplement; that stays in your invoicing system. What Chainlink records is the warehouse data that system needs.
A shipment groups the picks and pallets leaving in one vehicle, with its warehouse, dock, carrier, vehicle, plates and driver. On the handheld, each package is scanned as it is loaded: a package from another shipment is rejected and a repeated scan is flagged. While packages are missing, the shipment cannot be dispatched unless a supervisor overrides it and writes the reason. The shipment records its seals and, in its documents field, the invoices and the Carta Porte folio. The printed manifest includes the carrier, vehicle, seals and each package with its document and weight. On dispatch, Chainlink sends the shipment.dispatched event to subscribed integrations in plans with webhooks.
Frequently asked questions
Does the warehouse issue the Carta Porte?
Not necessarily. The carrier issues it with an income CFDI, or the owner of the goods with a transfer CFDI. The warehouse supplies the data on what travels: goods, quantities, units, weights and packaging.
Which version of the Carta Porte is in force?
The SAT's supplement page lists version 3.1 as in force since July 17, 2024. Always confirm the current version on the SAT portal before changing your process.
Can the catalog weight be used?
Yes, but the real shipment weight includes boxes, void fill and pallets. The weight of each package recorded at closing is closer to the weight transported.
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