What is a Mexican customs pedimento: structure, fields, and why it governs your inventory
When a shipment crosses into Mexico, the commercial invoice and the U.S. export filing do not establish its legal status south of the border. That job belongs to the pedimento: the official electronic customs declaration filed with Mexico’s tax and customs authorities.
US procurement and logistics teams often treat the pedimento as “the Mexican broker’s paperwork.” In practice, the pedimento is the master transaction record that feeds the plant’s Anexo 24 inventory control, opens or closes tax-credit balances in the SCCCyG (Anexo 30 / historically Anexo 31), and proves who holds legal custody of consigned materials or tooling. If a line item on the pedimento disagrees with your ERP, customs audits the pedimento first and asks your ERP to explain itself second.
Editorial note. This guide is for general operational orientation and is not legal, tax, or customs advice. Pedimento block layouts, appendices, and filing rules are governed by the Customs Law (Ley Aduanera) and Anexo 22 of the General Foreign Trade Rules (RGCE) in force. Confirm specific declarations with a licensed Mexican customs broker (agente aduanal). Operated independently by Heberey LLC; not affiliated with SAT, ANAM, or any government body.
How a pedimento is built (Anexo 22 blocks)
Every pedimento follows the standardized structure mandated by Anexo 22 of the RGCE. Even if you do not read Spanish fluently, you can audit a pedimento once you know its six functional blocks:
| Pedimento Block | What it declares | Why operations & finance teams must check it |
|---|---|---|
| 1. Header (Encabezado) | Pedimento number (15 digits: year + customs house + broker patent + sequential digits), operation type (IMP / EXP), pedimento code (clave de pedimento), destination/origin code, exchange rate, gross weight, and entry date. | The two-character clave (A1, IN, AF, RT, V1, F4) dictates whether taxes are paid permanently or deferred on a ticking clock. |
| 2. Importer / Exporter Data | Mexican tax ID (RFC), legal name, fiscal address, and CURP (where applicable). | Confirms who is the legal Importer of Record in Mexico. A foreign company’s U.S. EIN cannot occupy the domestic importer field for an IMMEX temporary entry. |
| 3. Supplier / Buyer & Transport | Foreign supplier or buyer ID (Tax ID/EIN), invoice/COVE reference numbers, Incoterm (Apéndice 14), and carrier/container details. | Links the customs declaration to your commercial invoice and the electronic value receipt (COVE). |
| 4. Header Identifiers & Accounts | Program numbers (IMMEX authorization number, PROSEC sector), general identifiers (Apéndice 8), and customs guarantee accounts. | Establishes program standing at the document level. |
| 5. Tax Summary (Cuadro de Liquidación) | General import duty (IGI), customs processing fee (DTA), pre-validation fee (PRV), IVA (16% VAT), IEPS, and the payment form code (Apéndice 13). | Shows whether cash was paid (0 = cash/efectivo) or deferred/credited (21 = IVA/IEPS credit under certification; 6 = pending/deferred). |
| 6. Line Items (Partidas) | Sequential item number, 8-digit tariff code (Fracción Arancelaria) + 2-digit NICO, customs value, UMC (commercial unit & quantity), UMT (tariff unit & quantity), origin/seller country, and line-level identifiers. | This is what loads into Anexo 24 and SAT Data Stage. If quantities or units drift here, the plant’s inventory ledger drifts with them. |
How to read the 15-digit pedimento number
When a broker or Mexican warehouse sends a spreadsheet of open balances, the reference key is a 15-digit string formatted as YY AA PPPP NNNNNNN (for example, 26 24 3999 6001234):
- First 2 digits (
YY): Last two digits of the validation year (26= 2026). - Next 2 digits (
AA): Two-digit code of the customs house (Aduana de despacho from Apéndice 1 of Anexo 22: e.g.,24for Nuevo Laredo,80for Colombia,07for Ciudad Juárez,40for Tijuana,30for Reynosa). - Next 4 digits (
PPPP): The 4-digit license number (patente) of the Mexican customs broker or agency. - Last 7 digits (
NNNNNNN): Sequential document number assigned by that broker for that year (where the first digit of the 7-digit block encodes the year digit).
Knowing this format helps you spot immediately when an ERP receipt was keyed with an internal broker file number or a U.S. entry number instead of the official Mexican pedimento number.
Why line-item units (UMC vs UMT) break IMMEX reconciliation
One of the most expensive misunderstandings between U.S. shippers and Mexican compliance teams happens inside the Partidas block. Every line item on a Mexican pedimento requires two quantities and two units of measure:
- UMC (Unidad de Medida Comercial, Apéndice 7): The unit on your commercial invoice and COVE: for example,
1(Kilo),6(Piece / Pieza),12(Set / Juego), or18(Hundred / Ciento). - UMT (Unidad de Medida de la Tarifa): The fixed unit assigned to that 8-digit tariff classification in Mexico’s tariff schedule (TIGIE).
If your U.S. shipping team invoices copper wire in spools or feet, your Mexican plant’s ERP tracks it in meters, and the Mexican tariff classification requires kilograms as the UMT, the pedimento records the UMT in kilograms. When the SAT’s automated SCCCyG system (Anexo 30 / 31) tracks tax-credit discharges, it reconciles by tariff fraction and fiscal value derived from the pedimento. If a shipping clerk changes the net weight estimate on an export invoice without updating the conversion factor in Anexo 24, the export pedimento (RT) can over-discharge or under-discharge the original import (IN).
Four checks to run on a sample pedimento before scaling shipments
Before you put a new lane or contract manufacturer on autopilot, ask for the full PDF of one validated pedimento (not just the simplified single-page pedimento simplificado or DODA barcode sheet used by the truck driver) and check four things:
- Does the Clave de Pedimento match the commercial deal? Temporary production inputs under IMMEX should enter under
IN, consigned machinery or molds underAF, and permanent purchases underA1. - Are part-level quantities and values reconciled to the COVE? In consolidated pedimentos (pedimentos consolidados), multiple weekly truck crossings (remesas) roll up into one closing pedimento. Verify that every remesa matches the physical warehouse receipts for that week.
- Are fixed assets carrying serial numbers (
Identificador NS)? If the shipment includes machinery, test equipment, or molds, check the line-item observations andNSidentifier in Apéndice 8. Missing serial numbers make customs inspection and eventual return (RT) hazardous. - How is the 16% IVA settled in the Cuadro de Liquidación? Look at the
FP(Forma de Pago) column next toIVA. If the plant holds active IVA/IEPS certification, you will typically see payment form21(credit under certification). If you see0, cash VAT was paid at the border.
Check your pedimento and ERP alignment
Run our interactive checklists to trace how pedimento lines connect to warehouse receipts, Anexo 24, and SCCCyG balances.
Educational tools only; they do not validate official SAT filings.
Frequently asked questions
What is a pedimento in Mexican customs?
A pedimento is the official Mexican customs declaration governed by the Customs Law (Ley Aduanera) and the filling instructions in Anexo 22 of the General Foreign Trade Rules (RGCE). Transmitted electronically by a licensed Mexican customs broker (agente aduanal) or authorized customs representative, it declares the customs regime, the importer or exporter's RFC, tariff classifications, customs value, applicable taxes or deferrals, and non-tariff regulations.
Is the Mexican customs broker legally responsible for everything on the pedimento?
The customs broker transmits and signs the declaration, but legal responsibility for the accuracy of the commercial data, origin claims, valuation, and post-entry regime obligations (such as Anexo 24 inventory control and export return deadlines) stays with the importer of record. Delegating filing to a broker does not transfer the importer's statutory liability.
Why does a US buyer or shipper need to care about the Mexican pedimento?
Because the pedimento sets the legal status of your goods inside Mexico. If you consign raw materials, electronic components, or production tooling to a Mexican plant, the pedimento determines whether those items entered temporarily under IMMEX (codes IN or AF) or definitively (code A1), what unit of measure must be discharged upon export, and whether you can legally recover your tooling later.
Where do IVA/IEPS certification and USMCA preference show up on a pedimento?
They appear as two-letter identifier codes (identificadores from Apéndice 8 of Anexo 22) either in the header block or at the line-item (partida) level, paired with the payment form code (Apéndice 13) in the tax block. For example, TL marks a free-trade agreement tariff preference, while specific tax-credit identifiers and payment form 21 indicate an IVA/IEPS credit applied under certification.
What is the difference between UMC and UMT on a pedimento?
UMC (Unidad de Medida Comercial) is the commercial unit used on the invoice and in your ERP (pieces, rolls, boxes), coded under Apéndice 7 of Anexo 22. UMT (Unidad de Medida de la Tarifa) is the mandatory unit assigned to that tariff classification in Mexico's TIGIE schedule (commonly kilograms, pieces, or liters). Both are declared on every line item, and conversion-factor errors between UMC and UMT are a primary cause of Anexo 24 and SCCCyG balance drift.
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