Mexican Banking Reference

Everything you need to implement SPEI transfers and withdrawals in Mexico. Understanding these concepts helps you build reliable integrations with the Mexican banking system.

CLABE

CLABE (Clave Bancaria Estandarizada) is Mexico's standardized bank account format for SPEI transfers. It has 18 digits:

• Bank code (3 digits) — identifies the financial institution.
• Branch code (3 digits) — identifies the branch.
• Account number (11 digits) — the account identifier.
• Check digit (1 digit) — calculated with a weighted algorithm.

Example: 012345678901234568, where 012 = BBVA México, 345 = branch, 67890123456 = account, 8 = check digit.

Validate a CLABE

Validate the check digit before you create a withdrawal — it catches most typos and transposed digits before the transfer is sent. The algorithm:

1. Multiply each of the first 17 digits by the weights 3, 7, 1, repeating the cycle.
2. Take each product modulo 10 and add them up.
3. The check digit is (10 - sum % 10) % 10. It must equal the 18th digit.

For 01234567890123456 the sum is 82, so the check digit is (10 - 2) % 10 = 8.

def is_valid_clabe(clabe: str) -> bool:
    if len(clabe) != 18 or not clabe.isdigit():
        return False
    weights = [3, 7, 1]
    total = sum((int(d) * weights[i % 3]) % 10 for i, d in enumerate(clabe[:17]))
    return (10 - total % 10) % 10 == int(clabe[17])

is_valid_clabe("012345678901234568")  # True

A valid check digit only proves the number is well-formed — it doesn't confirm that the account exists or who owns it.

RFC

RFC (Registro Federal de Contribuyentes) is the Mexican tax identifier, mandatory for financial transactions. There are two formats:

• Individual RFC: 13 characters — 4 letters + 6 digits + 3 alphanumeric. Example: MAGR850920XY1.
• Business RFC: 12 characters — 3 letters + 6 digits + 3 alphanumeric. Example: ABC850920123.

SPEI operating times

SPEI operates 24/7 and transfers usually complete within minutes. SPEI itself no longer enforces a business-day cutoff, but individual institutions may add their own restrictions: maintenance windows, anti-fraud security validations, and the Mexican holiday calendar.

For reference, these are typical per-institution processing windows:

Holiday calendar (Mexico)

The following Mexican holidays may affect SPEI processing:

• New Year's Day (January 1)
• Constitution Day (February 5)
• Benito Juárez's Birthday (March 21)
• Easter Week (date varies)
• Labor Day (May 1)
• Independence Day (September 16)
• Revolution Day (November 20)
• Christmas Day (December 25)

Institution codes

Institution codes are assigned by Banco de México (Banxico) and used in the institution field of the beneficiary object when creating withdrawals. Below is the full catalogue of SPEI participants — 97 institutions, matching Banxico's SPEI participant list as of September 25, 2026.

Operational notes:

• BANXICO (2001) is used for internal operations: it can receive SPEI, but not send.
• For banks, the last three digits of the code are the CLABE prefix: 40012 BBVA → CLABE starting with 012.

Next steps