CLABE Validation

CLABE (Clave Bancaria Estandarizada) is Mexico’s standardized bank account number format used for SPEI transfers. This guide explains the validation algorithm and provides implementation examples. CLABE numbers contain four distinct components that can be extracted for processing:

Total length: 18 digits
Bank code: 3 digits (positions 1-3)
Branch code: 3 digits (positions 4-6)
Account number: 11 digits (positions 7-17)
Check digit: 1 digit (position 18)

Here is an example of a CLABE number and a breakdown of its components: CLABE: 012345678901234567

012Bank Code3 digits (positions 1-3)Identifies the financial institution. See Institution Codes.

345Branch Code3 digits (positions 4-6)Identifies the specific branch or plaza.

67890123456Account Number11 digits (positions 7-17)Unique account identifier within the branch.

7Check Digit1 digit (position 18)Validates the entire CLABE using a weighted algorithm.

The first 3 digits of a CLABE correspond to the last 3 digits of the institution code. For example, 012 in the CLABE maps to institution code 40012 (BBVA Mexico).

CLABE Validation Algorithm

The CLABE validation algorithm uses a weighted sum calculation to verify account number integrity. Each of the first 17 digits is multiplied by a specific weight (following the pattern 3, 7, 1 repeatedly), then all products are summed. The check digit is calculated as (10 - (sum % 10)) % 10 and must match the 18th digit for the CLABE to be valid:

def validate_clabe(clabe):
    """Validate CLABE number using check digit algorithm"""
    
    if len(clabe) != 18 or not clabe.isdigit():
        return False
    
    # Weights for positions 1-17
    weights = [3, 7, 1, 3, 7, 1, 3, 7, 1, 3, 7, 1, 3, 7, 1, 3, 7]
    
    # Calculate weighted sum
    weighted_sum = sum(int(clabe[i]) * weights[i] for i in range(17))
    
    # Calculate check digit
    remainder = weighted_sum % 10
    calculated_check_digit = (10 - remainder) % 10
    
    # Compare with actual check digit
    actual_check_digit = int(clabe[17])
    
    return calculated_check_digit == actual_check_digit

# Example usage
clabe = "012345678901234567"
is_valid = validate_clabe(clabe)
print(f"CLABE {clabe} is {'valid' if is_valid else 'invalid'}")

RFC (Tax ID) Validation

RFC (Registro Federal de Contribuyentes) is Mexico’s tax identification system used alongside CLABE numbers. RFC identifiers come in two distinct formats depending on whether they’re for individuals or businesses:

Type	Length	Structure	Pattern	Example
Individual	13	4 letters + 6 digits + 3 alphanumeric characters	`^[A-Z&Ñ]{4}\\d{6}[A-Z\\d]{3}$`	`MAGR850920XY1`
Business	12	3 letters + 6 digits + 3 alphanumeric characters	`^[A-Z&Ñ]{3}\\d{6}[A-Z\\d]{3}$`	`ABC850920123`

Each RFC format contains specific components that encode different types of information:

Type	Letters Part	Digits Part	Verification Part	Description
Individual	MAGR	850920	XY1	Name-derived letters + birth date + verification code
Business	ABC	850920	123	Business name-derived letters + registration date + verification code

The following functions provide RFC validation and type detection capabilities:

RFC Validation

This function validates RFC format using regex patterns to ensure proper structure for both individual and business formats:

import re

def validate_rfc(rfc):
    """Validate Mexican RFC format"""
    
    if not rfc or len(rfc) < 12 or len(rfc) > 13:
        return False
    
    # Remove spaces and convert to uppercase
    rfc = rfc.replace(' ', '').upper()
    
    # Patterns for validation
    individual_pattern = r'^[A-Z&Ñ]{4}\d{6}[A-Z\d]{3}$'
    business_pattern = r'^[A-Z&Ñ]{3}\d{6}[A-Z\d]{3}$'
    
    # Check if it matches either pattern
    if len(rfc) == 13:
        return re.match(individual_pattern, rfc) is not None
    elif len(rfc) == 12:
        return re.match(business_pattern, rfc) is not None
    
    return False

# Examples
individual_rfc = "MAGR850920XY1"
business_rfc = "ABC850920123"

print(f"Individual RFC {individual_rfc}: {'Valid' if validate_rfc(individual_rfc) else 'Invalid'}")
print(f"Business RFC {business_rfc}: {'Valid' if validate_rfc(business_rfc) else 'Invalid'}")

RFC Type Detection

This function determines whether an RFC belongs to an individual or business based on its length:

def get_rfc_type(rfc):
    """Determine if RFC is for individual or business"""
    
    if not validate_rfc(rfc):
        return None
    
    rfc = rfc.replace(' ', '').upper()
    
    if len(rfc) == 13:
        return 'individual'
    elif len(rfc) == 12:
        return 'business'
    else:
        return None

# Example usage
rfc = "MAGR850920XY1"
rfc_type = get_rfc_type(rfc)
print(f"RFC {rfc} is for: {rfc_type}")

Common Validation Patterns

Common validation patterns involve checking the combined length of CLABE and RFC, ensuring they match the expected formats, and validating the check digits for each component. The following functions provide comprehensive validation for Mexican banking data:

Complete Banking Data Validation

def validate_mexican_banking_data(data):
    """Validate all Mexican banking data fields"""
    
    errors = []
    
    # Validate CLABE
    clabe = data.get('clabe', '').replace(' ', '')
    if not validate_clabe(clabe):
        errors.append("Invalid CLABE format")
    
    # Validate RFC
    rfc = data.get('rfc', '')
    if not validate_rfc(rfc):
        errors.append("Invalid RFC format")
    
    # Validate institution code
    institution = data.get('institution', '')
    valid_institutions = ['40012', '40014', '40021', '40072', '40646', '40137', '40058']
    if institution not in valid_institutions:
        errors.append("Invalid institution code")
    
    # Cross-validate CLABE and institution
    if clabe and institution:
        clabe_bank_code = clabe[:3]
        institution_suffix = institution[2:] if len(institution) == 5 else institution
        if clabe_bank_code != institution_suffix:
            errors.append("CLABE bank code doesn't match institution code")
    
    return {
        'valid': len(errors) == 0,
        'errors': errors
    }

# Example usage
banking_data = {
    'clabe': '012345678901234567',
    'rfc': 'MAGR850920XY1',
    'institution': '40012'
}

validation_result = validate_mexican_banking_data(banking_data)
if validation_result['valid']:
    print("All banking data is valid")
else:
    print("Validation errors:", validation_result['errors'])

CLABE Formatting for Display

def format_clabe_for_display(clabe):
    """Format CLABE for user-friendly display"""
    
    if len(clabe) != 18:
        return clabe
    
    # Format as: 012 345 67890123456 7
    return f"{clabe[:3]} {clabe[3:6]} {clabe[6:17]} {clabe[17]}"

# Example
clabe = "012345678901234567"
formatted = format_clabe_for_display(clabe)
print(f"Formatted CLABE: {formatted}")

Account Masking for Security

def mask_account_number(clabe):
    """Mask CLABE for security display"""
    
    if len(clabe) != 18:
        return clabe
    
    # Show first 3 and last 4 digits
    return f"{clabe[:3]}***********{clabe[-4:]}"

# Example
clabe = "012345678901234567"
masked = mask_account_number(clabe)
print(f"Masked CLABE: {masked}")

Error Messages

When validation fails, your application should handle these standardized error codes to provide clear feedback to users. Each error code corresponds to a specific validation failure with localized message support:

Error Code	English Message
`invalid_clabe`	CLABE must be exactly 18 digits with valid checksum
`invalid_clabe_checksum`	CLABE checksum is invalid
`invalid_rfc`	RFC format is invalid (must be 12-13 alphanumeric characters)
`invalid_institution`	Institution code not found in Mexican banking system
`clabe_institution_mismatch`	CLABE bank code does not match institution code
`invalid_account_type`	Account type must be valid for SPEI transfers

The following code provides a centralized error handling system with support for both English and Spanish messages. Use the get_error_message() function to retrieve localized error messages based on error codes returned by validation functions:

MEXICAN_BANKING_ERRORS = {
    'invalid_clabe': 'CLABE must be exactly 18 digits with valid checksum',
    'invalid_clabe_checksum': 'CLABE checksum is invalid',
    'invalid_rfc': 'RFC format is invalid (must be 12-13 alphanumeric characters)',
    'invalid_institution': 'Institution code not found in Mexican banking system',
    'clabe_institution_mismatch': 'CLABE bank code does not match institution code',
    'invalid_account_type': 'Account type must be valid for SPEI transfers'
}

def get_error_message(error_code, lang='en'):
    """Get localized error message"""
    
    spanish_messages = {
        'invalid_clabe': 'CLABE debe tener exactamente 18 dígitos con suma de verificación válida',
        'invalid_rfc': 'Formato de RFC inválido (debe tener 12-13 caracteres alfanuméricos)'
    }
    
    if lang == 'es' and error_code in spanish_messages:
        return spanish_messages[error_code]
    
    return MEXICAN_BANKING_ERRORS.get(error_code, 'Unknown banking validation error')

Introduction

Direct Integration Guides

Webhooks

Reference Pages

Payment Methods

Resources

CLABE Validation

CLABE Validation Algorithm

RFC (Tax ID) Validation

Common Validation Patterns

Error Messages

See also

Introduction

Direct Integration Guides

Webhooks

Reference Pages

Payment Methods

Resources

​CLABE Validation Algorithm

​RFC (Tax ID) Validation

​Common Validation Patterns

​Error Messages

​See also

CLABE Validation Algorithm

RFC (Tax ID) Validation

Common Validation Patterns

Error Messages

See also