Belgian VAT Number Validation

Belgian VAT numbers (BTW-nummer / Numéro de TVA) consist of 10 digits and use a simple MOD 97 checksum algorithm for validation. In practice, legacy user input may omit the leading zero, so validators often normalize 9-digit input to 10 digits first.

Format Overview

Regex Pattern

^BE[0-9]{9,10}$

Or without country prefix:

^[0-9]{9,10}$

Checksum Algorithm

Belgian VAT numbers use MOD 97 validation:

def validate_be_vat(number):
    # Remove BE prefix if present
    if number.startswith('BE'):
        number = number[2:]

    if len(number) not in (9, 10) or not number.isdigit():
        return False

    # Legacy shorthand may omit the leading zero.
    if len(number) == 9:
        number = "0" + number

    if number[0] not in ('0', '1'):
        return False

    # MOD 97 check
    base = int(number[:8])
    check = int(number[8:])

    return (base + check) % 97 == 0

The last 2 digits are the check digits, calculated as 97 - (first_8_digits % 97).

Important Notes

• Canonical Belgian VAT numbers are 10 digits (0 or 1 first digit)
• Legacy shorthand input with 9 digits can be normalized by adding a leading zero
• Official publications often display grouped notation (0xxx.xxx.xxx / 1xxx.xxx.xxx). This grouping and the dot separators are optional and for readability.
• Numbers starting with 0 are the original series
• Numbers starting with 1 were introduced from September 2023
• Example enterprise numbers published by Belgian authorities include: 0314.595.348, 0553.523.471, 0727.720.427, 1006.872.569