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. The BE number format has changed several times over the years, which means input can arrive in a few different shapes. This guide walks through the format, the changes, and how to normalize and validate each variant.

Format Overview

Regex Pattern

Allows optional dot grouping (0xxx.xxx.xxx / 1xxx.xxx.xxx / xxx.xxx.xxx):

^BE[0-9]{3,4}(\.?[0-9]{3}){2}$

Or without country prefix:

^[0-9]{3,4}(\.?[0-9]{3}){2}$

Strict (digits only, no dots):

^BE[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:]

    # Strip dot grouping (e.g. "0314.595.348" -> "0314595348")
    number = number.replace('.', '')

    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).

9 digit vs 10 digit format

• Canonical Belgian VAT numbers are 10 digits (0 or 1 first digit).
• Numbers starting with 0 are the original series.
• Numbers starting with 1 were introduced on 19 September 2023, when the 1-range (reserved in the 2003 format spec) was activated as the 0-range neared exhaustion.
• Legacy shorthand input with 9 digits can be normalized by adding a leading zero. For example, BE111222333 (9 digits) becomes BE0111222333 (leading 0 + original 9 digits).
• Always normalize 9-digit input to the 10-digit form before running the checksum or sending to VatDB.

Important Notes

• Official publications often display grouped notation (0xxx.xxx.xxx / 1xxx.xxx.xxx). This grouping and the dot separators are optional and for readability.
• Example enterprise numbers published by Belgian authorities include: 0314.595.348, 0553.523.471, 0727.720.427, 1006.872.569