Finnish VAT Number Validation
Format, pattern, and MOD 11-2 checksum algorithm for FI VAT numbers
Finnish VAT numbers (Arvonlisäveronumero or ALV-numero) consist of 8 digits and use a MOD 11-2 weighted checksum algorithm.
Format vs. Active Validation
This checks format only, not if a VAT number is really registered. Use VatDB's API to verify is a number is really registered and active. VatDB checks official EU and national datasources.
Format Overview
| Property | Value |
|---|---|
| Country Code | FI |
| Format | 8 digits |
| Length | 8 digits |
| Examples | FI01120389 FI19274001 FI23365096 |
Regex Pattern
^FI[0-9]{8}$
Checksum Algorithm (MOD 11-2)
def validate_fi_vat(number):
if number.startswith('FI'):
number = number[2:]
if len(number) != 8 or not number.isdigit():
return False
weights = [7, 9, 10, 5, 8, 4, 2]
total = sum(int(d) * w for d, w in zip(number[:7], weights))
check = 11 - (total % 11)
if check == 11:
check = 0
elif check == 10:
return False # Invalid number
return check == int(number[7])
Note: If the check calculation results in 10, the VAT number is invalid.
Frequently Asked Questions
How do I verify a Finnish VAT number (ALV-numero)?
Finnish VAT numbers use MOD 11-2 with weights [7,9,10,5,8,4,2]. If the check equals 10, the number is invalid. If 11, check digit is 0. Use VatDB's API for official verification against EU and national databases.
What does a Finnish VAT number look like?
A Finnish VAT number has the format FI12345678 - 'FI' followed by exactly 8 digits. The last digit is a check digit calculated using MOD 11-2.
How many digits are in a Finnish VAT number?
A Finnish VAT number contains exactly 8 digits after the FI country code. The complete number is 10 characters: FI + 8 digits.
What is a Finnish ALV-numero?
ALV-numero (Arvonlisäveronumero) is the Finnish VAT number. ALV stands for 'Arvonlisävero' which means Value Added Tax in Finnish.
Where can I check a Finnish company's VAT number?
Verify VAT numbers using VatDB's API, which checks official EU and national databases in real-time. Returns company details with each validation.
What's the difference between format validation and checking if a VAT number is active?
Checksum validation catches typos but can't detect fake numbers. A mathematically valid number might never have been issued. VatDB's API confirms genuine, current registration.
Can you show some real Finnish VAT number examples?
Here are three real, currently active Finnish VAT numbers you can test: FI01120389, FI19274001, FI23365096.