How long is a Partita IVA?

Exactly 11 digits. The first seven generally identify the taxpayer, the next three identify the issuing provincial office, and the eleventh is the check digit computed from the first ten.

How is the check digit calculated?

Add the digits in odd positions directly. Double the digits in even positions and subtract 9 if the result exceeds 9. The check digit is (10 minus the units of that total) modulo 10, and it must equal the 11th digit.

Is this the same as the Luhn algorithm?

It is a Luhn-variant. The doubling and digit-folding of even-position digits is identical to Luhn, but Italian numbering positions and the final modulo step make it the Agenzia delle Entrate variant rather than plain Luhn.

Does a valid check digit mean the VAT number is active?

No. A valid check digit only proves the number is internally consistent. To confirm the business is currently VAT-registered for intra-EU trade, query the EU VIES service.

Is my number sent anywhere?

No. The entire checksum runs in your browser, so the Partita IVA never leaves your device.

Italy Partita IVA Validator

A Partita IVA is the 11-digit VAT number assigned to businesses and self-employed professionals in Italy. It appears on every invoice and is required for reverse-charge and intra-EU transactions. Before relying on one, you can confirm it is well-formed with the official check-digit algorithm — useful for accountants, e-invoicing developers, and anyone validating Italian suppliers.

How it works

The Agenzia delle Entrate uses a Luhn-variant modulo-10 check on the first ten digits to derive the eleventh:

Strip everything but the 11 digits.
Add the digits in odd positions (1st, 3rd, 5th, 7th, 9th) directly.
For digits in even positions (2nd, 4th, 6th, 8th, 10th), double each one and subtract 9 if the result is greater than 9.
Sum both parts to get the weighted total.
The check digit is (10 - (total mod 10)) mod 10, and it must equal the 11th digit.

Example

For 00743110157, the weighted total of the first ten digits is 23. The units digit is 3, so the check digit is (10 - 3) mod 10 = 7, which matches the final digit — the number is valid.

Notes

A valid check digit confirms the number is internally consistent, not that the business is currently registered or active. For real-time confirmation in intra-EU dealings, query the EU VIES system. This tool performs no lookup and runs entirely in your browser.