NIP Poland Validator

What is the Polish NIP?

The NIP (Numer Identyfikacji Podatkowej) is Poland's tax identification number, used mainly by businesses and sole traders to deal with the tax authorities and to issue VAT invoices. It is a 10-digit number.

The NIP is sometimes written with separators such as XXX-XXX-XX-XX or XXX-XX-XX-XXX, but the digits themselves are what matter. For EU VAT purposes it is prefixed with PL.

Check-digit algorithm

The 10th digit is a check digit computed from the first 9:

• Apply the weights [6, 5, 7, 2, 3, 4, 5, 6, 7] to the first 9 digits.
• Multiply each digit by its weight and sum the products.
• Take the sum modulo 11 — the result is the expected check digit.
• If the remainder equals 10, the number is invalid (such a NIP is never issued).

NIP vs REGON vs PESEL

Poland has three identifiers that are easy to mix up:

• NIP — 10 digits, tax ID, mostly for businesses.
• REGON — statistical register number, 9 or 14 digits.
• PESEL — 11-digit personal ID for individuals (encodes date of birth and sex).

Common pitfalls

• Leaving the dashes in XXX-XXX-XX-XX — strip everything but digits before validating.
• Including the PL VAT prefix in the 10-digit count.
• Accepting a number whose modulo-11 remainder is 10 — that case is invalid, not "rounded".
• Confusing the 10-digit NIP with the 9- or 14-digit REGON.

FAQ

Can individuals have a NIP? Yes — sole traders and some taxpayers use a NIP, but most private individuals are identified by their PESEL instead.

What if the check digit would be 10? The number is simply invalid; the authorities never assign a NIP that would require a two-digit check value.

Does a valid NIP mean the company is active? No. The checksum only confirms the format; check the official VAT/white-list registers for current status.