How is the NIF check digit calculated?

The first eight digits are weighted by 9, 8, 7, 6, 5, 4, 3 and 2, summed, and reduced modulo 11. The control digit is 11 minus that remainder; if the result is 10 or 11 it becomes 0. The 9th digit must equal this control digit.

Does a valid result mean the NIF really exists?

No. The tool only confirms the format and modulo-11 check digit are correct. A structurally valid NIF is not necessarily one that has actually been assigned, and it is never checked against any tax register.

Is my NIF sent anywhere?

No. The validator is privacy-first — all processing happens locally in your browser and the number never leaves your device.

Portugal NIF Validator

Validate a Portuguese NIF/NIPC and read its taxpayer type.

Portugal NIF validator

Validate a 9-digit Portuguese NIF (Número de Identificação Fiscal) or NIPC. The tool verifies the modulo-11 check digit and identifies the taxpayer type from the leading digit(s) — individual, company, public entity, sole trader and more.

It is privacy-first: nothing leaves your browser. The validator only checks the structure and check digit — it does not verify the number against any tax register.