Tax Identification Number (NIF) Validator

Quickly and easily validate your NIF (Tax Identification Number)! Our NIF validator ensures the authenticity of the provided number, confirming that it is valid and error-free. If you need to generate a new NIF, try our NIF generator.

This tool generates fictitious data intended exclusively for software testing and development purposes. The data does not correspond to real people or entities and must not be used for illegal, fraudulent purposes, or in ways that violate the privacy of others. Compliant with LGPD (Brazilian Data Protection Law).

See also:

Numeral System
Voter ID Validator
CEP Lookup
AIH Generator
SIN Validator (Canada)
Credit Card Validator
API Testing with Fictitious Data
EIN (USA)

How NIF Validation Works

What does the validator check?

The Help4Dev NIF validator checks whether the check digit (last of the 9 digits) of a Portuguese Fiscal Identification Number is mathematically correct by the Portuguese Tax Authority algorithm. Weights 9, 8, 7, 6, 5, 4, 3, and 2 are applied to the first 8 digits, the sum is calculated, and the expected verifier is determined by modulus 11. It also identifies the entity category from the first digit.

When is a NIF considered invalid?

A NIF is invalid when: (1) it does not have exactly 9 digits; (2) it starts with 0 (invalid for any category); (3) the check digit does not match the calculation with weights and modulus 11. Additionally, NIFs with all identical digits are rejected. The validator also reports the identified category (Individual, Corporation, Public Entity, etc.).

Why validate NIF in development?

E-commerce systems for the Portuguese market, electronic invoicing platforms (AT), ERPs with Portuguese fiscal modules, and integrations with Tax Authority services need to validate NIF in forms. The Help4Dev validator allows instant verification of whether a NIF is mathematically correct, facilitating development and testing of applications with the Portuguese market.