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Portugal NIF Check

Local processing · not uploaded

Validate Portuguese tax numbers (NIF) online: 9 digits, the first indicates the taxpayer category and the last is a weighted mod-11 check digit. The tool verifies the digit and reads the category.

Sample (click to fill): 123456789

Number—
Category—
Expected digit—
Validation—

NIF structure and checksum

A Portuguese tax number (NIF / Número de Identificação Fiscal) has 9 digits, the first indicating the taxpayer category:

Algorithm: multiply the first 8 digits by weights 9 8 7 6 5 4 3 2, sum, take mod 11; 11 − remainder is the check digit (0 if it is 10 or 11), compared with the 9th digit.

How to use

1

Paste or type the ID number above (use the sample to try it out)

2

Click “Check”, and the tool verifies structure and check digit locally in your browser

3

See instantly whether it is valid — nothing is uploaded, no real identity is looked up

✅What this tool does

  • Check the number is exactly 9 digits
  • Read the individual/company category from the first digit
  • Verify the last check digit by the weighted mod-11

💡Tips

  • Valid does not mean it exists: only encoding rules and checksum are verified, no personal data is looked up
  • Do not enter other people’s real ID numbers — protect personal privacy
  • Numbers are processed locally in your browser, never uploaded — no signup, no install

🔒 Local processing · numbers not uploaded · only structure and checksum are checked

← Back to Global ID Validator

FAQ

Q1Does a valid result mean it is a real tax number?
No. The tool only checks whether the 9th digit is consistent under the weighted mod-11. It connects to no Portuguese tax system and looks up no real taxpayer data.
Q2Is the number uploaded?
No, everything is computed locally in your browser and the number never leaves your device.
Q3What does the first digit mean?
It marks the taxpayer category: 1/2/3 individuals, 5 companies, 6/8/9 public bodies and sole traders. The tool displays the category accordingly.