My number is real but this says it is not valid. Why?

Check for a transposed pair of digits first — that is the single most common cause, and every checksum here is designed to catch it. Failing that, the number may predate the current rule: several countries changed or introduced their checksum at a known date, and older numbers were not reissued. If the tool names a specific rule that failed, that is the one to look at.

Does a valid result mean the number is registered?

No, and this is the limit worth understanding. A checksum proves the digits are mutually consistent, which catches typos and made-up numbers. It cannot prove the number was issued, is still active, or belongs to the person quoting it. Only the issuing authority's own lookup can do that.

CNP Validator – Check a Romanian identity number online

Cod Numeric Personal

Romania · Individuals

0000000000000

Enter a number to check

Paste or type the number — punctuation is optional.

Other identifiers

Cross-border

IBAN LEI EU VAT

Americas

CPF CNPJ CUIT / CUIL RUT / RUN NIT RUC CURP SIN / NAS SSN EIN

Oceania

ABN ACN TFN IRD number

Africa

SA ID KRA PIN الرقم القومي NIN

What this check does — and what it cannot do

This tool checks the number's structure and its check digit, using the published algorithm for that document. A number that passes is well formed: it is arithmetically consistent and could have been issued.

It cannot tell you whether the number was actually issued, whether it is active, or who it belongs to. Only the issuing tax authority can confirm that, through its own lookup service. Treat a passing result as "worth submitting", never as proof of identity.

How the CNP check works, and what the number tells you

A CNP is a personal identity number issued in Romania. This page checks one against the published rule, shows which specific test it fails when it fails, and decodes the facts the digits carry. Everything runs in your browser — the number you type is never sent anywhere.

How it works

Applies the published checksum rather than only checking the length and shape.
Names the exact rule that failed, so a typo is distinguishable from a number that was never valid.
Decodes what the number encodes: date of birth, sex, county code.
Does not generate numbers. This one identifies a person, and a page that manufactures plausible identity numbers is a liability rather than a feature.

13 digits: S YY MM DD JJ NNN C
  S   century and sex
        1 2  1900s male / female
        3 4  1800s
        5 6  2000s
        7 8  resident foreigners
  JJ  county code

  weights 2 7 9 1 4 6 3 5 8 2 7 9
  c = sum mod 11, written as 1 when that is 10

Worked example

Checking 1800101221144, a valid CNP, digit by digit.

input 1800101221144
Date of birth 1980-01-01
Sex Male
County code 22
Checksum Weighted mod 11
result passes every published check

The checksum passes, so the number is internally consistent, and the tool reads off date of birth, sex, county code. Internal consistency is not the same as the number being issued to somebody — see the note below.

Reading the result

A passing checksum means the digits are consistent with each other, not that the number exists. Only Romania's own registry can tell you whether a number was actually issued and is still valid, and no offline tool can substitute for that.
The check happens entirely in your browser. Nothing is uploaded, logged, or stored, which matters more here than on most tools because these numbers are personal data in every jurisdiction that issues them.
Punctuation is ignored. Spaces, dots, dashes and slashes are stripped before the check, so a number pasted in any common local format is read the same way.

Common questions

My number is real but this says it is not valid. Why?: Check for a transposed pair of digits first — that is the single most common cause, and every checksum here is designed to catch it. Failing that, the number may predate the current rule: several countries changed or introduced their checksum at a known date, and older numbers were not reissued. If the tool names a specific rule that failed, that is the one to look at.
Does a valid result mean the number is registered?: No, and this is the limit worth understanding. A checksum proves the digits are mutually consistent, which catches typos and made-up numbers. It cannot prove the number was issued, is still active, or belongs to the person quoting it. Only the issuing authority's own lookup can do that.