Free offline checkers for the Spanish DNI/NIE, Portuguese NIF, Italian codice fiscale, German Steuer-ID, French social security number (NIR) and Dutch BSN. Each one runs the official check-digit rule, so you can catch a typo before a form or a bank rejects it.
Only checks typing.It does not prove the number exists or belongs to anyone. A number can pass and still be unissued, and a real number can be typed wrongly in a way that still passes.
Private by design: the check runs in your browser. Nothing you type is sent anywhere or stored, and it works offline. Do not type other people's numbers.
The summaries of official texts are in English; labels, country names and notes follow your language.
ES
Spain · DNI / NIE
Spaces, dots and dashes are ignored.
Synthetic example (fake, computed to pass)
Format
DNI: 8 digits and 1 letter. NIE: X, Y or Z, 7 digits and 1 letter. Example shape: 12345678Z or X1234567L.
How the check works
Take the number (for an NIE replace X, Y, Z with 0, 1, 2), divide by 23 and look up the remainder in the table TRWAGMYFPDXBNJZSQVHLCKE (remainder 0 = T, 1 = R, and so on). That letter must be the last character.
9 digits; the last one is the check digit. Decreto-Lei 14/2013: the first eight are sequential, the last is a control digit.
How the check works
Multiply the first 8 digits by 9, 8, 7, 6, 5, 4, 3, 2 and add them up. Take the sum modulo 11. If the remainder is 0 or 1 the check digit is 0, otherwise it is 11 minus the remainder.
UNVERIFIED: algorithm widely used; not officially documented. We found no official Autoridade Tributária page that publishes the formula. The law only says the last digit is a control digit.
16 characters: 6 letters (surname and name), 2 digits (year), 1 letter (month), 2 digits (day, +40 for women), 1 letter and 3 digits (place), 1 control letter. In case of duplicates some digits are replaced by the letters LMNPQRSTUV.
How the check works
Convert the first 15 characters to numbers with two tables (one for odd positions 1, 3, 5..., one for even positions), add them up, take the sum modulo 26 and turn the remainder into a letter (0 = A ... 25 = Z). That letter must be the 16th character.
Partly verified: the Agenzia delle Entrate says the check character follows D.M. 23 December 1976, but the page we read does not print the two conversion tables. The tables here reproduce a widely published worked example (RSSCLD50R15H501Y), which is not an official Agenzia page.
11 digits, no leading 0 (only test numbers have one). The 11th digit is the check digit. In the first 10 digits exactly one digit appears two or three times, and never three times in a row.
How the check works
ISO 7064 MOD 11,10 over the first 10 digits: start with a product of 10; for each digit add it to the product, take modulo 10 (a 0 counts as 10), double it and take modulo 11. The check digit is 11 minus the final product (10 becomes 0).
15 characters: 1 digit (sex), 2 (birth year), 2 (month), 2 characters (département; Corsica is 2A or 2B), 3 (commune), 3 (order number), then the 2-digit key.
How the check works
Key = 97 minus the remainder of the first 13 digits divided by 97. For Corsica, write 2A or 2B as 00, then subtract 1 000 000 (2A) or 2 000 000 (2B) from the 13-digit number before dividing.