How is the PPSN check letter calculated?

The seven digits are weighted by 8, 7, 6, 5, 4, 3 and 2. If a second letter is present, its A=1..Z=26 value times 9 is added. The total is reduced modulo 23; a remainder of 0 maps to W, otherwise the remainder selects the letter A-V. That letter must equal the 8th character.

Does a valid result mean the PPSN really exists?

No. The tool only confirms the format and modulo-23 check letter are correct. A structurally valid PPSN is not necessarily one that has been assigned, and it is never checked against any government register.

What is the format of a PPS number?

A PPSN is seven digits followed by a check letter, and optionally a second letter (e.g. 1234567T or 1234567TA). The second letter was added in 2013 to extend the range of available numbers.

What does the check letter range cover?

The check letter is A through W. A modulo-23 remainder of 0 maps to W, and remainders 1 to 22 map to letters A through V respectively, giving 23 possible check characters.

Can a PPS number contain spaces?

PPSNs are written without spaces. The validator focuses on the seven digits plus the check letter (and optional second letter); enter them as a continuous string for a correct result.

Is my PPS number sent anywhere?

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

Ireland PPS Number Validator

Ireland PPS number validator

Validate an Irish PPS Number (Personal Public Service Number) used for tax, social welfare and public services. This helps catch data-entry typos in forms and software before a number is submitted, without ever contacting a government system.

How it works

The number is 7 digits + a check letter, with an optional second letter (post-2013). The check letter is computed with a modulo-23 algorithm:

Multiply the seven digits by weights 8, 7, 6, 5, 4, 3, 2 and sum them.
If a second letter is present, add its value (A=1 … Z=26) × 9.
Take the total modulo 23. A remainder of 0 maps to W; remainders 1–22 map to A–V.

That computed letter must equal the 8th character of the PPSN.

Example

For 1234567: (1×8 + 2×7 + 3×6 + 4×5 + 5×4 + 6×3 + 7×2) = 8 + 14 + 18 + 20 + 20 + 18 + 14 = 112. 112 mod 23 = 20, which maps to the letter T. So 1234567T has a valid check letter.

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