How to Use the Ireland PPS Number Validator
- Type or paste a PPS number into the box above (7 digits + 1–2 letters).
- Click Check. The tool verifies the 7 digits and recomputes the official mod-23 check letter.
- Read the decode table showing the digits, check letter, and any optional trailing letter split out.
- Nothing you type is uploaded anywhere — the whole calculation runs as plain JavaScript in your browser tab.
What a PPS Number Is
Ireland's Personal Public Service (PPS) Number is a unique identifier used across social welfare, tax (Revenue), health services, and employment. It consists of 7 digits followed by 1 or 2 letters: the first letter (positions A–W) is a check letter computed from the 7 digits, and an optional second letter — commonly A, B, H, or W — indicates how or when the number was allocated (for example, distinguishing an individual from a non-personal/company registration under the modern allocation scheme).
The Checksum: Mod-23 Check Letter
The check letter uses a weighted-sum algorithm: each of the 7 digits is multiplied by a descending weight (8, 7, 6, 5, 4, 3, 2, left to right), the products are summed, and the sum modulo 23 selects a letter (a remainder of 1 maps to A, 2 to B, and so on up to 22 mapping to V; a remainder of exactly 0 maps to W). This is the same family of weighted-checksum algorithm historically used for Irish VAT numbers, since PPS numbers and VAT numbers share Ireland's Revenue-administered numbering heritage.
Worked Example
6433435FWhy This Tool Is Scoped Conservatively
We label this validator lower-confidence deliberately: published sources describe two different PPS check algorithms depending on the number's era — a straightforward 7-digit-plus-check-letter formula (the one implemented here, verified against a documented test case) for the traditional format, and a more elaborate calculation incorporating the optional second letter for some numbers issued under the modern allocation scheme. Rather than guess at the second formula and risk wrongly rejecting a real, valid PPS number, this tool checks only the well-documented primary check letter and treats any second letter as informational — shown in the decode table, but not used in the checksum. If you have a PPS number with a second letter that this tool doesn't fully explain, treat that as a limitation of this tool, not evidence the number itself is wrong.
What This Tool Does NOT Do
This checks the 7-digit-plus-check-letter structure only. It does not query the Department of Social Protection (MyWelfare) or Revenue's systems, and cannot confirm a PPS number is actually issued or belongs to a real person. For anything that matters — employment, welfare claims, tax registration — use the official channels.
Common Mistakes
- Assuming the optional second letter is part of the mod-23 checksum — it isn't, in this tool's scope
- Confusing a PPS number with an Irish tax reference number, which follows different conventions in some contexts
- Mistyping a digit in the middle of the 7-digit block — the mod-23 check letter is specifically designed to catch this
- Treating a passing checksum as proof the number is currently active — this tool has no way to know that
Frequently Asked Questions
Is my PPS number uploaded anywhere? No — everything runs locally in your browser tab.
Does this tool check the optional second letter? No — by design, to avoid guessing at an algorithm we can't confidently verify. See the scope note above.
Does a valid checksum mean the PPS number is real? No — it means the number is internally consistent, not that it's actually issued.
Is this tool free? Yes, completely free, with no login and no usage limit.