Identifiers — PPSN, Tax Reference Number, VAT number and CRO

In Ireland several identifiers coexist and are easily confused. The PPSN identifies individuals, the VAT number taxable persons, and the CRO number companies on the registry. For e-invoicing and EDI, the crucial distinction is between tax identity (managed by Revenue) and registry identity (managed by the CRO): the former drives Peppol routing (scheme 9935), the latter names the legal entity (scheme 0211).

History — from RSI to PPSN, registry to CRO

The PPSN succeeded the old "RSI Number" (Revenue and Social Insurance) in 1998. It is the Irish citizen's pivotal identifier for access to public services, social benefits and personal taxation. It is issued by the Department of Social Protection (DSP) via Client Identity Services.

In parallel, the Companies Registration Office (CRO) has maintained the register of Irish companies since the 19th century. Every incorporated company receives a sequential CRO number, independent of its tax identity. This separation between the companies registry and the tax administration is standard in common-law countries.

Irish identifiers — formats
===========================

PPSN  (Personal Public Service Number)
  Format : 7 digits + 1 or 2 letters    e.g. 1234567T  / 1234567TA
  Issued by : DSP (Dept. of Social Protection) via Client Identity Services
  Use : individuals (employment, benefits, personal tax)

Tax Reference Number (TRN)
  Individual : = PPSN
  Company : Revenue tax number (often ALIGNED with the VAT number)

Irish VAT number
  Old format : IE + 7 digits + 1 letter     e.g. IE1234567T
  New format : IE + 7 digits + 2 letters    e.g. IE1234567WI
  Country prefix : IE (intra-EU, VIES)
  Peppol scheme : 9935

CRO number (Companies Registration Office)
  Format : sequential number (1 to 7 digits)    e.g. 634215
  Issued by : CRO (companies registry)
  Peppol scheme : 0211
  Use : LEGAL identity of the entity (not routing)

Governance — Revenue, DSP, CRO

• Revenue Commissioners — assign the Tax Reference Number and VAT number, manage VAT registration and VIES.
• Department of Social Protection (DSP) — issues and manages the PPSN.
• Companies Registration Office (CRO) — incorporates companies and assigns the CRO number; also runs the register of beneficial owners (RBO).

These three authorities are distinct but interconnected: a company incorporates at the CRO, then registers for VAT with Revenue. A company's VAT number and Tax Reference Number are often aligned, which adds to the confusion.

Schema — formats and Peppol codes

On Peppol, routing an Irish e-invoice rests on the VAT number via scheme 9935. The legal entity (company name, CRO number) appears in PartyLegalEntity with scheme 0211:

Tax identity vs registry identity

Usage in e-invoicing and EDI

• Peppol routing. The Irish EndpointID most often uses the VAT number (9935). It is what lets the SMP locate the recipient.
• VIES validation. The IE prefix + VAT number can be checked in the EU VIES system — a key step for exempt intra-EU supplies (category K).
• GLN in retail. On the EDIFACT/EANCOM side, delivery points are identified via GS1 GLNs, distinct from tax identifiers — see the retail EDIFACT page.
• CRO number in BT-30. In an EN 16931 invoice, the CRO number populates the seller's legal registration identifier (BT-30), complementing the VAT number (BT-31).

Common pitfalls

• Putting the CRO number in the EndpointID. Peppol routing uses the VAT number (9935), not the CRO (0211). Swapping them breaks delivery.
• Confusing the two VAT formats. The old format (1 letter, e.g. IE1234567T) and the new one (2 letters, e.g. IE1234567WI) coexist. An over-strict regex validation wrongly rejects valid numbers.
• Using the PPSN as a company identifier. A confidentiality and logic error: a company is identified by VAT + CRO, never by PPSN.
• Assuming TRN ≠ VAT number. For many companies they are aligned; but it is not a universal rule — check with Revenue.
• Dropping the check letter. The letter(s) at the end of the VAT number are check characters; omitting them makes the number invalid for VIES.

Cross-links

• Ireland hub — full view
• OGP — Peppol Authority B2G 2019
• VAT regimes — 23 / 13.5 / 9 / 0%
• ROS — Revenue Online Service
• Retail EDIFACT — Dunnes, Musgrave, Tesco
• CRO — Companies Registration Office
• Revenue — VAT registration