The Irish VAT number: format and verification

Updated: July 2026

An Irish VAT registration number is the prefix IE followed by 7 digits and one or two letters. IE1234567T is the older single-letter style, and IE1234567FA the format issued since 2013. The number is issued by Revenue when your VAT registration is approved and it follows the business through every invoice, return and reclaim after that.

Where the number must appear

• On every VAT invoice you issue. An invoice without a valid VAT number does not support the customer's input deduction, which is why business customers chase missing numbers so quickly.
• On credit notes, on your VAT3 returns, and in correspondence with Revenue.
• When buying from EU suppliers: quoting a VIES-listed number is what lets them zero-rate the sale to you.

Checking a number on VIES

The European Commission's VIES service checks any EU VAT number free of charge and tells you whether it is currently valid, and for most countries the registered name and address. Two things catch people out. First, only Irish numbers with intra-EU status under two-tier registration appear on VIES; a legitimate domestic-only trader will show as invalid there even though their number works perfectly for Irish invoicing. Second, a VIES check protects you: zero-rate an EU sale against a number you never verified and the VAT liability can bounce back to you if the number turns out bad.

VAT number, tax reference and CRO number

Three identifiers get mixed up constantly. The VAT number is your tax reference number with the IE prefix and, for newer registrations, an extra letter. The plain tax reference covers income tax or corporation tax. The CRO number is a company registration identifier with no tax function at all. Quoting the CRO number on an invoice where a VAT number belongs is one of the most common invoicing errors Revenue sees, and it invalidates the customer's deduction until corrected.