VAT Number Check Guide Reviewed 10 October 2026

VAT Number Check Ireland: VIES Validation Guide

How to check an Irish or EU VAT number through VIES, understand the result and keep evidence for cross-border VAT records.

Quick answer

  • Use the European Commission VIES service to validate an EU VAT number for intra-EU trade.
  • Select the customer country and enter the number without guessing or changing its characters.
  • A valid VIES result supports the VAT-number check but does not prove every other condition for zero-rating or reverse charge.
  • Save the date, result and reference or screenshot with the transaction records.
On this page
  1. Check the number on official VIES, then act on the result
  2. What does VIES check?
  3. How to validate a VAT number step by step
  4. Irish VAT number, tax number and CRO number
  5. Why a VAT-number check may fail
  6. Keep an evidence record that another person can follow

Check the number on official VIES, then act on the result

Open official VIES VAT-number validation →

Use the customer’s supplied number, issuing country and legal details. This guide does not run a live validation or provide a number to copy.

Response Next action
Valid Match the customer identity and keep the result. Check the other conditions for the transaction’s VAT treatment.
Invalid Recheck country and transcription. Ask the customer to resolve registration or intra-EU activation with its tax authority.
Service error or data unavailable Record the error and retry later. This is an incomplete check, not proof that the number is invalid.

If identity information is missing or inconsistent, seek confirmation from the relevant national tax authority. Follow the European Commission’s response guidance. An unavailable service does not justify choosing a number that happens to validate.

What does VIES check?

VIES checks whether a VAT number is recorded as valid for intra-EU transactions. It is the appropriate public check when an Irish business needs to validate an EU customer’s VAT status before applying cross-border VAT treatment.

Important limit: a valid number is only one part of the evidence. The supplier may also need to verify the customer’s identity, the transaction, where goods moved or where services were supplied, and the invoice wording.

How to validate a VAT number step by step

  1. Ask the customer for its legal name, address, country and VAT number.
  2. Open the official VIES VAT-number validation service.
  3. Select the Member State that issued the number.
  4. Enter the VAT number carefully, normally without adding the country prefix twice.
  5. If available, enter your own VAT number so the enquiry can be linked to the supplier.
  6. Review whether the result is valid and whether returned identity details match the customer.
  7. Save the result, date and reference with the invoice and transport or service evidence.

Irish businesses approved for intra-EU VAT registration are automatically registered for VIES. A domestic-only VAT registration may therefore need to be updated before intra-EU trading begins.

Irish VAT number, tax number and CRO number

An Irish VAT number is a tax identifier and normally begins with the country code IE when used for EU trade. It is not the same thing as a CRO company number. Formatting can vary because older and newer Irish identifiers do not all look identical, so use the official validation result instead of relying only on visual format.

Identifier What it identifies Best check
VAT number VAT registration and, where applicable, intra-EU VAT status VIES for EU validation; Revenue records for your own registration
CRO number A company or registered business record Companies Registration Office
Tax reference number A taxpayer or tax registration Revenue correspondence or ROS

Why a VAT-number check may fail

  • The country or number was entered incorrectly.
  • The registration is domestic-only and not active for intra-EU trade.
  • The registration is new and has not yet appeared in the relevant system.
  • The VAT number was cancelled or is not valid for the transaction date.
  • The VIES service or a national database is temporarily unavailable.

Recheck the number and country, ask the customer to confirm its legal details and registration status, and retain the failed result. Do not change a number until it produces a valid response or assume that a company name alone proves VAT registration.

Keep an evidence record that another person can follow

A useful internal record separates what the service returned from what your business decided. For an illustrative enquiry, use this structure rather than a fabricated VAT number:

Field Record
Customer and transaction Legal name, address, order or invoice reference, and supply date.
Input checked Issuing country and the exact customer-supplied VAT number.
Check details Date, time and time zone, source, operator and request reference if supplied.
Returned result Valid, invalid or an error; retain the original response or capture.
Follow-up Customer correspondence, national-authority confirmation or the later retry result.
Tax decision Who approved the VAT treatment and which other transaction evidence supports it.

For example, a failed service enquiry followed by a valid response needs two entries. Keep the failed attempt and the successful retry with their actual timestamps; do not overwrite the first entry or backdate the second. A later check is not a historical certificate for every earlier supply.

Revenue explains VAT record retention and domestic-only versus intra-EU registration. Use the VAT Calculator afterwards for invoice arithmetic. It cannot validate a registration or decide place of supply; the reverse-charge guide covers the separate treatment question.

Frequently asked questions

How do I check an Irish VAT number?

Use the official VIES service for intra-EU validation, select Ireland and enter the number carefully. Save the result with the transaction records.

What does a valid VIES result prove?

It confirms that the number is recorded as valid for intra-EU VAT purposes at the time of the check. It does not prove all other conditions for zero-rating or reverse charge.

Why is a VAT number invalid on VIES?

An invalid response may reflect an incorrect number, domestic-only status, unfinished registration or cancellation. Recheck the details and ask the customer to confirm intra-EU status. A service error is a separate incomplete check; retry later.

Is an Irish VAT number the same as a company number?

No. The VAT number is a tax identifier, while the CRO number identifies a company or registered business record.

Should I keep evidence of a VAT-number check?

Yes. Keep the date, result and any enquiry reference or screenshot with the invoice and other evidence supporting the transaction.

Sources & references

Back to VAT Ireland
Reverse Charge VAT Ireland 2026: Rules & Examples Irish reverse-charge VAT explained for services received from abroad, intra-EU trade, construction, invoices and VAT3 self-accounting. VAT Invoice Requirements Ireland: Quotes, Receipts & Invoices Irish VAT invoice requirements, issue dates, full and simplified invoices, quote-to-invoice examples, corrections and reverse-charge wording. VAT Registration Ireland 2026: Thresholds & How to Register Irish VAT registration thresholds for services, goods and cross-border activity, plus voluntary registration, sole traders and the ROS application process.

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