Is VIES Down? › MS_UNAVAILABLE

VIES MS_UNAVAILABLE: what it means and what to do

MS_UNAVAILABLE means VIES could not get an answer from the country holding the VAT number. Learn what to record, when to retry, and how to check a number separately.

What it means

Your VAT number check came back with this code instead of a yes or no. Nothing is wrong with your request, and you have not done anything unusual.

This happens, and it is handled by recording the outcome and trying again later. No data is lost. The check was never completed, so there is nothing to undo.

VIES, the EU's VAT number checking service, does not answer checks on its own. It passes each check to the member state, the EU country whose tax office holds the number. When that country's system does not answer, VIES reports MS_UNAVAILABLE. The code says nothing about the number. It does not tell you whether the number is valid or invalid. Keep the outcome as unavailable and retry later.

A problem with one country's service does not mean every country is affected. The country status below shows which services are answering right now. Treat it as context. It is not a verdict on your customer's VAT number.

What your application should record

Keep three outcomes separate:

An invalid result and a failed request are different things. Do not store an outage as valid: false. A successful HTTP response on its own is not a completed VAT check either.

Which member states return MS_UNAVAILABLE most

558 occurrences of MS_UNAVAILABLE observed across all member states in the last 7 days, from our own 5-minute checks. Monitoring began 2026-08-09.

What to do about it

1. Confirm the country prefix and the number you submitted.
2. Check whether that country's national service is currently having problems.
3. Retry later, with a limited number of attempts and a growing delay between them. Avoid rapid retry loops.
4. If checks stay unavailable, keep the item pending and follow your usual verification process. Your counterparty can ask its own national tax administration about registration questions.

Do not change the tax treatment of an invoice automatically because a lookup failed.

Checking a specific VAT number and keeping the result

The VIES Monitor shows whether each country's service is available. To check an individual number, open hosted invoice checks and select Live VAT verification. You will need an API key (the private code that identifies your account to the service), and the number is sent to EU VIES.

Attestwire returns valid, invalid or unavailable, with the time of the check and an evidence receipt, the dated record of what the check returned. A valid or invalid result uses one document from your allowance. An unavailable result is not charged. Download the complete response if you need to keep it. This service does not store the receipt for you.

The receipt describes what was observed at that time. It does not establish historical validity, identity, or the correct tax treatment. Not every receipt is signed, so check evidence.signing_status rather than assuming.

Developers can call POST /v1/vat/verify, or the MCP tool verify_vat_vies (a tool an AI assistant can call). See the request and evidence documentation.

About VIES itself: the European Commission's VAT number checking guidance.

Example: an unavailable result kept pending

This excerpt is for illustration only. It is not a live response or a complete receipt:

{
  "check": "vat",
  "status": "unavailable",
  "reason": "MS_UNAVAILABLE",
  "charged": false
}

Frequently asked questions

Hit a different error?

• MS_MAX_CONCURRENT_REQ — MS_MAX_CONCURRENT_REQ means a member state is already handling as many simultaneous VIES lookups as it will take.
• GLOBAL_MAX_CONCURRENT_REQ — GLOBAL_MAX_CONCURRENT_REQ means the VIES front end — not one member state — is handling as many simultaneous requests as it will take.
• TIMEOUT — A VIES timeout means no answer arrived before your deadline.

← Live VIES status for all 28 VIES endpoints