Consultation number
A reference identifier returned by VIES that proves you queried a VAT number on a specific date, used as evidence for reverse-charge invoicing.
What it is
A consultation number is a unique reference issued by VIES (the requestIdentifier field in the checkVatApprox SOAP response) when you query another company's VAT number and supply your own VAT number as the requester. It ties your query to a date and a result, so the tax authority of your member state treats the lookup as "consulted in good faith" for the purpose of applying reverse charge.
Where you meet it
You meet the consultation number in two places. First, in the VIES SOAP response: the requestIdentifier element appears only when the <requesterCountryCode> and <requesterVatNumber> inputs are present. Second, in your invoice archive: some member states require you to store the consultation number alongside the invoice as proof that the buyer's VAT number was confirmed valid at the time of supply. In vatverify's /v1/validate response, it is surfaced as consultationNumber when the upstream VIES call returned one.
Why it matters in audit
The consultation number is the audit-trail artifact that proves a seller exercised due diligence before zero-rating an intra-Community supply. If a tax administration later challenges whether the buyer's VAT number was valid at the time of the invoice, producing the consultation number and the matching VIES response is the strongest possible defence.
For German sellers under §18e UStG, the BZSt qualified confirmation produces an analogous artifact: a per-field match-code grid showing name, street, postcode, and town confirmations. The two systems coexist; a German seller invoicing a French buyer can rely on either or both depending on the audit posture they want to maintain.
Storage requirements
EU rules require sellers to retain VAT records for a minimum period set by each member state, typically 6 to 10 years. The consultation number is part of that record set. Persist it on the invoice header alongside the buyer VAT number, the date of supply, and the resulting tax treatment, so the full chain of evidence is reconstructible from the invoice alone.
vatverify's audit log on the Pro and Business plans stores the consultation number alongside the raw VIES payload by default; the audit log is exportable as JSON for archival into your accounting system.
Common confusions
- A plain
checkVatcall (no requester VAT number supplied) does not return a consultation number. You needcheckVatApproxwith both your country code and VAT number in the request. - The consultation number does not extend validity beyond the moment of the query. A buyer deregistering the next day still means the next sale needs a fresh check.
- A consultation number is not interchangeable with a BZSt qualified confirmation. The BZSt artifact is a per-field match-code grid; the VIES consultation number is a single opaque identifier referencing the moment of the lookup.