# VAT ID

Tax identifier used for VAT reporting and cross-border trade in the EU.

## Definition

Tax identifier used for VAT reporting and cross-border trade in the EU.

## Why this term matters

A valid VAT ID is what enables intra-EU reverse-charge under Article 138 of the VAT Directive and what tax authorities cross-check against VIES. Sending an invalid or unverified VAT ID on a cross-border B2B invoice exposes the supplier to retroactive VAT charges plus penalties, even when the buyer is genuinely VAT-registered.

## Explanation

Often required in B2B e-invoices and for reverse-charge scenarios.

May be used as part of PEPPOL Participant IDs (scheme-dependent).

## Common mistakes

- Confusing the VAT ID (BT-31, e.g., DE123456789) with the local tax registration number (BT-32) or the company registration number (BT-30).
- Failing to prefix the country code — VIES rejects "123456789" but accepts "DE123456789".
- Storing the VAT ID without VIES verification, then issuing a reverse-charge invoice to a buyer whose VAT ID was deregistered last quarter.
- Putting a personal/seller-only tax ID into the buyer VAT ID field on B2C invoices — the VAT ID elements should simply be omitted for unidentified consumers.

## Frequently asked questions

### How do I verify a VAT ID?
Use the EU VIES service (ec.europa.eu/taxation_customs/vies) which exposes a SOAP and REST API. Most ERPs and invoicing platforms can call it on every new customer record and store the verification timestamp for audit purposes.

### Where does the VAT ID go in EN 16931?
Seller VAT ID is BT-31 (cac:PartyTaxScheme/cbc:CompanyID with schemeID="VAT" in UBL). Buyer VAT ID is BT-48. The country code prefix is part of the value, not a separate attribute.

### Is the VAT ID always required on a B2B invoice?
For domestic B2B with reverse charge or for any intra-EU B2B supply where VAT is shifted to the buyer, yes. For pure domestic B2B without reverse charge, jurisdictions like Germany require it for invoices above €250 (§14 UStG); below that threshold the small-invoice rules apply.

## Related resources

- [VAT categories](/resources/glossary/tax-category)

## Related terms

- [Participant ID](/resources/glossary/participant-id): Identifier used in PEPPOL to address a sender/receiver (e.g., with a scheme).
- [Reverse charge](/resources/glossary/reverse-charge): VAT mechanism where the buyer accounts for VAT instead of the seller.
- [Tax category](/resources/glossary/tax-category): Classification of tax treatment (e.g., standard, exempt, zero-rated).