# BT-31 — Seller VAT identifier

> https://billhorse.com/en/terms/bt-31/

The seller's VAT identification number including the country prefix (e.g. DE123456789). In UBL, TaxScheme/ID = VAT marks this field; in CII the schemeID attribute VA does.

## Practical note

French VAT numbers follow the pattern FR + 2 check characters + 9-digit SIREN; the last 9 digits must match the SIREN in BT-30.

## Where does it live in the XML?

- UBL: `cac:AccountingSupplierParty/cac:Party/cac:PartyTaxScheme/cbc:CompanyID (TaxScheme/ID = VAT)`
- CII: `rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:SellerTradeParty/ram:SpecifiedTaxRegistration/ram:ID (schemeID VA)`

## Checked by these rules

- [BR-CO-26 — Seller tax identifier missing](https://billhorse.com/en/rules/br-co-26/)
- [BH-FR-04 — French VAT number invalid](https://billhorse.com/en/rules/bh-fr-04/)
- [BH-FR-05 — SIREN in VAT number contradicts BT-30](https://billhorse.com/en/rules/bh-fr-05/)