Reference
Markdown exportBT-31 Seller VAT Identifier
The seller's VAT identifier (also known as VAT registration number). For German companies, this follows the format DE + 9 digits.
BT-31 is the seller's VAT identifier. It is conditional. Select BT-31, BT-32, or BT-63 according to the VAT category; category O forbids BT-31. Example: DE123456789.
BT-31 · EN 16931 / XRechnung 3.x
BT Reference Card
Key EN 16931 and XRechnung facts for this business term.
- BT code
BT-31- Name
- Seller VAT Identifier
- Cardinality
- Conditional (C)
- Business group
- BG-4 SELLER
- Data type
- Identifier
- Example value
DE123456789- Common error
- BR-CO-09 checks the VAT country prefix when BT-31 is present; it does not require BT-31. The VAT-category rules decide whether BT-31, BT-32, or BT-63 is needed.
Seller details
Who issued the invoice and how the recipient can identify that business reliably.
Quick actions
In plain language
The seller's VAT identifier (also known as VAT registration number). For German companies, this follows the format DE + 9 digits.
Use BT-31 when the VAT category rules require the seller VAT identifier. Depending on the category, BT-32 or BT-63 can be an alternative. Category O forbids BT-31.
What you usually enter here
Country code (2 letters) + national VAT number
Typical valid values include: DE123456789, ATU12345678, FR12345678901, NL123456789B01
BT-31 is conditional. BR-CO-09 checks the country prefix when a VAT identifier is present; it does not require this field. The VAT category rules determine which seller tax identifier is needed.
Where the field sits
- Invoice
- cac:AccountingSupplierParty
- cac:Party
- cac:PartyTaxScheme[cac:TaxScheme/upper-case(cbc:ID)="VAT"]
- cbc:CompanyIDBT-31
- rsm:CrossIndustryInvoice
- rsm:SupplyChainTradeTransaction
- ram:ApplicableHeaderTradeAgreement
- ram:SellerTradeParty
- ram:SpecifiedTaxRegistration
- ram:ID[@schemeID="VA"]BT-31
What goes wrong often
Avoid values like: 123456789, DE12345678, DE1234567890, DE 123456789
Relevant rule codes: BR-CO-09, BR-DE-16, BR-S-02, BR-Z-02, BR-E-02, BR-AE-02, BR-G-02, BR-IC-02
Valid Examples
- DE123456789
- ATU12345678
- FR12345678901
- NL123456789B01
- IT12345678901
Invalid Examples
- 123456789
- DE12345678
- DE1234567890
- DE 123456789
- de123456789
XML mapping and field facts
Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.
Field ID:
BT-31
Data Type:
identifier
Cardinality:
0..1
Requirement:
Optional
Max Length:
30 characters
XML Implementation
/Invoice/cac:AccountingSupplierParty/cac:Party/cac:PartyTaxScheme[cac:TaxScheme/upper-case(cbc:ID)="VAT"]/cbc:CompanyID/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:SellerTradeParty/ram:SpecifiedTaxRegistration/ram:ID[@schemeID="VA"]Validation Rules
BR-CO-09
BR-CO-09
BR-DE-16
BR-DE-16
BR-S-02
BR-S-02
BR-Z-02
BR-Z-02
BR-E-02
BR-E-02
BR-AE-02
BR-AE-02
BR-G-02
BR-G-02
BR-IC-02
BR-IC-02
Next step
Check whether your XRechnung sets BT-31 correctly
Upload the XML file to the free validator. It applies the KoSIT rules for XRechnung 3.0 and names each finding with its rule ID, for this field for example BR-DE-16, BR-CO-09. Creating a new invoice instead? The converter checks the invoice against the same rules and shows the findings before download.
Free, no account needed. XML file up to 2 MB.
FAQ
What is the format for German VAT identifiers?
German VAT identifiers follow the format "DE" followed by exactly 9 digits (e.g., DE123456789). No spaces or special characters are allowed.
Is the VAT identifier mandatory for all sellers?
No. The VAT category determines the requirement. Some categories accept BT-32 or BT-63 instead, while category O forbids BT-31.
How can I validate a VAT identifier?
Use the EU VIES system (ec.europa.eu/taxation_customs/vies/) to validate VAT identifiers. Each country has specific format requirements.
What about other EU countries VAT formats?
Each EU country has its own VAT number format: ATU plus 8 digits, FR with 11 characters, NL with 12 characters, or IT with 11 digits. Use the full national VAT prefix and value.