# ZUGFeRD BT Fields: Business Terms for Practical E-Invoicing - Date: 2025-01-18 - Reading time: 10 min read Understand ZUGFeRD BT fields, field mappings, validation rules, and implementation checks for German and EU electronic invoicing standards. ## Article overview This article explains ZUGFeRD BT Fields: Business Terms for Practical E-Invoicing as a practical reference for European e-invoicing. It defines the topic in plain language, places it in the compliance context, and connects the explanation to invoice formats such as XRechnung, ZUGFeRD/Factur-X, UBL, and CII. Use the article as a starting point before changing a finance or ERP workflow: identify the applicable country rule or standard, decide which structured format is expected, validate the generated XML, and keep a documented exception process for invoices that require manual review. ## Understanding ZUGFeRD BT Fields in Practice ZUGFeRD invoices use EN 16931 Business Terms, usually shortened to BT fields. These fields define the invoice data that software validates and exchanges: invoice number, seller, buyer, totals, VAT treatment, payment details, and line information. At **Invoice-Converter.com**, we handle BT field mapping automatically when converting between PDF, XRechnung, and ZUGFeRD formats, ensuring your invoices always meet compliance requirements. ### Quick Reference - **BT** = Business Terms (standardized data elements) - **EN 16931** = European e-invoicing standard - **400+ BT fields** defined in the standard - **Mandatory vs. Optional** fields for compliance ### What Are BT Fields? BT fields (Business Terms) are standardized data elements defined by the European standard EN 16931. Each BT field has a unique identifier (e.g., BT-1, BT-2) and represents specific invoice information such as invoice number, date, supplier details, or tax amounts. These fields ensure that electronic invoices can be processed automatically across different systems and countries. ### Essential BT Fields Every Business Should Know #### Core Invoice Information - **BT-1: Invoice number** - Unique identifier for the invoice - **BT-2: Invoice issue date** - Date when the invoice was created - **BT-3: Invoice type code** - Type of invoice (380 = Commercial invoice, 381 = Credit note) - **BT-5: Invoice currency code** - Currency of the invoice (e.g., EUR, USD) - **BT-6: VAT accounting currency code** - Currency for VAT calculations #### Supplier Information (Seller) - **BT-27: Seller name** - Legal name of the supplier - **BT-28: Seller trading name** - Commercial name if different - **BT-29: Seller identifier** - Company registration number - **BT-31: Seller VAT identifier** - VAT registration number - **BT-32: Seller tax registration ID** - Tax ID if no VAT number #### Buyer Information - **BT-44: Buyer name** - Legal name of the buyer - **BT-45: Buyer trading name** - Commercial name if different - **BT-46: Buyer identifier** - Company registration number - **BT-48: Buyer VAT identifier** - VAT registration number - **BT-10: Buyer reference** - Purchase order or reference number #### Payment Information - **BT-9: Payment due date** - Date when payment is due - **BT-81: Payment means type code** - How payment should be made - **BT-83: Remittance information** - Payment reference - **BT-84: Payment account identifier** - IBAN or account number - **BT-86: Payment service provider identifier** - BIC or bank code ### BT Fields for Tax Calculations BT Field Description Example BT-106 Sum of Invoice line net amount 1000.00 BT-110 Invoice total VAT amount 190.00 BT-112 Invoice total amount with VAT 1190.00 BT-115 Amount due for payment 1190.00 ### Line Item BT Fields Each invoice line has its own set of BT fields for detailed product or service information: - **BT-126: Invoice line identifier** - Unique line number - **BT-129: Invoiced quantity** - Number of units - **BT-130: Invoiced quantity unit of measure** - Unit code (e.g., C62 for pieces) - **BT-131: Invoice line net amount** - Total excluding VAT - **BT-146: Item net price** - Price per unit - **BT-151: Item VAT category code** - VAT rate category ### Mandatory vs. Optional BT Fields #### Compliance Requirements **Mandatory fields** must always be present for a valid invoice: - Invoice number (BT-1) - Invoice issue date (BT-2) - Invoice type code (BT-3) - Invoice currency code (BT-5) - Seller name (BT-27) - Buyer name (BT-44) - Invoice line net amount (BT-131) - Invoice total amounts (BT-106, BT-110, BT-112) **Optional fields** provide additional information when needed: - Purchase order reference (BT-13) - Contract reference (BT-12) - Project reference (BT-11) - Delivery date (BT-72) ### Common BT Field Validation Rules - **Format validation:** Dates must be in YYYY-MM-DD format - **Code list validation:** Currency codes must be valid ISO 4217 codes - **Calculation validation:** Total amounts must match sum of line items - **Conditional rules:** If VAT exempt, exemption reason must be provided - **Cross-field validation:** Payment due date must be after invoice date ### BT Field Mapping Between Formats When converting between different e-invoice formats, BT fields serve as the common language: BT Field XRechnung (UBL) ZUGFeRD (CII) BT-1 cbc:ID rsm:ExchangedDocument/ram:ID BT-2 cbc:IssueDate ram:IssueDateTime BT-27 cac:PartyName/cbc:Name ram:Name ### Best Practices for BT Field Implementation - **Use standardized code lists:** Always use official code values for countries, currencies, and units - **Validate early and often:** Check BT field compliance before sending invoices - **Maintain data quality:** Ensure accurate and complete information in all fields - **Document custom extensions:** If using additional fields, document them clearly - **Test with trading partners:** Verify that your BT field usage matches partner expectations ### Common BT Field Errors and Solutions #### Frequent Mistakes - **Missing mandatory fields:** Always check that all required BT fields are populated - **Invalid date formats:** Use ISO 8601 format (YYYY-MM-DD) consistently - **Incorrect VAT calculations:** Ensure BT-110 equals sum of all VAT amounts - **Wrong currency codes:** Use three-letter ISO codes (EUR, not €) - **Mismatched totals:** Line item sum must equal invoice subtotal ### BT Fields and German Compliance For German e-invoicing compliance, additional considerations apply: - **Leitweg-ID (BT-10):** Required for all B2G invoices in Germany - **German tax number formats:** Must follow specific patterns for BT-32 - **Payment terms:** Skonto (cash discount) must be clearly specified - **Reverse charge indicators:** Special coding for VAT-exempt B2B services ### Automated BT Field Processing Modern e-invoicing systems like **Invoice-Converter.com** handle BT fields automatically: - Extract data from PDF invoices and map to correct BT fields - Validate all mandatory fields are present and correctly formatted - Calculate dependent fields (totals, VAT amounts) automatically - Convert between different XML syntaxes while preserving BT field data - Generate human-readable PDFs from BT field data ### Future of BT Fields The BT field standard continues to evolve with e-invoicing requirements: - **New fields for sustainability:** Carbon footprint and environmental data - **Enhanced payment information:** Support for instant payments and cryptocurrencies - **Supply chain integration:** Links to logistics and inventory systems - **Real-time reporting:** Fields for immediate tax authority submission #### Ready to Master BT Fields? Let Invoice-Converter.com handle the complexity of BT field mapping and validation for you. Our advanced conversion engine ensures: - Automatic extraction and mapping of all BT fields - Validation against EN 16931 and German requirements - Controlled conversion between formats - Clear error messages for missing or invalid fields ## How to use this guide Use the article as a starting point before changing a finance or ERP workflow: identify the applicable country rule or standard, decide which structured format is expected, validate the generated XML, and keep a documented exception process for invoices that require manual review.