Mandatory fields
German e-invoice mandatory fields: which fields must an e-invoice contain?
Short answer: a German e-invoice has to satisfy two layers. First, the classic invoice details required by § 14 UStG (seller, buyer, invoice number, date, supply, VAT). Second, exactly those details must be present structured and machine-readable in the XML under EN 16931 — in the defined business terms (BT) and business groups (BG). If a mandatory field is missing in the structured part, the invoice is not technically compliant even when the PDF image looks complete.
Layer 1: mandatory details under § 14 UStG
These content requirements apply unchanged to e-invoices — only their form changes (structured instead of free text):
- Full name and address of the supplier, and of the recipient.
- The supplier's tax number or VAT identification number (USt-IdNr.).
- Invoice issue date and a sequential, unique invoice number.
- Quantity and type of goods, or scope and type of the service, plus the date/period of supply.
- The net amount broken down by tax rate and any pre-agreed reductions.
- The applicable VAT rate and amount — or a note when the supply is exempt.
- Where relevant: a reverse-charge note ("Steuerschuldnerschaft des Leistungsempfängers"), a credit-note note ("Gutschrift"), or a retention-obligation note.
Small-value invoices up to €250 (§ 33 UStDV) have a reduced set, but a complete structured capture is still advisable because recipient systems and validators check the EN 16931 core.
Layer 2: the structured EN 16931 mandatory fields
EN 16931 models the invoice as business terms (BT) grouped into business groups (BG). XRechnung is the German CIUS of the norm; ZUGFeRD/Factur-X carry the same model in the EN 16931 profile. The key mandatory fields:
- Header: invoice number (BT-1), issue date (BT-2), invoice type code (BT-3: 380 invoice, 381 credit note), currency (BT-5), specification identifier of the profile (BT-24).
- Seller (BG-4): name (BT-27), address (BG-5), VAT identifier (BT-31) or tax registration (BT-32).
- Buyer (BG-7): name (BT-44) and address; for B2G also the buyer reference (BT-10).
- Invoice lines (BG-25): line id (BT-126), quantity (BT-129), net unit price (BT-146), item name (BT-153) and the assigned VAT category.
- VAT breakdown (BG-23): taxable amount (BT-116), tax amount (BT-117), category code (BT-118, e.g. S, Z, AE) and rate (BT-119).
- Totals (BG-22): sum of line net amounts (BT-106), total without VAT (BT-109), total with VAT (BT-112), amount due for payment (BT-115).
B2G special case: the Leitweg-ID is mandatory
For invoices to public authorities (B2G, typically XRechnung) the Leitweg-ID in the buyer reference (BT-10) is a hard mandatory field, required by the German rule BR-DE-15. If it is missing or malformed, receiving portals and the KoSIT validator reject the invoice. See Leitweg-ID in XRechnung.
German business rules (BR-DE) tighten the requirements
Beyond the EN 16931 core, XRechnung defines national rules (BR-DE-*) that require extra fields — for example seller contact details (BG-6: contact name BT-41, phone BT-42, email BT-43) and payment information. The official KoSIT validator checks exactly these, which is why an invoice can look correct yet still fail to reach "accept".
What fakturai checks (KoSIT-Accept-Gate)
The free validator is the fastest way to check whether the structured mandatory fields are present and whether the official KoSIT accept gate — including BR-DE rules — is reached. fakturai also generates ZUGFeRD/Factur-X with these fields and validates before delivery.
What fakturai does not replace (GHOA-1671)
fakturai checks technical format and structural compliance. The content and tax correctness of the invoice, proper archiving and accounting treatment remain your responsibility. fakturai is not tax advice and makes no legal, tax or financial guarantees.
Next step
Free German e-invoice validator
Related: E-invoice example (XML) · Validation checklist · Leitweg-ID · What is EN 16931?