What is an e-invoice?

E-invoice: definition and formats

An e-invoice contains all invoice data in a machine-readable data set, such as invoice number, amounts, tax rates and line items. The basis is the European standard EN 16931. A PDF sent by email or a scanned paper document is therefore not an e-invoice within the meaning of the German VAT Act, even if it is transmitted electronically.

Two formats are widespread in Germany: XRechnung is a pure XML file used mainly in dealings with public authorities. ZUGFeRD is a hybrid format combining a readable PDF/A-3 with an embedded XML data set. For tax recognition, the profile must comply with the standard; the simplest profiles (“Minimum” and “Basic WL”) are not sufficient.

Deadlines: what has applied since 2025

Since January 1, 2025, all domestic businesses must be able to receive and read e-invoices in B2B transactions. For issuing, a transition period applies: until the end of 2026, paper invoices and, with the recipient’s consent, other electronic formats such as PDF may still be used. From January 1, 2027, businesses with more than €800,000 in prior-year turnover must issue e-invoices, and from January 1, 2028, all businesses must.

• Small-amount invoices up to €250 are exempt
• Tickets for passenger transport are exempt
• Invoices to private customers (B2C) are not affected
• Small businesses under the VAT exemption must receive, but need not issue, e-invoices

Real-world example: a supplier changes its invoicing process

A supplier with 40 employees has so far received incoming invoices as PDFs by email and typed them into the accounting software by hand. It sets up a central invoice mailbox, has its ERP system and DATEV connection read and check e-invoices, and defines who approves invoices.

For sending, it switches its invoice output to ZUGFeRD, tests the format with two customers and archives the file in its original form. This way, it is ready before the issuing obligation for larger businesses takes effect in 2027, and saves effort in the long run, because invoice data no longer has to be transferred by hand.

Benefits, limits and common mistakes

Benefits are less retyping, faster checks and the basis for automation. Limits come from format diversity and coordination with customers and suppliers. Invoices must also be archived under the GoBD (the German principles for proper digital bookkeeping and record retention) in an unalterable, machine-readable way, generally for eight years.

• A PDF sent by email does not count as an e-invoice
• Archive the original XML, not just the visual rendering
• Observe mandatory details such as the Leitweg-ID for public authorities
• Map credit notes, advance payments and cancellations in the same format
• Organize invoice receipt centrally and traceably

What companies should look out for

Check whether your accounting, ERP or shop software can create and read e-invoices, and coordinate the approach with your tax advisor. Important are GoBD-compliant archiving, a clean process for receipt and approval and, where applicable, interfaces to DATEV. Nano Concepts develops e-invoicing interfaces and automations. This article does not replace legal advice.