A practical breakdown of Germany's phased e-invoicing mandate, what it means for your application, and how to prepare before the 2027 deadline.

Germany is rolling out mandatory B2B e-invoicing in phases. If your application handles invoices for German businesses, you need to understand what's coming and when.

The Timeline

The Growth Opportunities Act (Wachstumschancengesetz) introduced a phased mandate:

January 1, 2025 — All businesses must be able to receive structured e-invoices. This is already in effect. If your application processes incoming invoices for German companies, you should already be handling XML invoices alongside traditional PDFs.

January 1, 2027 — Businesses with annual revenue exceeding €800,000 must send e-invoices in a structured format. Paper invoices and plain PDFs are no longer sufficient for B2B transactions.

January 1, 2028 — The sending requirement extends to all businesses, regardless of revenue.

What Counts as an E-Invoice?

A PDF attached to an email is not an e-invoice under the mandate. An e-invoice must be:

Structured — machine-readable XML following the EN 16931 European standard
Compliant — conforming to a recognized profile (XRechnung is the German standard)
Processable — recipients must be able to extract invoice data without manual entry

The accepted formats are:

XRechnung (UBL 2.1 or CII syntax) — the standard for German B2G invoicing, now extending to B2B
ZUGFeRD (Comfort or Extended profile) — a hybrid format embedding compliant XML inside a PDF/A-3

What This Means for Developers

If you build applications that generate, send, or receive invoices for German businesses:

Receiving (Now)

Your application should already detect and parse structured invoices from incoming email or file uploads. This means:

Scanning email attachments for XML files matching UBL or CII schemas
Checking PDFs for embedded ZUGFeRD metadata
Extracting structured data (invoice number, line items, tax amounts) for your internal systems

Sending (2027/2028)

When your application generates invoices, it will need to produce valid XRechnung XML:

Map your internal invoice data to EN 16931 business terms
Include all mandatory German fields (seller contact, Leitweg-ID for B2G, payment terms)
Validate the output against XRechnung Schematron rules before sending
Deliver the XML to recipients via email or Peppol

The Postscale Approach

Instead of implementing XML generation, Schematron validation, and format detection yourself, you can use the Postscale Invoices API:

Validation API — validate any XML invoice against EN 16931 and XRechnung rules
Send API — pass JSON, get a compliant XRechnung invoice generated and delivered via email
Inbound processing — automatically detect and extract e-invoices from incoming email

The validation endpoint is free to use — you can start checking your existing invoices for compliance today.

Germany's B2B E-Invoicing Mandate: What Developers Need to Know