E-invoicing: basics, formats and mandatory fields

What is an e-invoice?

An e-invoice is issued, transmitted and received in a structured electronic format that enables electronic processing. In practice this means formats that follow the European standard EN 16931. Other agreed formats are permitted as long as they allow the mandatory VAT details to be extracted correctly and completely.

The decisive difference is who the invoice is readable by. A conventional PDF is made for the human eye: a computer sees only text at image positions and has to guess the amounts through character recognition, or someone retypes them. A genuine e-invoice, by contrast, is an XML data model in which every piece of information sits in a defined field — its business term. The recipient system therefore finds the invoice number, the VAT rate and the amount due in exactly the same place as in every other e-invoice, and can check and post them without a break in the media chain.

For you as the issuer, less changes than the term suggests: you enter the same information as before. Your software additionally produces the structured file from it.

Other invoices and e-invoices compared

Until the end of 2024, any invoice sent electronically counted as an electronic invoice, a plain PDF included. Since 1 January 2025 German VAT law distinguishes between the structured e-invoice and the "other invoice" — paper, image files, and the familiar PDF.

The German e-invoicing mandate: deadlines and who is covered

The German B2B e-invoicing mandate covers taxable transactions between domestic entrepreneurs. What matters is the VAT obligation to issue an invoice, the domestic establishment of both parties, and the statutory exceptions. It does not apply to sales to consumers.

Keep the receiving side and the issuing side strictly apart: you have had to be able to receive e-invoices since 1 January 2025, without exception and regardless of your size. Issuing your own e-invoices is governed by transitional rules that depend on your previous-year revenue.

1. from 1 Jan 2025

   Everyone must be able to receive

   Every domestic business must be able to accept e-invoices. Formally, an email inbox is enough according to the ministry FAQ; in practice you also need a way to read the XML file, check it and file it traceably.

2. until 31 Dec 2026

   General transitional period for issuing

   Issuers may still send paper invoices. A simple electronic format such as a PDF requires the recipient to agree.

3. from 1 Jan 2027

   Issuing required above 800,000 euros previous-year revenue

   Businesses with more than 800,000 euros of revenue in the previous year must issue e-invoices for the covered domestic B2B transactions. Below that threshold the transitional rule runs one year longer.

4. from 1 Jan 2028

   E-invoicing becomes the default

   The extended deadline for smaller issuers ends too. From then on only the statutory exceptions remain, such as small-value invoices and supplies by small businesses.

Standards and formats: EN 16931, XRechnung, ZUGFeRD and Peppol

The European standard EN 16931 defines the semantic data model of an electronic invoice: which pieces of information exist, what they are called, and how they relate to each other. It does not prescribe a file format — which is why several formats satisfy the same standard while looking quite different.

• EN 16931 — the European standard

  Describes the semantic core model with its business terms and business rules. Profiles and national rules may add further requirements on top.

• XRechnung — the pure XML format

  The German application specification (CIUS) of the standard, issued in UBL or CII syntax. It carries no visual rendering and is the standard for dealings with public administration.

• ZUGFeRD / Factur-X — the hybrid format

  Combines a visible PDF/A-3 file with an embedded XML invoice. The recipient sees a familiar invoice while their software reads the structured data — the most convenient route in B2B.

• Peppol BIS Billing and EDI

  Peppol is less a format than a transmission network with its own profile based on the standard. Classic EDI procedures may continue under certain conditions and once aligned with EN 16931.

Which format fits a given transaction is not decided by the format alone but by what your recipient requires. The detailed comparison lives on the ZUGFeRD and XRechnung page.

BT numbers: how an e-invoice is built

So that a recipient system can process an invoice without asking questions, every piece of information is assigned to a defined field. EN 16931 calls these fields business terms (BT) and collects them into business groups (BG). Business rules (BR) then specify which fields must appear together and how the totals add up.

These numbers are why error messages from validation portals look like "BR-DE-15" or "BT-10 is missing". Once the system clicks, such a message reads like an address: the BR says which rule was broken, the BT says in which field.

A selection of the business terms that matter in almost every compliant e-invoice. Each BT number links to its own reference page.

Further fields that appear depending on the case

• BT-20 — payment terms

  Payment terms in plain text, early-payment discounts and deviating arrangements.

• BT-42 / BT-43 — seller contact

  Telephone number and email address of the contact person; XRechnung requires BT-43.

• BT-92 / BT-107 — document level allowances

  A single document-level allowance and the sum of all allowances.

• BT-116 ff. — VAT breakdown

  Taxable base, rate and amount per VAT category — the most common source of errors on invoices with mixed rates.

• BT-134 / BT-135 — line invoicing period

  Relevant for recurring services such as maintenance, rent or subscriptions.

• BT-7 / BT-72 — tax point and delivery date

  A deviating VAT point in time and the actual delivery date.

This overview is a selection from the semantic core model and deliberately not a complete list. How binding a field is depends on the invoice type, the profile in use and the national specification — XRechnung makes more fields mandatory than the bare standard does.

What the change delivers in day-to-day work

Structured invoice data simplifies processing — how much depends on your current workflow and on how well the systems involved are connected. The points below describe where the difference usually appears.

• Less data entry

  Electronic delivery saves paper, printing and postage; above all it removes the retyping of incoming invoices. How much time that saves depends on the process you have today.

• Import instead of input

  Compatible systems read the invoice data directly. That reduces manual entry and follow-up questions; reviewing and approving the invoice remains your job.

• Fewer transcription errors

  Structured data and formal validation catch transposed digits and missing mandatory fields before the invoice leaves the building.

• Traceable filing

  E-invoices can be organised digitally and compactly. Billance supports you with local storage, an archive and backups; proper retention and process documentation remain part of your own operations.

• Faster incoming payments

  An invoice that lands directly in the recipient’s approval flow is paid earlier on average than one that has to be captured first. That works straight through to your liquidity.

• Groundwork for ViDA

  Producing standard-compliant invoice data today gives you the basis for the European reporting duties that are coming.

Creating an e-invoice: the workflow in four steps

With the right software, the path to an e-invoice barely differs from writing an invoice the way you always have. The difference sits in steps two and three: validation and format.

1. 1

   Enter the invoice data

   Fill in the usual details: seller and buyer including VAT identifiers, line items, prices and tax rates. For public buyers, the routing identifier they give you goes into the buyer reference (BT-10).

2. 2

   Validate formally against EN 16931

   Billance checks in the background whether the mandatory fields are filled and whether the tax and total calculations add up. Formal checks do not replace the professional and tax review.

3. 3

   Choose a format and generate it

   For public authorities you produce an XRechnung as XML; for business customers a ZUGFeRD hybrid PDF is usually the better fit. Existing PDF invoices can be converted into an e-invoice format.

4. 4

   Send and retain

   Email is the most common route. Afterwards keep the structured original unaltered and file it traceably in your invoice management.

Check, read and unpack e-invoices right away

You do not need to install anything to work with an e-invoice. The three tools below run entirely in your browser: your invoice file is never sent to a server, there is no account and no limit.

• View an e-invoiceOpen an XRechnung XML or a ZUGFeRD PDF and read parties, line items, taxes and totals in a clear layout.
• Validate an e-invoiceA validation report covering XML schema, EN 16931, XRechnung and Peppol — with findings that point at BT and BR numbers.
• Extract XML from an e-invoiceInspect and download the embedded invoice XML from one or many ZUGFeRD or Factur-X PDF files.

Frequently asked questions about e-invoicing

The questions that come up most often in practice — from the PDF question to retention.

Sources and further reading

The statements on this page rest on the publicly available publications below. In case of doubt, the original text governs.

• E-invoicing: questions and answers on the B2B rollout — German Federal Ministry of Finance
• German VAT Act § 14 — issuing invoices — Federal Office of Justice, Gesetze im Internet
• XRechnung: standard, specification and validator configuration — KoSIT — German coordination office for IT standards
• ZUGFeRD and Factur-X: format specification and profiles — FeRD — Forum elektronische Rechnung Deutschland
• EN 16931: semantic data model of the electronic invoice — European Commission — Digital Building Blocks
• VAT in the Digital Age (ViDA) — European Commission

This article reflects publicly available information as of the date shown and is not tax or legal advice. What governs are the statutory rules, the letters issued by the German Federal Ministry of Finance and the requirements of your invoice recipient.

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