What are E-Invoices?

Starting in 2025, businesses in Germany must be able to receive e-invoices. From 2027 and 2028 onwards, they’ll also need to issue them. Billy helps you do that—enter your details, get a ready-to-send XRechnung.

But what actually is an e-invoice? And who needs to do what, and when? Here’s the short version.

An e-invoice is not a PDF

This is the most common misconception. A lot of people already send their invoices as PDFs via email and assume that counts. It doesn’t.

A real e-invoice is an XML file with structured data—not an image, not text for a human to read, but data that software can process directly.

There are two common formats in Germany:

XRechnung: Pure XML—no layout, but 100 % machine-readable
ZUGFeRD: PDF + XML in one file. Humans can read it, software can too.

Both are based on the EU standard EN 16931. Billy generates both XRechnung and ZUGFeRD files. Since ZUGFeRD is both human-readable and machine-readable, it serves as the default export method in the app.

When does what become mandatory?

The Wachstumschancengesetz (Growth Opportunities Act, March 2024) set the deadlines. Here’s the short version:

January 1, 2025 (already in effect)

Every business in Germany must be able to receive e-invoices. Meaning: if someone sends you an XRechnung, you need to be able to handle it.

January 1, 2027

Businesses with annual revenue above €800,000 must issue e-invoices. A PDF won’t cut it anymore.

January 1, 2028

Applies to everyone. Regardless of size or industry.

What’s exempt?

Invoices to private individuals (B2C)
Small-amount invoices under €250
Travel tickets
Tax-exempt services (doctors, insurance etc. under § 4 UStG)

And in case you’re wondering: yes, small business owners under § 19 UStG are also subject to the issuing requirement. The obligation is tied to your status as a business, not to whether you charge VAT.

FAQ

Which e-invoice format should I use?
Both XRechnung and ZUGFeRD comply with the legal requirements for e-invoices, but if you’re unsure which format to use, ZUGFeRD is a good choice as it’s both human-readable and a compliant e-invoice.

Where is my branding when I use XRechnung?
Because the XRechnung format is just an XML file, there is no visual layer that is meant for humans—just structured data to be processed by accounting software. If you want an additional human-readable layer, use ZUGFeRD.

Where is my e-invoice when I use ZUGFeRD?
A ZUGFeRD file looks like a usual PDF document, but has an e-invoice hidden inside—it doesn’t get picked up by normal PDF viewers, but can get read by accounting software.

Are there any drawbacks to using a ZUGFeRD PDF instead of a plain PDF?
Not really. If just you always use ZUGFeRD PDFs, you comply with the legal requirements for e-invoices, and your customers can easily read the invoice.

How do I send an XRechnung?
Just attach it to an email. The file ends in .xml. No portal needed—unless you’re invoicing a federal authority, in which case it goes through the Central Invoice Receipt Platform (ZRE).

My recipient can’t read the XML file.
That’s normal—XML isn’t meant for humans. There are free viewers that display the XML in a readable way. Otherwise, you can of course just use the ZUGFeRD format, which, like any other PDF, is human-readable.

How long do I need to keep e-invoices?
10 years. And in an unalterable, machine-readable format—a folder in your email inbox doesn’t count. You’ll need a GoBD-compliant archiving solution. Billy’s Auto-Export feature can help you automatically store completed invoices.