XInvoice is a standard format for electronic invoices in Germany. It was developed to simplify and standardise the exchange of invoice data between companies and the public administration. 

XInvoice specifies certain data fields and structures that must be included in an electronic invoice. This includes information such as invoice number, invoice date, supplier data, invoice amount and VAT details. The format also allows for the attachment of other documents such as invoice attachments or order confirmations. In fact, XInvoice is a document in the form of an XML file that contains all the information just mentioned for an invoice. It is just written differently in machine language, which seems cryptic to a layman.

The introduction of XInvoice in Germany was driven by the E-Invoice Act. This law obliges public clients to accept electronic invoices in XInvoice format. It affects federal authorities as well as state and local authorities.

With the European standard for electronic invoicing EN-16931, the EU has decided on a measure for how eInvoices should be designed in the future. The XInvoice standard has been operated by the Coordination Office for IT Standards (KoSIT) since 1 January 2019. The currently valid version can be found on the KoSIT website.