Since 27 November 2020, with just a few exceptions, suppliers to the German federal administration have been required to send their invoices electronically. Information on e-invoicing at federal level is available here.
By contrast, Germany’s federal states are responsible for their own e-invoicing measures. This means that you, as a supplier, may have to deal with varying requirements when it comes to sending e-invoices. These requirements are determined by the laws of the federal state(s) in question.
This page provides you with initial information on e-invoicing in Germany’s federal states.