The use of fully digital means of transmitting, receiving and handling financial messages between companies and public institutions are becoming increasingly common and is indeed already required by some public institution, particularly in the European Union. The standard used for the EU is the Pan-European Public Procurement Online (PEPPOL), which provides a framework for how invoices, orders and other financial messages, are not only to be transmitted but also encoded in a standardised way, so that they can be ’read’ by the receiving system, without the need for manual human intervention. This paper describes a design and implementation of a program that will convert invoices and other financialmessages from Odoo, a business management program, into PEPPOL, as well as convert from PEPPOL to Odoo. With this experience as a basis, general problems which may occur when converting from and to PEPPOL are discussed, such as the problem of understanding the PEPPOL description’s financial language, and the more specific problems which occur with Odoo, specifically the problem of validating XML files of XSLT 2.0 and higher in Odoo.