Richtlinie 2006/112/EU des Rates vom 28. November 2006 zum gemeinsamen Mehrwertsteuersystem
Die ursprüngliche "E-Invoicing"-Richtlinie 2001/115/EG des Rates, vom 20. Dezember 2001 mit dem Ziel der Vereinfachung, Modernisierung und Harmonisierung der mehrwertsteuerlichen Anforderungen an die Rechnungstellung ist per 28. November 2006 in obige Richtlinie integriert worden.

OECD Tax Guidance Series - Transaction Information Guidance
The purpose of this note is to encourage appropriate guidance on transaction information for businesses offering services or products via the Internet. The paper is written from an audit perspective—to ensure that an appropriate amount of information exists in the transaction so as to enable verification of the tax results arising from the transaction or aggregated series of transactions. While written for the emerging electronic commerce environment, it applies equally to traditional business transactions using electronic systems.

Wegleitung der OECD für Entwickler von Business- und Buchhaltungs-Software betreffend Anforderungen der Steuerprüfung
The OECD’s Committee on Fiscal Affairs (CFA) recently approved two notes arising from work to develop a set of guidance on business accounting system data requirements for tax audit purposes, and associated practical implementation issues for software developers. The set of guidance was prepared by a task group consisting of representatives of national revenue authorities, the Business Applications Software Developers Association (BASDA), accounting bodies, and other interested parties.