Companies around the world are increasingly expected to report their greenhouse gas emissions. Currently there are various formulas to calculate emissions, and there are different reporting formats. Most of the reporting formats are paper-based or non-readable-by-machine formats. The emissions of companies will influence their accounting results due to 'cap & trade' systems or environmental taxes. Analyses of financial impacts are important for management decisions and corporate evaluations by interested third parties. A standardized reporting format for GHG (greenhouse gas) emissions is critical for reliable analysis of the impact of emissions on finances. This paper proposes an XBRL (eXtensible Business Markup Language) format as the foundation for standardizing the emissions reporting formats, and provides a preliminary XBRL taxonomy for emissions reporting. XBRL makes it possible to combine the financial reports and the emissions reports. Evaluations of the emissions impact are easier for both managers of the company and external parties, even if a large number of emissions reports must be analyzed. © 2011, IGI Global.