In 2005, the Mozilla Foundation and Mozilla Corporation had a combined revenue of US$52.9 million, with approximately 95 percent derived from search engine royalties. In 2006, the Mozilla Foundation and Mozilla Corporation had a combined revenue of US$66.9 million, with approximately 90 percent derived from search engine royalties. In 2007, the Mozilla Foundation and Mozilla Corporation had a combined revenue of US$75 million, with 88 percent of this sum (US$66 million) from Google. Mozilla Foundation is being audited by the IRS and some believe its non-profit status may be called into question.