In its December 2008 report on the use of tax havens by American corporations, the U.S. Government Accountability Office was unable to find a satisfactory definition of a tax haven but regarded the following characteristics as indicative of it: nil or nominal taxes; lack of effective exchange of tax information with foreign tax authorities; lack of transparency in the operation of legislative, legal or administrative provisions; no requirement for a substantive local presence; and self-promotion as an offshore financial center.