When thinking of tax havens, one generally pictures notorious zero-tax Caribbean islands like the Cayman Islands and Bermuda. However, we can also find a tax haven a lot closer to home in the state of Delaware – a choice location for U.S. business formation. A loophole in Delaware’s tax code is responsible for the loss of billions of dollars in revenue in other U.S. states, and its lack of incorporation transparency makes it a magnet for people looking to create anonymous shell companies, which individuals and corporations can use to evade an inestimable amount in federal and foreign taxes. The Internal Revenue Service estimated a total tax gap of about $450 billion with $376 billion of it due to filers underreporting income in 2006 (the most recent tax year for which this data is available).[i] While it is impossible to know how much underreported income is hidden in Delaware shell companies, the First State’s ability to attract the formation of anonymous companies suggests that it could rival the amount of income hidden in more well-known offshore tax havens.