 Effective June 2008, US citizens who renounce their citizenship are subject under certain circumstances to an expatriation tax, which is meant to extract, from the expatriate, taxes that would have been paid had he or she remained a citizen.All property of a covered expatriate is deemed sold for its fair market value on the day before the expatriation date, which usually results in a capital gain, which is taxable income.Eduardo Saverin, a Brazilian-born co-founder of Facebook, renounced his US citizenship just before the company's expected initial public offering.