US Billionaire Is First to Leave Heirs a Tax-Free Estate For the wealthy, year-long exemption makes 2010 a good year to die By Rob Quinn, Newser Staff Posted Jun 9, 2010 6:25 AM CDT 36 comments Comments John D. Rockefeller, seen here giving a nickel to a child in 1923, was America's first billionaire. His estate was taxed at 70% when he died in 1937. (Getty Images) (Newser) – Texas pipeline tycoon Dan Duncan couldn't have died at a worse time for the taxman—and the best time for his heirs' bank accounts. The philanthropist has become the first billionaire in American history to leave behind an estate untouched by taxes, thanks to a 1-year exemption in the estate tax. For every other billionaire, from John D. Rockefeller onwards, death has been followed by taxes; 70% in Rockefeller's case. Duncan left hundreds of millions of dollars of his $9 billion estate to his spouse and to various charities, all of which would have been untaxable, but the bulk of his estate went to his four children and four grandchildren and would have been taxed at 45%. The 2010 exemption was signed into law by George W. Bush as part of his package of tax cuts in 2001; Democrats pledged to rescind it but Congress failed to reach an agreement in time. The Senate Finance Committee is working to reinstate the tax but any effort to retroactively tax Duncan's estate is likely to meet a fierce court challenge, the New York Times notes.