Mr Buffett explained that, like many top earners, his income came entirely from investments rather than from employment, which are subject to lower taxes in the US.
He said last year he paid an effective tax rate of 17.4%, less than the 33% to 41% paid by the employees in his office.
He dismissed arguments made by senior Republicans, including John Boehner, speaker of the House of Representatives, that taxing higher earners more would damage investment and job creation in the US.
“I have yet to see anyone… shy away from a sensible investment because of the tax rate on the potential gains,” he said.