Billionaire investor Warren Buffett has revived his calls for increased taxes on the wealthy in the op-ed pages of The New York Times.

In a new op-ed that appeared Sunday entitled, “A Minimum Tax for the Wealthy,” Buffett follows up on an earlier editorial, “Stop Coddling the Super-Rich,” which appeared in August 2011. Buffett suggested that the super-rich should not be paying lower tax rates than their employees, which prompted President Obama to propose the so-called Buffett Rule (see Buffett Says Tax Code is 'Coddling the Super-Rich').

In his latest editorial, Buffett proposes a minimum tax rate on the ultrarich. He noted that the taxes paid by the 400 people with the highest incomes in the U.S. averaged only 19.9 percent of their adjusted gross income in 2009, down from 26.4 percent in 1992. More than a quarter of them paid less than 15 percent in combined federal income and payroll taxes, he added, while some of them paid no taxes at all.

“This outrage points to the necessity for more than a simple revision in upper-end tax rates, though that’s the place to start,” Buffett wrote.

He said he supports President Obama’s proposal to eliminate the Bush tax cuts for high-income taxpayers, although he added that he prefers a cutoff point above $250,000, perhaps $500,000.

“Additionally, we need Congress, right now, to enact a minimum tax on high incomes,” Buffett wrote. “I would suggest 30 percent of taxable income between $1 million and $10 million, and 35 percent on amounts above that. A plain and simple rule like that will block the efforts of lobbyists, lawyers and contribution-hungry legislators to keep the ultrarich paying rates well below those incurred by people with income just a tiny fraction of ours. Only a minimum tax on very high incomes will prevent the stated tax rate from being eviscerated by these warriors for the wealthy.”

Buffett added that such changes should not be delayed by efforts to reform the Tax Code and said he was in favor of eliminating the carried interest tax break that enables “income from labor to be magically converted into capital gains.”

“And it’s sickening that a Cayman Islands mail drop can be central to tax maneuvering by wealthy individuals and corporations,” Buffett added. “But the reform of such complexities should not promote delay in our correcting simple and expensive inequities. We can’t let those who want to protect the privileged get away with insisting that we do nothing until we can do everything.”