Last week Warren Buffett released information from his own tax return to help build his case that the ultrarich often pay taxes at a lower rate than those who earn far less. The Berkshire Hathaway chairman said his 2010 tax return included $62.9 million of adjusted gross income (AGI) and $39.8 million of taxable income. He said he paid tax of $6.9 million, for a federal tax rate of 17.3%.

By contrast, he said, many workers in his office pay taxes at rates "in the 30s" when both wages and all payroll taxes are taken into account.

...