Do the rich get richer because of tax breaks?

Senate Budget Committee Chairman Kent Conrad thinks so. The North Dakota Democrat made a big pitch for getting rid of many tax deductions and credits at a hearing on Wednesday, saying they’re contributing to a wide disparity in income between the wealthy and not-so-wealthy.

Sen. Kent Conrad (D., N.D.) (AP Photo/Alex Brandon, File)

Citing recent research by tax expert Martin Sullivan, Mr. Conrad said a resident of a typical Park Avenue building in New York – with average household income of $1.1 million – is paying taxes at an effective rate of about 15%. But the rate for janitors in the building hovers closer to 25%, Mr. Conrad said. “I don’t know how anybody can defend or justify that kind of tax burden,” Mr. Conrad said.

The discrepancy has been noted previously, for example by investor Warren Buffett, who often complains that his tax rate is lower than his secretary’s. The differential is largely due to the lower tax rates the government imposes on investment income, such as capital gains and dividends. Defenders of the policy say it promotes investment and thus economic efficiency to keep taxes low on capital…