As the mainstream Republican establishment begins to coalesce around Mitt Romney following his caucus victory in Iowa, the former Massachusetts governor should also come under increased scrutiny for his hardline conservative positions on tax policy, which many Americans rightly perceive as out of touch with both fiscal reality and growing economic inequality. Romney’s stated opposition to any new income taxes and his promise to lower capital gains tax rates and eliminate the estate tax look particularly out of touch in light of a new report from the Congressional Research Service, which concludes that capital gains—the primary source of income for Mitt Romney and others in the top 1 percent—are now the single greatest driver of income inequality today.

According to the report, GDP grew a healthy 38 percent in the decade between 1996 and 2006 (the last year before the boom-bust cycle of 2007-2008), with average inflation-adjusted after-tax income increasing about 25 percent. But that average conceals an astounding divergence in outcomes between the nation's richest and poorest citizens: while income of the wealtheist 1 percent nearly doubled, the bottom 20 percent actually saw their income decrease by 6 percent. And because the CRS analysis only used data from active tax filers, those numbers may even underestimate the true width of the income gap.

Growth in real after tax income by group 96-06

The CRS data confirms earlier reports from the likes of the Congressional Budget Office that suggest that the tax code has become less progressive over time, decreasing inequality by less than 4 percent in 2006. Still, the inequality encouraged by the Bush tax cuts—which provided enormous savings at the top of the income distribution—pales in comparison to the incredible shift from labor income to capital income among the wealthiest 5 percent, which, Jared Bernstein muses, “seems endemic of a society that devalues work while providing outsized rewards for speculation and asset accumulation.”

The graph below, culled from the CRS data, illustrates the growing rift between the top 1 percent—who now take the majority of their income from cheaply taxed capital gains and dividends—and the bottom 99 percent, who continue to derive nearly all of their income from wages. It is a troubling paradigm shift in the way our society values labor and rewards risk-taking, but perhaps a natural evolution for the “you're on your own” culture of today's Republican party.

For more, check out Greg Anrig's 10 Reasons to Eliminate the Tax Break for Capital Gains.

Sources of Income by Income Group Wage vs Capital Gains 1996-2006