Mr. Shapiro said the figures added to the center's "concerns over the increasingly regressive effects" of the reduced tax rates on capital.

Combined with the mortgage interest deduction and the regressive effects of state taxation, it produces closer to a flat-tax effect.

IRL claim that in the rush to introduce revenue raising measures the regressive effects of a carbon tax will not be adequately offset.

An increase in the personal exemption for income taxes -or better, an increase in the earned income tax credit - would offset any regressive effects of the gas tax increase.

Tax systems could utilize a flat sales tax to target all consumption, which can be modified with rebates or exemptions to remove regressive effects (such as the proposed FairTax in the U.S.).