For another, the tax take tends to rise during periods of fast economic growth, despite constant tax rates.

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To folks like Bernie Sanders, the question of tax incidence seems to boil down to a question of multiplication: assume that incomes will remain constant as the tax rates increase, then just give the government its extra 5% or 10%.

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With 2011 and 2012 income tax rates constant, the old-fashioned advice to accelerate deductions into the current tax year and defer income until the following year should apply this December, says Mel Schwarz, director of tax legislative affairs at Grant Thornton in Washington.

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