"The empty nesters who don't have a mortgage any more, they're in a very different situation than the 30-somethings with three kids, who are trying to save for retirement, trying to pay off a mortgage, trying to save for their kids' education," he said.

The sample upper-income family paid $12,000 in mortgage interest, had $10,000 in charitable contributions and paid $29,000 in state and local taxes.

Expiring Tax Cuts

If Congress extends the expiring tax cuts, this family would pay $25,443 in federal income taxes. That tax burden plummets under the Cain and Huntsman plans that offer lower marginal rates and exempt investment income. In Huntsman's proposal, this family would receive a 40.8 percent tax cut and pay $15,064 in federal taxes, even without itemized deductions.

Romney's plan to exempt investment income from capital gains taxes for families with adjusted gross income of less than $200,000 would lead to a tax cut for this family of $8,920, or 35 percent.

If the value of the business grows over the next few decades, the owners would benefit from most of the candidates' plans to repeal the estate tax. Ron Paul, for example, proposes ending the estate tax and eliminating taxes on savings.

Middle-income Family

Unlike the upper-income and wealthy families, the sample middle-income family can't take full advantage of the tax code's incentives for retirement savings because it spends a greater percentage of its income each year.

This family earns $100,000, puts $2,000 aside in an individual retirement account and receives $2,000 in capital gains. Like most U.S. households, it takes the standard deduction, because its mortgage interest, charitable contributions and state and local taxes total $10,000, below the current standard deduction of $11,600 for married couples.

The tax code's benefits to this family are credits for child care and education, and the candidates' plans that limit or end these benefits tend to increase this household's tax liability.

"One of these things that these proposals are doing is playing off the prominence of the top rate and sort of taking people's eyes of the ball, which is how much tax you pay," said Lawrence Zelenak, a tax law professor at Duke University in Durham, North Carolina.

If current tax policy were extended, the middle-income family would pay $6,535 in federal income taxes.