For households earning between $70,000 and $120,000, the average savings would be about $2,000. Those making between $40,000 and $70,000 would save about $800. The bottom 20 percent – those making less than $20,000 – would see their average federal tax rate increase $149.

Comparing the two candidates on income taxes carries a giant asterisk.

Romney pledges to make his plan “revenue neutral” and says the wealthy would continue the same share of the government’s total tax collection. But he’s refused to identify which tax breaks he’d target to balance the books, and experts with the Tax Policy Center said that makes a side-by-side comparison impossible.

The center said there aren’t enough tax breaks for the wealthy for Romney to target and that he’d be unable to keep his promise to keep his plan revenue neutral without eliminating tax breaks for the 95 percent of households with incomes under $200,000.

“The details are so sparse, it is impossible to figure out whether they can achieve their goals, especially Romney,” said David Kautter, managing director of the Kogod Tax Center at American University.

Romney’s campaign rejects the policy center’s report, and Romney during last week’s presidential debate insisted that he wouldn’t raise taxes on the middle class or grow the deficit.

Before the debate, Romney floated the idea of a cap on income tax deductions to pay for lost revenues. The principle is something Obama has also entertained, but there has been little interest on Capitol Hill, analysts say. In an interview with a Denver TV station, Romney suggested up to a $17,000 limit for families, though his campaign says he’s not necessarily endorsing the approach.

CORPORATE TAXES

Romney would repeal the corporate alternative minimum tax, cut the corporate tax rate from 35 percent to 25 percent, make a research tax credit permanent and switch to a “territorial tax system,” so that profits earned abroad by U.S.-based multinationals would not be subject to U.S. taxes.

Obama would “go in the exact the opposition direction,” said Kautter, adding that Obama would try to expand the existing worldwide system of taxing U.S. corporations, provide incentives for them to move jobs back to the U.S. and penalize companies that try to move jobs offshore.

Obama would cut the corporate rate, though not as deeply. He’d cut it to 28 percent for some. For domestic manufacturers, he’d cut the tax rate to 25 percent.

Obama also would eliminate a number of oil and gas preferences in the tax law, along with reducing the depreciation for corporate aircraft.

ESTATE TAX

Under the temporary Bush-era tax cuts, estates worth less than $5 million – $10 million for couples – are exempt from the tax, which can take 35 percent for Uncle Sam.

On Jan. 1, however, the tax shoots back up to its old levels, hitting estates valued at $1 million or more and assessing a top rate of 55 percent.

Romney proposes to repeal the estate tax, which is paid by a small number of wealthy families.

Obama would split the difference. He’d exempt estates worth less than $3.5 million – $7 million for couples – and set the top tax rate at 45 percent – the same levels that were in effect in 2009.

The Tax Policy Center has concluded that for households earning between $70,000 and $120,000, Obama’s plan would pay about $71 more in taxes. Those making between $40,000 and $70,000 would save about $11.

The biggest earners would be hardest hit: Those making more than $600,000 would see about an increase of about $100,000, and those at the very top – making nearly $3 million – would see a $549,000 increase.

The bottom 20 percent – those making less than $20,000 – would see their average federal tax rate fall by $2.