* Romney tax plan cuts 20 percent for all income groups
* Those making over $1 million benefit most under plan
* Romney hasn't spelled out how to fund tax cuts
By Kim Dixon
WASHINGTON, Aug 1 (Reuters) - Republican U.S. presidential challenger Mitt Romney's proposal to slash individual income taxes by 20 percent across-the-board would primarily boost the income of the wealthiest taxpayers, according to a nonpartisan analysis released on Wednesday.
The report by the centrist Tax Policy Center found that Romney's tax cuts would boost after-tax income by an average of 4.1 percent for those earning more than $1 million a year, while reducing by an average of 1.2 percent the after-tax income of individuals earning less than $200,000.
Tax policy and how to tame the U.S. government's budget deficit, topping $1 trillion in recent years, is a major point of contrast in the presidential race, in which Romney will face President Barack Obama on Nov. 6.
Romney, a multi-millionaire who made his fortune at private equity firm Bain Capital, has not spelled out how he would lower marginal tax rates. But he has said broadly he would cut some tax benefits for the wealthy.
Because the value of the 20 percent tax cut for richer Americans would exceed the gains they get from popular tax breaks that Romney would chop, they would see the greatest income gain from Romney's possible changes, the study said.
"We add up how much people get from the tax cuts and then add up how much can be potentially be raised," from ending tax breaks, said Adam Looney, an economist and one of the study's authors.
About two-thirds of the $1.1 trillion in revenues that the government foregoes annually because of tax breaks would have to be curbed to fund Romney's tax cut, the analysts said.
These tax breaks include popular ones such as the mortgage interest deduction, the break for employer-provided health insurance, and credits for low- and middle-income families.
The analysis assumed elimination of tax breaks would start with the wealthy as Romney has suggested, and it assumed some revenue growth from lower tax rates, a hallmark of Republican tax policy.
Obama has blasted Romney's tax plan for disproportionately benefiting the wealthy.
The tax policy debate is expected to intensify at the end of 2012, with the expiration of lower tax rates for all Americans enacted under Republican President George W. Bush.
The Democratic-led Senate last week passed legislation extending most of those tax rates - but not for households earning more than $250,000 a year.
The Republican-led House of Representatives will likely pass their plan to extend the current rates some time this week.
The dispute is not likely to be resolved until after the elections.
Romney spokeswoman Amanda Henneberg said she could not respond to the center's report without reading it first.
Romney's tax proposal also includes cutting some taxes on investment income and eliminating taxes on estates passed on to heirs. (Reporting by Kim Dixon; Editing by Kevin Drawbaugh and Lisa Shumaker)
Copyright 2012 Thomson Reuters. Click for Restrictions.
With A Little Help From My Friends (Joe Cocker)
<strong><a href="http://www.huffingtonpost.com/2012/05/28/mitt-romney-will-not-repu_n_1551540.html" target="_hplink">(May 28, 2012) --</a></strong> Despite a resurgence of <a href="http://www.thedailybeast.com/articles/2012/05/25/mitt-romney-s-new-bff-donald-trump.html" target="_hplink">Donald Trump's birther claims</a>, Romney refused to repudiate the billionaire, who has been helping with his 2012 campaign efforts. "You know, I don't agree with all the people who support me ... I need to get 50.1 percent or more and I'm appreciative to have the help of a lot of good people," Romney said. (Photo by Ethan Miller/Getty Images)
Who Let The Dogs Out (Baha Men)
<strong><a href="http://www.huffingtonpost.com/2012/04/16/mitt-romney-seamus_n_1429925.html" target="_hplink">(April 16, 2012) -- </a></strong> In an interview with ABC's Diane Sawyer, Romney discussed the political fallout over strapping his dog Seamus to a car roof. He admits that he probably would not do it again. (Handout)
It's The End Of The World As We Know It (R.E.M.)
<strong><a href="http://www.huffingtonpost.com/2012/04/04/mitt-romney-medicare-president-obama_n_1403267.html" target="_hplink">WASHINGTON, D.C. (April 4, 2012) --</a></strong> Speaking before the Newspaper Association of America, Romney attacked Barack Obama on his health record, claiming the president "has taken a series of steps that end Medicare as we know it." (Photo: Jim Watson/AFP/Getty Images)
For The Love Of Money (The O'Jays)
<a href="http://www.huffingtonpost.com/2012/03/14/mitt-romney-i-made-a-lot-of-money_n_1345516.html" target="_hplink"><strong>NEW YORK, N.Y. (March 14, 2012) -- </strong></a> Romney became testy on Fox News while discussing his appeal to lower-income voters. On the same day, Occupy Wall Street protesters staged a demonstration outside Mitt's Waldorf Astoria hotel fundraiser. (Photo: Emmanuel Dunand/AFP/Getty Images)
People Are Strange (The Doors)
<strong><a href="http://www.huffingtonpost.com/2012/03/09/mitt-romney-south_n_1334478.html" target="_hplink">PASCAGOULA, Miss. (March 9, 2012) --</a></strong> While on the trail in Alabama and Mississippi, Romney got in touch with his Southern side, learning how to say "y'all" and liking his grits. With those new experiences in hand, he admitted that "strange things are happening to me." (Photo: AP/Evan Vucci)
Pink Cadillac (Bruce Springsteen)
<a href="http://www.huffingtonpost.com/2012/02/24/mitt-romney-cadillac_n_1299740.html" target="_hplink"><strong>DETROIT, Mich. (Feb. 24, 2012) -- </strong></a> While speaking before the Detroit Economic Club at Ford Field, Romney listed not two, not three, but four American-made cars that he and his wife, Ann, owned. Among the vehicles: "a couple of Cadillacs." (Photo: Scott Olson/Getty Images)
It's The Hard-Knock Life (Annie & The Orphans)
<strong><a href="http://www.huffingtonpost.com/2012/02/01/mitt-romney-very-poor_n_1246557.html" target="_hplink">TAMPA, Fla. (Feb. 1, 2012) --</a></strong> In an interview with CNN, Romney noted that he is "not concerned about the very poor," citing the social safety net for that segment of the populace. (Photo: Ethan Miller/Getty Images)
America The Beautiful
<a href="http://www.huffingtonpost.com/2012/01/31/mitt-romney-america-the-beautiful-_n_1243908.html" target="_hplink"><strong>THE VILLAGES, Fla. (Jan. 31, 2012) --</strong></a> On the eve of Florida's primary, Romney led his supporters in a singing of the patriotic song. (Photo: Emmanuel Dunand/AFP/Getty Images)
Successful (Drake, Lil Wayne)
<a href="http://www.huffingtonpost.com/2012/01/19/mitt-romney-tax-returns_n_1217708.html" target="_hplink"> <strong>CHARLESTON, S.C. (Jan. 19, 2012) -- </strong></a> During CNN's GOP debate, Romney refused to commit to disclosing his tax returns, offering no apologies for his success. (Photo: Emmanuel Dunand/AFP/Getty Images)
Bye Bye Bye ('N Sync)
<a href="http://www.huffingtonpost.com/2012/01/09/mitt-romney-i-like-being-able-to-fire-people_n_1194115.html" target="_hplink"><strong>NASHUA, N.H. (Jan. 9, 2012) -- </strong></a> In a speech about insurance options, Romney tells audience members, "I like being able to fire people who provide services to me." (Photo:AP/Charles Dharapak)
Don't Know Why (Norah Jones)
<strong><a href="http://www.huffingtonpost.com/2011/10/28/mitt-romney-embraces-climate-change-denial_n_1063905.html" target="_hplink">PITTSBURGH, Pa. (Oct. 27, 2011) --</a></strong> Back in June 2011, Romney said humans are somewhat tied to climate change. By October, he had reversed course, saying "We don't know what causes climate change." (Photo: Jim Watson/AFP/Getty Images)