WASHINGTON - Republican presidential candidate Mitt Romney and his wife, Ann, gave about 30 percent of their $13.7 million in 2011 income to charity, but did not take the full write-off, making their effective tax rate higher.

The move, which was contained in Romney's 2011 tax return released on Friday, was described by tax experts as unusual and by the top Senate Democrat as manipulation of the tax code.

"I was in private practice for 40 years and don't know that I ever had a client who said, 'I don't want to take all my deductions,'" said David Kautter of American University's Kogod Tax Center, who spent his career at accounting giant Ernst & Young.

Kautter estimated that if Romney had taken the full charitable tax break, his effective tax rate would have been about 10.5 percent. The return showed Romney paid an effective rate of 14.1 percent last year.

During a Republican presidential debate in January, Romney said, "I don't think you want someone as the candidate for president who pays more taxes than he owes."

The Romneys reported about $4 million in charitable donations, including at least $1.1 million given to the Mormon Church to which they belong. Mormons typically "tithe" 10 percent of their income to the church.

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