FACTBOX: Leading candidates' positions on taxes

(Reuters) - Following are the leading 2008 U.S. presidential candidates' positions on taxes:

REPUBLICANS:

Arizona Sen. John McCain

Make permanent the tax cuts adopted during Bush administration that are set to expire in 2010. Have three-fifths majority in Congress required to approve tax increases. Advocates repealing Alternative Minimum Tax, creating tax credits for health, education and those with children.

Former Massachusetts Gov. Mitt Romney

Make permanent the tax cuts adopted during Bush administration. Eliminate taxes on dividends, capital gains and interest for middle-class families. Individuals who make less than $200,000 would not pay taxes on any savings income. Eliminate inheritance tax, reduce corporate tax rates and oppose raising Social Security taxes.

Former Arkansas Gov. Mike Huckabee

Advocates eliminating all income and payroll taxes and replacing those with a consumption tax on all new goods. Would abolish the Internal Revenue Service and offer a monthly rebate for those below the poverty line. Critics argue the tax would have to be high and could lead people to try circumvent the system by doing transactions under the table.

Former New York Mayor Rudy Giuliani

Make permanent income tax cuts adopted during Bush administration and cut the corporate tax rate to 25 percent from 35 percent. Give taxpayers the option of choosing a simplified tax form with three brackets - 10 percent, 15 percent and 30 percent. Tie the so-called Alternative Minimum Tax, a 40-year-old tax meant for the super-wealthy, to inflation to avoid it affecting almost 20 percent of taxpayers. Eliminate inheritance tax.

Former Tennessee Sen. Fred Thompson

Lower taxes such as corporate rates which he said would spur the economy and generate more tax revenue, and make permanent Bush administration tax cuts. End estate tax and give taxpayers option of sticking with traditional tax code with its credits and deductions or opt for a flat tax with two rates, 10 percent for incomes up to $100,000 and 25 percent over that amount.

DEMOCRATS:

New York Sen. Hillary Clinton

Repeal Bush administration tax cuts for those making $250,000 or more annually. Make permanent tax relief for married couples that was part of Bush plan against "marriage tax." Offer college tuition tax deduction and credits for children and adoption. Has encouraged wage credits for businesses to boost job creation. Raise tax rate on "carried interest" gains made by senior partners in the private equity and hedge fund businesses.

Illinois Sen. Barack Obama