Should well-off investors sell their money-making stocks this year to avoid paying higher taxes on their capital gains on a hunch that Democratic presidential candidate Sen. Barack Obama could win in November?

Right now, if an investor owns a stock for at least one year and one day, the maximum capital gains tax rate he or she would pay is 15 percent on the profits from a sale.

GOP candidate Sen. John McCain says he would keep the current top rate.

Obama would favor establishing a higher tax bracket for capital gains and qualified dividends for joint filers making more than $250,000. It would apply to singles making more than $200,000.

The latest reports indicate Obama’s proposal would put the top rate at 20 percent or close to it for long-term capital gains and qualified dividends. Obama also is proposing eliminating the capital gains taxes for small businesses and start-ups. There are no details yet on who would qualify, according to Roberton Williams, principal research associate for the Tax Policy Center, an independent think tank in Washington, D.C.

Fewer than one in seven individuals reported taxable capital gains in 2006, according to the Tax Policy Center.

More than half of the taxpayers with gains had incomes below $75,000. So, many retirees and lower-income taxpayers would not be hit with a higher rate.

Money withdrawn from a 401(k) plan is taxed at ordinary income tax rates.

A limited zero-percent capital gains tax rate is available from 2008 through 2010 as well. The rate applies to individuals in the 10 percent and 15 percent tax brackets. That group had paid 5 percent.

Going from a 15 percent top capital gains rate to a 20 percent rate might sound like small potatoes, particularly when investors would be thrilled to make money after the brutal action on Wall Street.

Yet, if an investor has a large dollar amount of capital gains, the higher rate could add up to a lot of money, according to Thomas Ochsenschlager, vice president of taxation of the American Institute of Certified Public Accountants.

For longer-term investors, a higher tax rate could mean an extra $1,000 in federal taxes, if you’re looking at $20,000 in capital gains.

Most capital gains are reported by high-income taxpayers. The Tax Policy Center noted that the 3 percent of returns with adjusted gross incomes of $200,000 or more in 2006 reported 83 percent of all capital gains that year.

The threat of higher cap gains rates is hanging over Wall Street.

“The longer the ambiguity, the longer it adds to the volatility in the market,” said Brian Belski, chief U.S. sector strategist for Merrill Lynch in New York.

Yet Belski said he would caution investors against making bold moves now. No one knows who will win or what kind of tax measure could pass. Yet, this issue is worth watching.

Mark Luscombe, principal analyst for CCH in Riverwoods, Ill., notes that new presidents tend to address their tax agendas in the first year in office.

Susan Tompor is the personal finance columnist for the Detroit Free Press. She can be reached at stompor@freepress.com.