If all scheduled tax increases take place as scheduled in 2013, they will generate $536 billion of revenue in 2013. The increase could net $5 trillion over ten years, the Tax Policy Center states.
"No single policy is enough on its own, but as part of the overall package, it's significant," said Rosenberg. "But perhaps more importantly is who's being affected to the extent that we care about not only the revenue but distribution of taxes."
The change in taxation of capital gains and dividends "overwhelmingly" affects the top of the income distribution. Specifically, if the Bush tax cuts for high-income earners from 2003 for capital gains and dividends expire, then only 1 percent of taxpayers would be affected, all in the top income quintile, according to the center.
Kelly Erb, a tax attorney, said many middle-income taxpayers often carry most of their financial assets, outside of their homes, in mutual funds or retirement accounts such as 401(k)s. Those are often tax-deferred financial vehicles from which account holders withdraw money at retirement age. At that point, they are usually taxed as ordinary income.
For individuals who have stock holdings this year, Erb said most individuals should not necessarily sell their appreciated stock holdings in anticipation of the increase in capital gains and dividends tax rates.
"I don't think you should change your behavior," she said. "I think you should look at the timing of your behavior."
Because the capital gains tax rate applies to assets that have appreciated in price, some investors may benefit from waiting until the New Year if a stock's price is decreasing but hasn't yet led to a net capital loss.
"You may have the opportunity to offset capital losses at a higher rate," she said.
On the other hand, if an investor was planning to sell an asset anyway, it helps to talk with a financial professional or broker about how it has affected your portfolio.
"By December, you know what your gains are for the year usually. That's why they say to get rid of underperformers then," she said.
Erb said the uncertainty for regarding the tax rates is unfair to taxpayers, but particularly to low and middle-income taxpayers who can't afford to pay for professional advice to strategize their financial plans.
Dozens of companies have announced special dividends to shareholders late this year, including Costco Wholesale Corp., to avoid anticipated tax increases.
"I think it's impossible to plan," Erb said for most individuals. "I think people should be angry at Congress for putting us in this predicament."