“The vast majority of small businesses will be unaffected,” said William G. Gale, an analyst at the Brookings Institution.
He said most of the people potentially hit by the tax increase don’t earn the majority of their income through their businesses. These top earners typically have many other sources of income, including salaries, bonuses, stock grants, capital gains and dividends.
“If the objective is to help small businesses, continuing the Bush tax cuts on high-income taxpayers isn’t the way to go,” Mr. Gale said. “It would miss more than 98 percent of small-business owners and would primarily help people who don’t make most of their money off those businesses.”
John Kartch, an analyst at Americans for Tax Reform, said the way businesses are organized seems to make a difference. The smallest businesses usually are organized as “sole proprietors,” have lower incomes and would not be affected as much by the rate increases.
But a vital sector of somewhat larger businesses organized as partnerships and “S chapter” corporations under the tax law would be hit hard, he said. These businesses, which include law firms and venture capital firms, also report their income as personal income on their tax returns and are subject to the highest rates.
The number of partnerships and S corporations has been growing, according to the Internal Revenue Service, because businesses see it as a good way to avoid double taxation of their income or profits. That may explain why many larger companies are now found in what once was mostly a “small-business” category of the tax code.
Citing IRS figures, Mr. Kartch said that virtually all of the profits of some 8 million partnerships and S corporations would be taxed at the higher rates under Mr. Obama’s plan.
He said doctors’ and dentists’ offices are examples of the kinds of businesses that would suffer the most.
“These are real small businesses,” Mr. Kartch said. “Raising taxes on these most successful of small businesses will cost jobs.”
While arcane facts about small businesses are bandied about, sentiment inside and outside Congress seems to be getting stronger for maintaining all the tax cuts, if only as a precaution to avoid damaging the increasingly fragile economic recovery and employment market. Employers have only tentatively begun to add jobs this year.
Economists in general favor at least a temporary extension of all the cuts so as not to disrupt the economy. Prompting concern was a recent Labor Department survey that found that businesses with fewer than 50 employees — which normally create as much as 75 percent of all jobs — accounted for 62 percent of all job cuts and only 54 percent of new jobs at the end of last year.
In light of the deteriorating job situation, a survey by the National Association of Business Economists found that 54 percent of economists support extending all the tax cuts.
Another 33 percent say Congress should follow the president’s plan and extend only those for the middle class. These economists also largely support extending the dividend and capital gains tax cuts that expire at the end of the year.
“The tax cut is important for small businesses,” said Sung Won Sohn, an economics professor at California State University at Channel Islands. “Many of them earn more than $250,000 and would be paying higher taxes if the cuts are allowed to expire. Often, they have significant dividend income.”
Just as important to encourage hiring, Mr. Sohn said, is for small businesses to have better access to bank loans, as maintained by the president.