But if the estate-tax provisions are allowed to expire, there will be a 60 percent drop in the exemption and a 20 percent gross increase in the tax rate.

The estate-tax provisions of the Bush tax cuts, as amended in late 2010 for 2011 and 2012, establish a $5 million exemption and a maximum 35 percent tax rate.

If the tax cuts are allowed to expire, the estate tax will spring back to 2001 levels, with a $1 million personal exemption and a 55 percent top tax rate.

“When compared to the changes in rates that will occur, both the percentage of change and the gross percentage increase are dramatically more than virtually every other change,” Katzenstein said.

And then there is the uncertainty. Doug Siegler, a partner at Sutherland Asbill & Brennan inWashington, and a member of Sutherland's Tax Practice Group, says a Democratic proposal introduced this week that has a fair chance of passage by the end of the year, would return estate tax policy to 2009 levels.

The bill, S. 3393, would establish a $3.5 million per person exemption, indexed for inflation, and a 45 percent top rate.

Siegler says the thinking of most tax practitioners is that once the election is over, the most likely options are that Congress will decide to retain either the current system, or to return to the 2009 levels.

Symington explains that most agencies and brokerages are small businesses, organized as pass-through entities such as S-Corporations, Partnerships and Sole Proprietorships.

That means they pay taxes at individual rates, he said. “In addition, many of our small business members are family-owned,” he adds.

He says allowing current estate-tax law to expire would mean that in many cases a family business would have to be liquidated in order to pay the government.

“This translates to lost jobs in a time when our economy can least afford it,” Symington says.