Though only 4.4% of households actually have financial assets greater than $1 million, the LIMRA report found that many more would be affected because estate tax calculations include other assets like real estate, life insurance and privately held business interests.
Looking at data from the Federal Reserve Board's Survey of Consumer Finances, LIMRA analyzed three scenarios that Congress will likely consider.
Congress could let the current law expire, extend the current law or enact a compromise between the two.
If Congress does not act, the law will expire and revert back to the $1 million exemption and 55% minimum tax. This outcome would result in 14.7 households, almost 12.5%, receiving an average potential tax liability of $1.4 million, according to the report.
If the current law is extended, with a $5 million exemption and 35% minimum tax, only 2.4 U.S. households, just over 2%, will be affected by the law. Their potential tax liability would average $3.1 million.
And finally if instead congress reaches a compromise, of a $3.5 million exemption and 45% minimum tax, 3.6 million families, or just above 3%, could see a tax bill of about $2.6 million each on average.
While life insurance can help households pay for a decedent's estate tax, most families still won't have enough to cover the tax, according to LIMRA's analysis.
Under the first scenario, if the law expires, 55% of families with a potential tax liability wouldn't have enough. Under the compromise scenario, 53% wouldn't have enough.
"The uncertainty that has surrounded our estate tax laws has made it impossible for Americans to plan for a reasonable transition of their assets to the ones they love and to charity for the greater good," Robert Kerzner, president and CEO of LIMRA, said in a statement.