Last January, Congress passed what was considered to be a permanent 40 percent rate for the estate tax and a $5.25 million asset exemption per individual.

The exemption is indexed to inflation in future years. But now several lawmakers have reintroduced legislation that would repeal the estate tax altogether.

Senator John Thune, R-S.D., one of the key proponents of the effort, says the bill would result in about $20 billion in lost revenue, but that the measure would stimulate more economic growth and jobs.

Many agriculture groups are in favor of getting rid of the tax, but passage is unlikely at a time when the main focus is reducing the federal deficit.