One of the apparent hold-ups in the Senate negotiations on the "fiscal cliff" is a dispute over the estate tax.

Americans pay the estate tax when they inherit money or property
beyond a certain threshold. According to a 2010 law, the estate tax currently exempts the first $5 million of inheritance and taxes the remainder at 35 percent.

Republicans want to preserve this arrangement, but Obama wants to make it less generous, reducing the exemption to $3.5 million and taxing the remainder at a 45 percent rate.