The media tends to place a great deal of focus on federal income tax, but despite that, the number of estates that actually pay this federal tax are proportionately small. Less than 12,000 estate tax returns were filed with the IRS in 2014, and of those, most of the estates did not even have to pay any federal estate taxes.
Thus, the estates that do pay the tax are those of the wealthiest of the wealthy in the country. By looking at the data on the returns where an estate tax was due it is possible to get an idea of what kind of assets wealthy people have.
As reported by the Wall Street Journal, in "When the Superrich Die, Here's What's in Their Wallets," the IRS has recently released that information for estate tax returns filed in 2014.