As most now know, extraordinary tax savings are taking place for U.S. persons dying in 2010, because of failure by Congress to update the estate tax. The most dramatic example to date is that of Dan L. Duncan, a Texas pipeline tycoon and fanatic big game hunter who died in March, leaving an estate and family businesses worth $9 billion.

Had Mr. Duncan died three months earlier, 45 percent of his estate would have been paid in tax. If he survived to 2011, the tax would increase to 55 percent. However, by dying in 2010, a loophole means Duncan’s family owes no estate tax at all!

The one-year gap was adopted in 2001 and it always was thought that Congress would act to plug it before the tax expired, but it did not. Estate tax only affects about 5,500 estates per year and in fact generates a relatively small portion of government revenues, but there is a political dimension to allowing a loophole for the ultrarich in an economic downturn.

While Japan handles taxes a different way, taxing donees rather than the estate, and there are various exemptions, there is obviously now a dramatic difference in tax levels that makes wise and flexible estate planning all the more significant. See article