The federal tax on transfers of wealth from estates has been with us since the passage of the Revenue Act of 1916, although there were similar temporary levies around the time of the Spanish-American War. This tax came to an end, albeit temporarily, on December 31, 2009.

How did this happen? In 2001, Congress passed legislation gradually raising exemptions and reducing tax rates, resulting in a 2009 estate exemption of $3.5 million and a 45% estate-tax rate on amounts over the exemption.

The plan called for a “sunset” of the estate tax in 2010, followed by a “sunrise” in 2011 of a 55% estate-tax rate and $1 million exemption. On top of this, the generation-skipping tax on transfers has lapsed completely.

Many observers were certain that before the end of 2009, Congress would either set up a new rate and exemption scheme, or just vote to continue the current 45%/$3.5 million structure for an additional year. They didn’t do either.

There are discussions about passing a retroactive provision to cover at least 2010, but the path is not yet clear. Leaving aside the often vitriolic discussion of the impact of the estate tax—or any tax—there’s no question that, with the estate-tax sunset, uncertainty reigns.

The net effect is that there could be some nasty surprises in store for some taxpayers at a time when they’re already grieving for loved ones, though there could be windfalls as well. This probably will all get straightened out soon … but, again, that was the sentiment last year.

What should you do? Thoughtful, deliberate actions are preferable to snap decisions. If you’re concerned, call your tax and legal advisors for guidance. They may say all you can do is wait.