Just before senators departed for the Christmas holiday, they wrapped up most of their pressing business for the year, including health care reform and an extension of the debt ceiling, but they failed to address the expiring estate tax. Because of the Senate's inaction, the estate tax effectively died on Jan. 1 and will stay dead until Jan. 1, 2011. That is until senators return from their winter break and resurrect the tax, which top tax writers on Capitol Hill are promising to do before March.