The total number of filed estate tax returns fell from just about 108,000 in 2001 to 45,000 in 2005, according to the Summer 2007 IRS Statistics of Income.  By the same token, the total amount of assets encompassed by those returns fell only 14% during the same time period, from $216 billion in 2001 to $185 billion in 2005.  According to tax attorney Charles Rubin (Boca Raton, FL), the reduction in returns is due to the “steady increase in the unified credit equivalent amount allowed for federal estate taxes,” which rose from $600,000 in 2001 to $1.5 million for decedents in 2005.  “Since estates with less than the available credit equivalent in assets do not need to file, increases in the credit result in [fewer] returns.”  The current credit equivalent amount is $2 million, suggesting the declining trend in estate tax returns will continue.