The Form 706 is the return used to file the tax return on the transfer of assets held by the estate. (THIS IS DIFFERNT THAN THE FORM 1041 THAT REPORTS THE INCOME EARNED BY THE ESTATE PRIOR TO DISTRIBUTION TO BENEFICIARIES).  This retrun is due 9 months after the death of the decedent.  Without proper planning this could force a quick sale of the assets at below their value to have the money available to pay the estate tax. The current requirement is to file an estate tax return for estates valued at over $5 million, but this value will likely be lowered.  In some cases estates with lower values should still prepare and file the tax return in case there is ever a question on the value placed on the estate.