How long after my spouse's and my death does my family have to pay my federal estate tax liability?

The federal estate tax return, Form 706, must be filed within 9 months after a decedent's death. The tax is due with the return. The responsibility of filing the return normally rests with the personal representative or executor of the decedent's estate. The Internal Revenue Code imposes a penalty of 5 percent of the amount of the tax for each month of delinquency (with a maximum of 25 percent), unless the person responsible for filing the return can show that the delay was due to reasonable cause and not due to willful neglect. Upon a showing of good and sufficient cause, an extension, usually limited to 6 months, can be obtained for filing the return.