The deceased individual's personal representative is either the executor or administrator of the estate. An executor is an individual named in the will, while an administrator is an individual the court appoints when the will doesn't name an executor or the executor named in the will isn't able to serve. The personal representative must file Form 56 with the IRS to inform it of his responsibility for the deceased individual's final affairs.
Filing the Return
If you are serving as the personal representative for a deceased individual, you must sign his final tax return. You must also write "deceased" next to the individual's name and include the date of death on the top of the return. If you are filing the final return jointly with the individual's surviving spouse, she must also sign the return. The deceased person's final tax return is due at the same time that it would have been due if the individual hadn't died.
You shouldn't attach the death certificate or any other proof of death to the deceased individual's final tax return. However, you must keep a copy of the death certificate in your records in case the IRS requests it later. You must also attach a copy of the court order that names you as legal representative of the estate to the tax return.
No Personal Representative
If no personal representative for the estate exists, the surviving spouse can file a joint return on behalf of the deceased individual. If no personal representative or surviving spouse exists, the individual in charge of the deceased person's property can file the return. In either of these cases, it isn't necessary to submit a copy of the death certificate unless the IRS specifically requests it.