The personal representative of every estate subject to the tax imposed by the Estate Tax Act [7-7-1 to 7-7-12 NMSA 1978] who is required by the laws of the United States to file a federal estate tax return shall file with the department on or before the date the federal estate tax return is required to be filed, including any extension of time for filing the federal estate tax return:
NMS § 7-7-5