Notwithstanding the provisions of Sec. 20.6091-1 the Commissioner may permit the filing of the preliminary notice required by Sec. 20.6036-1 and the estate tax return required by Sec. 20.6018-1 in any local Internal Revenue Service office. [T.D. 6600, 27 FR 4986, May 29, 1962, as amended by T.D. 9156, 69 FR 55745, Sept. 16, 2004]