is not prevented on September 26, 1961, by the operation of any law or rule of law. The election is also effective for any taxable year beginning before January 1, 1961, in respect of which an assessment of a deficiency has been made but not collected on or before September 26, 1961.
26 C.F.R. §1.9004-1
75 Stat. 674; 26 U.S.C. 613 note