Sec. 613.Percentage Depletion. * * *
is not prevented on September 14, 1960, by the operation of any law or rule of law. The election also applies to taxable years beginning before January 1, 1961, in respect of which an assessment of a deficiency has been made but not collected on or before September 14, 1960.
26 C.F.R. §1.9003-1