Section 1.6109-1 - Identifying numbers(a)Information to be furnished after April 15, 1974. For provisions concerning the requesting and furnishing of identifying numbers with respect to returns, statements, and other documents which must be filed after April 15, 1974, see § 301.6109-1 of this chapter (Regulations on Procedure and Administration).(b)Information to be furnished before April 15, 1974. For provisions concerning the requesting and furnishing of identifying numbers with respect to returns, statements, and other documents which must be filed before April 16, 1974, see 26 CFR § 1.6109-1 (revised as of April 1, 1973).T.D. 7306, 39 FR 9946, Mar. 15, 1974; 39 FR 11080, Mar. 25, 1974