For disallowance of certain charitable, etc., deductions otherwise allowable under section 642(c), see sections 508(d) and 4948(c)(4). See also 26 CFR 1.681(b) - 1 and 1.681(c) - 1 (rev. as of Apr. 1, 1974) for provisions applying before January 1, 1970.
26 C.F.R. §1.681(b)-1