28 CFR 513.31 - Limitations.
(a) Social Security Numbers. As of September 27, 1975, Social Security Numbers may not be used in their entirety as a method of identification for any Bureau record system, unless such use is authorized by statute or by regulation adopted prior to January 1, 1975.
Title 28 published on 2013-07-01
no entries appear in the Federal Register after this date.