14 CFR 1212.604 - Social security numbers.
(a) It is unlawful for NASA to deny to individuals any rights, benefits, or privileges provided by law because of the individuals' refusal to disclose their social security numbers, except where:
(1) The disclosure is required by law; or
(2) The disclosure is from a system of records in existence and operating before January 1, 1975, and was required under statute or regulation adopted before that date to verify the identity of the individual(s).
(b) Any time individuals are requested to disclose their social security numbers, NASA shall indicate whether that disclosure is mandatory or voluntary, by what authority the numbers are requested, and what uses will be made of them.