social security number
(7) Social security number required No credit shall be allowed under this section to a taxpayer with respect to any qualifying child unless the taxpayer includes the social security number of such child on the return of tax for the taxable year. For purposes of the preceding sentence, the term “social security number” means a social security number issued to an individual by the Social Security Administration, but only if the social security number is issued— (A) to a citizen of the United States or pursuant to subclause (I) (or that portion of subclause (III) that relates to subclause (I)) of section 205(c)(2)(B)(i) of the Social Security Act, and (B) before the due date for such return.
26 USC § 24(h)(7)
None identified. Default scope is assumed to be the entire title.