20 C.F.R. § 235.3
Who is paid social security benefits by the Board
The following individuals, if entitled to social security benefits, are paid such benefits by the Board:
(a) A railroad employee who has been credited with at least 120 months of railroad service (or at least 60 months of railroad service, all of which accrue after December 31, 1995);
(b) A wife or husband of a railroad employee who has been credited with at least 120 months of railroad service (or at least 60 months of railroad service, all of which accrue after December 31, 1995);
(c) A divorced wife or husband of a railroad employee who has been credited with at least 120 months of railroad service (or at least 60 months of railroad service, all of which accrue after December 31, 1995);
(d) A survivor of a railroad employee, including a surviving divorced spouse, remarried widow(er), surviving divorced mother or father, who is entitled, or upon application would be entitled, to an annuity under the Railroad Retirement Act; and
(e) Any other person entitled to benefits under title II of the Social Security Act based on the social security wages of a railroad employee who has been credited with at least 120 months of railroad service (or at least 60 months of railroad service, all of which accrue after December 31, 1995), except survivors of a railroad employee when the Social Security Administration has jurisdiction for survivor benefits. See part 221 of this chapter.