20 CFR 202.14 : Employees' Benefits (§ 1.1 To Parts 1011-1099) — (§ 1.1 To Parts 376-399) — Railroad Retirement Board (§ 200.1 To Parts 376-399) — Regulations Under The Railroad Retirement Act (§ 201.1 To § 295.7) — Employers Under The Act (§ 202.1 To § 202.15) — Service incidental to railroad transportation.

An organization, association, bureau or agency is performing a service in connection with or incidental to railroad transportation whenever it is engaged in the performance of functions which would normally be performed by the constituent employers in the absence of such organization, association, bureau, or agency.