20 C.F.R. § 235.1
Effective January 1, 1975, the Railroad Retirement Act of 1974 (Act) requires the Railroad Retirement Board (Board) to provide for the payment of monthly social security benefit payments on behalf of the Social Security Administration to certain individuals as described in § 235.3 of this part. However, any such individual who was receiving benefits from the Social Security Administration prior to January 1, 1975, will continue to receive benefits from that agency unless he or she becomes eligible for a different type of social security benefit after that date and files a new application with the Social Security Administration for that benefit. Benefits under the new entitlement will be paid by the Board. The Act provides an offset in the railroad retirement benefits of individuals who are also eligible for social security benefits. Because the Board is required to make this offset, the payment of social security benefits by the Board is authorized for the purpose of convenience in the administration of the Act.
20 C.F.R. §235.1