45 U.S.C. § 231r

If title II of the Social Security Act [42 U.S.C. 401 et seq.] is amended at any time after December 31, 1974, to reduce the eligibility requirements for old-age insurance benefits, disability insurance benefits, wife’s insurance benefits payable to a wife, husband’s insurance benefits, child’s insurance benefits payable to a child of a deceased individual, widow’s insurance benefits payable to a widow, widower’s insurance benefits, mother’s insurance benefits payable to a widow, or parent’s insurance benefits, such reduced eligibility requirements shall be applicable, in accordance with regulations prescribed by the Board, to individuals, spouses, or survivors, as the case may be, under section 231a of this title to the extent that such reduced eligibility requirements would provide such individuals, spouses, or survivors with entitlement to annuities under such section 231a of this title to which they would not be entitled except for such reduced eligibility requirements: Provided, however, That no annuity shall be paid to any person pursuant to the provisions of this subsection if that person does not satisfy an eligibility requirement imposed by section 231a of this title of a kind not imposed by the Social Security Act [42 U.S.C. 301 et seq.] on December 31, 1974, or an eligibility requirement imposed by section 231a of this title of a kind which was imposed by the Social Security Act on December 31, 1974, but which was not reduced by the amendment to that Act: Provided further, That the annuity amounts to which such individuals, spouses, or survivors will be entitled under this subchapter by reason of the provisions of this subsection shall be only such amounts as are determined under the provisions of section 231b(a), 231c(a), or 231c(f), respectively, of this title.

If title II of the Social Security Act [42 U.S.C. 401 et seq.] is amended at any time after December 31, 1974, to provide monthly insurance benefits under that Act to a class of beneficiaries not entitled to such benefits thereunder prior to January 1, 1975, every person who is a member of such class of beneficiaries shall be entitled to annuities under section 231a of this title, in accordance with regulations prescribed by the Board, in an amount equal to the amount of the monthly insurance benefit to which such person would have been entitled under the Social Security Act [42 U.S.C. 301 et seq.] if service as an employee after December 31, 1936, had been included in the term “employment” as defined in that Act.

If section 226 [42 U.S.C. 426] or title XVIII [42 U.S.C. 1395 et seq.] of the Social Security Act is amended at any time after December 31, 1974, to reduce the conditions of entitlement to, or to expand the nature of, the benefits payable thereunder, or if health care benefits in addition to, or in lieu of, the benefits payable under such section 226 or such title XVIII are provided by any provision of law which becomes effective at any time after December 31, 1974, such reductions in the conditions of entitlement to benefits, such expanded benefits, or such additional, or substituted, health care benefits shall be available to every employee (as defined in this subchapter), and those deriving from him, in the same manner, and to the same extent, as if his service as an employee after December 31, 1936, had been included in the term “employment” as defined in the Social Security Act [42 U.S.C. 301 et seq.]. The Board shall have the same authority, in accordance with regulations prescribed by it, to determine the rights of employees who will have completed ten years of service (or five or more years of service, all of which accrues after December 31, 1995), and of those deriving from such employees, to benefits provided by reason of the provisions of this subsection as the Secretary of Health and Human Services has with respect to individuals insured under the Social Security Act.