(A) For purposes of applying sections 3201(a), 3211(a), and 3221(a), in the case of payments made to an employee or any of his dependents on account of sickness or accident disability, clause (i) of the second sentence of paragraph (1) shall exclude from the term “compensation” only— (i) payments which are received under a workmen’s compensation law, and (ii) benefits received under the Railroad Retirement Act of 1974.

(B) Notwithstanding any other provision of law, for purposes of the sections specified in subparagraph (A), the term “compensation” shall include benefits paid under section 2(a) of the Railroad Unemployment Insurance Act for days of sickness, except to the extent that such sickness (as determined in accordance with standards prescribed by the Railroad Retirement Board) is the result of on-the-job injury.

(C) Under regulations prescribed by the Secretary, subparagraphs (A) and (B) shall not apply to payments made after the expiration of a 6-month period comparable to the 6-month period described in section 3121(a)(4).

(D) Except as otherwise provided in regulations prescribed by the Secretary, any third party which makes a payment included in compensation solely by reason of subparagraph (A) or (B) shall be treated for purposes of this chapter as the employer with respect to such compensation.