Individuals under 65 years

(A) is entitled to, and has for 24 calendar months been entitled to, (i) disability insurance benefits under section 423 of this title or (ii) child’s insurance benefits under section 402(d) of this title by reason of a disability (as defined in section 423(d) of this title ) or (iii) widow’s insurance benefits under section 402(e) of this title or widower’s insurance benefits under section 402(f) of this title by reason of a disability (as defined in section 423(d) of this title ), or

(B) is, and has been for not less than 24 months, a disabled qualified railroad retirement beneficiary, within the meaning of section 231f(d) of title 45 , or

(C) (i) has filed an application, in conformity with regulations of the Secretary, for hospital insurance benefits under part A of subchapter XVIII pursuant to this subparagraph, and (ii) would meet the requirements of subparagraph (A) (as determined under the disability criteria, including reviews, applied under this subchapter), including the requirement that he has been entitled to the specified benefits for 24 months, if— (I) medicare qualified government employment (as defined in section 410(p) of this title ) were treated as employment (as defined in section 410(a) of this title ) for purposes of this subchapter, and (II) the filing of the application under clause (i) of this subparagraph were deemed to be the filing of an application for the disability-related benefits referred to in clause (i), (ii), or (iii) of subparagraph (A),

shall be entitled to hospital insurance benefits under part A of subchapter XVIII for each month beginning with the later of (I) July 1973 or (II) the twenty-fifth month of his entitlement or status as a qualified railroad retirement beneficiary described in paragraph (2), and ending (subject to the last sentence of this subsection) with the month following the month in which notice of termination of such entitlement to benefits or status as a qualified railroad retirement beneficiary described in paragraph (2) is mailed to him, or if earlier, with the month before the month in which he attains age 65. In applying the previous sentence in the case of an individual described in paragraph (2)(C), the “twenty-fifth month of his entitlement” refers to the first month after the twenty-fourth month of entitlement to specified benefits referred to in paragraph (2)(C) and “notice of termination of such entitlement” refers to a notice that the individual would no longer be determined to be entitled to such specified benefits under the conditions described in that paragraph. For purposes of this subsection, an individual who has had a period of trial work which ended as provided in section 422(c)(4)(A) of this title , and whose entitlement to benefits or status as a qualified railroad retirement beneficiary as described in paragraph (2) has subsequently terminated, shall be deemed to be entitled to such benefits or to occupy such status (notwithstanding the termination of such entitlement or status) for the period of consecutive months throughout all of which the physical or mental impairment, on which such entitlement or status was based, continues, and throughout all of which such individual would have been entitled to monthly insurance benefits under this subchapter or as a qualified railroad retirement beneficiary had such individual been unable to engage in substantial gainful activity, but not in excess of 78 such months. In determining when an individual’s entitlement or status terminates for purposes of the preceding sentence, the term “36 months” in the second sentence of section 423(a)(1) of this title , in section 402(d)(1)(G)(i) of this title , in the last sentence of section 402(e)(1) of this title , and in the last sentence of section 402(f)(1) of this title shall be applied as though it read “15 months”.