42 U.S.C. § 1395o

(a) In general Every individual who— (1) is entitled to hospital insurance benefits under part A, or (2) has attained age 65 and is a resident of the United States, and is either (A) a citizen or (B) an alien lawfully admitted for permanent residence who has resided in the United States continuously during the 5 years immediately preceding the month in which he applies for enrollment under this part, is eligible to enroll in the insurance program established by this part. (b) Individuals eligible for immunosuppressive drug coverage (1) In general Except as provided under paragraph (2), every individual whose entitlement to insurance benefits under part A ends (whether before, on, or after January 1, 2023 ) by reason of section 426–1(b)(2) of this title is eligible to enroll or to be deemed to have enrolled in the medical insurance program established by this part solely for purposes of coverage of immunosuppressive drugs in accordance with section 1395p(n) of this title . (2) Exception if other coverage is available (A) In general An individual described in paragraph (1) shall not be eligible for enrollment in the program for purposes of coverage described in such paragraph with respect to any period in which the individual, as determined in accordance with subparagraph (B)— (i) is enrolled in a group health plan or group or individual health insurance coverage, as such terms are defined in section 300gg–91 of this title ; (ii) is enrolled for coverage under the TRICARE for Life program under section 1086(d) of title 10 ; (iii) is enrolled under a State plan (or waiver of such plan) under subchapter XIX and is eligible to receive benefits for immunosuppressive drugs described in this subsection under such plan (or such waiver); (iv) is enrolled under a State child health plan (or waiver of such plan) under subchapter XXI and is eligible to receive benefits for such drugs under such plan (or such waiver); or (v) (I) is enrolled in the patient enrollment system of the Department of Veterans Affairs established and operated under section 1705 of title 38 ; (II) is not required to enroll under section 1705 of such title to receive immunosuppressive drugs described in this subsection; or (III) is otherwise eligible under a provision of title 38, other than section 1710 of such title to receive immunosuppressive drugs described in this subsection. (B) Eligibility determinations (i) In general The Secretary, in coordination with the Commissioner of Social Security, shall establish a process for determining whether an individual described in paragraph (1) who is to be enrolled or deemed to be enrolled in the medical insurance program described in such paragraph meets the requirements for such enrollment under this subsection, including the requirement that the individual not be enrolled in other coverage as described in subparagraph (A). (ii) Attestation regarding other coverage The process established under clause (i) shall include, at a minimum, a requirement that— (I) the individual provide to the Commissioner an attestation that the individual is not enrolled and does not expect to enroll in such other coverage; and (II) the individual notify the Commissioner within 60 days of enrollment in such other coverage.