; and (B) the Secretary shall be treated as the issuer of such plan. (4) Medicaid managed care States are prohibited from buying their Medicaid beneficiaries ages 50 to 64 into Medicare under this section, and individuals otherwise eligible for enrollment under a State plan under title XIX are prohibited from coverage under this title pursuant to enrollment under this section. The preceding sentence shall not apply to Medicaid beneficiaries whose Medicaid coverage or eligibility does not meet the definition of minimum essential coverage under a government-sponsored program under section 1.5000A–2 of title 26, Code of Federal Regulations (or any successor regulation). (5) Coordination with market reforms, etc Notwithstanding Treasury Notice 2015–17, no provision of law shall prevent an employer from maintaining an arrangement under which the employer pays or reimburses any portion of the premiums for coverage under this section for retired employees of the employer, or prevent such payment or reimbursement from being excluded from the gross income of the individual enrolled in such coverage for purposes of the Internal Revenue Code of 1986. (g) Guaranteed issue of medigap policies upon first enrollment and each subsequent enrollment In the case of an individual who enrolls under this section (including an individual who was previously enrolled under this section), paragraphs (2)(A), (2)(D), (3)(B)(ii), and (3)(B)(vi) of section 1882(s)— (1) shall be applied by substituting 50 for 65 ; (2) if the individual was enrolled under this section and subsequently disenrolls, shall apply each time the individual subsequently reenrolls under this section as if the individual had attained 50 years of age on the date of such reenrollment (and as if the individual had never previously enrolled in a Medicare supplemental policy)