42 C.F.R. § 427.201 – Computation of beneficiary coinsurance and adjusted Medicare payment for Part B rebatable drugs with price increases faster than inflation.

(a) Methodology. CMS must use the methodology set forth in this section to calculate the inflation-adjusted beneficiary coinsurance and associated adjusted Medicare payment percentage for Part B rebatable drugs as set forth in §§ 410.152(m), 419.41(e), and 489.30(b)(6) of this chapter.
(b) Calculation of inflation-adjusted beneficiary coinsurance. To calculate the inflation-adjusted beneficiary coinsurance for Part B rebatable drugs with respect to a calendar quarter, CMS compares the payment amount, as set forth in paragraph (b)(3) of this section, to the inflation-adjusted payment amount for the applicable calendar quarter.
1. (1) If the payment amount exceeds the inflation-adjusted payment amount, the inflation-adjusted beneficiary coinsurance is calculated by multiplying the inflation-adjusted payment amount by 0.20.
2. (2) If the inflation-adjusted payment amount does not exceed the payment amount, the adjustment to the beneficiary coinsurance set forth in paragraph (b)(1) of this section is not applied.
3. (3) CMS will use the published payment amount in quarterly pricing files published by CMS as the payment amount in this determination.
(c) Exclusions. Any drug that is excluded from Part B rebatable drugs as set forth in § 427.101(b) is not subject to inflation-adjusted beneficiary coinsurance.