Months of Part B coverage
This variable is the number of months during the year that the beneficiary had Medicare Part B coverage. (This is sometimes referred to as supplemental medical insurance coverage - or SMI coverage.) CCW derives this variable by counting the number of months where the beneficiary had Part B coverage (i.e., the BUYINXX variable equaled 2, B, 3, or C).
Source: CMS Common Medicare Environment (CME) (derived)