Tufts Health Plan Medicare Preferred is an HMO plan with a Medicare contract. Enrollment in Tufts Health Plan Medicare Preferred depends on contract renewal. Benefits, formulary, pharmacy network, premium and/or copayments/coinsurance, may change on January 1 of each year. Tufts Medicare Supplement plans are offered in accordance with Massachusetts law. Members must have Medicare Part A and Part B to enroll in this plan.