Medicare Part D was created as part of the Medicare Prescription Drug, Improvement and Modernization Act of 2003, with an effective date of January 1, 2006. It is designed to subsidize the cost of prescription drugs for Medicare beneficiaries in the United States.

Medicare Part D was estabilshed as part of the Medicare Prescription Drug Improvement and Modernization Act of 2003 (MMA) and provides assistance paying for prescription medications. Most Medicare drug plans (Medicare drug plans and Medicare Advantage Plans with prescription drug coverage) have their own list of what drugs are covered, called a formulary. Medicare .gov has a tool you can use to determine which drug plans cover your prescription drugs. Also, some people qualify for extra assistance paying for prescription drugs. The application for extra assistance paying for prescription drugs is at: https://secure.ssa.gov/i1020/start

• Medicare Part D’s Importance Extends Far Beyond The Drug Benefit It Provides (Health Affairs 2016)
• What Is the Medicare Modernization Act of 2003?
• Medicare Part D Prescription Drug Benefit (CRS 2014)