Medicare Part D Prescription Drug Plans are designed to help you manage the cost of your medications. Since Original Medicare does not include prescription coverage, enrolling in a Part D plan is essential—both for financial protection and to avoid late-enrollment penalties later on. These plans are offered by private insurance companies, and each one has its own drug list, pricing structure, and pharmacy network. That’s why choosing the right plan isn’t always as simple as picking the lowest premium.

Part D plans organize medications into tiers, from low-cost generics to high-cost specialty drugs. Because each plan’s formulary is different, the cost of your specific prescriptions can vary significantly from one plan to another. A plan that looks inexpensive on the surface may actually cost more at the pharmacy if your medications aren’t placed in favorable tiers.