How can I be sure that my Medicare prescription drug plan will cover my expenses?

  • April 3, 2018

Q: How can I be sure that my Medicare prescription drug plan will cover my expenses?

A: Generally, a prescription written by your doctor will be covered under your drug plan if you follow these requirements:

  • Make sure your doctor is up to date on the prescription drugs your specific plan covers – each plan has a different formulary (covered drug list), which means your doctor may need to select a specific drug from among various options in the drug class.
  • Be certain your doctor is aware of how much medication you are allowed under your plan to receive at a time.
  • The doctor is required to prescribe lower-cost (generic) drugs rather than name-brand drug and must show that the drug he or she has prescribed is medically necessary.

Drug formularies change from one year to the next, and different Medicare Part D plans offer different levels of coverage for different drugs. So it’s important to shop around during open enrollment (October 15 to December 7) to make sure you’re enrolling in the plan that will provide you with the best coverage for the coming year.


If your prescription medication is excluded by your Part D plan, a prescription discount card may lower the price of your medication.


Medicare has a plan finder tool where you can enter your medications and see how much your out-of-pocket costs will be for each of the plans available in your area. If you’re currently taking medications, using this tool during open enrollment is essential.

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If you’re not taking medications, you still need to enroll in a Part D plan as soon as you become eligible for Medicare (unless you have creditable drug coverage from a plan offered by your employer or your spouse’s employer or a retiree drug plan), although people in this situation often just pick the cheapest plan available. If you skip Part D altogether because you’re not taking any medications, you could end up paying a lot more in the long run, due to lack of coverage as well as the late enrollment penalty.

A person who skips Part D coverage and then ends up being prescribed expensive medication mid-year will be unable to enroll in a Part D plan until the next open enrollment period, with coverage effective the following January. And for every month that you were eligible to enroll in Part D but didn’t (and didn’t have creditable drug coverage from another source), you’ll pay a surcharge equal to 1 percent of the national average Part D premium — on top of your regular Part D premium.

So if you wait three years to sign up for Part D coverage because you weren’t taking medications during those three years, you’ll pay the regular Part D premium for the plan you pick, plus a surcharge equal to 36 percent of the average premium. That surcharge will continue for as long as you have Part D, and will increase over time as the average price of Part D plans increases.