Drug coverage deserves its own review even if you take few medicines today. The premium tells you only what it costs to keep the plan. The formulary, pharmacy arrangement and coverage rules determine how the plan works when you fill a prescription.
Two common ways to get Part D
You can join a separate Medicare drug plan alongside Original Medicare, or receive drug coverage through most Medicare Advantage plans. You need Part A or Part B for a separate drug plan. Medicare Advantage requires both. Not every health plan combines with a standalone Part D plan, so confirm compatibility before applying.
Read the drug list carefully
A formulary is the plan’s covered drug list. A tier groups drugs for cost sharing; it is not a measure of which medicine is best for you. Prior authorization requires an approval before coverage, a quantity limit controls the covered amount, and step therapy may require trying another covered drug first. Your prescriber handles medical decisions and supporting clinical information.
Write down the exact medicine, strength, form, dose and refill quantity. Similar names or a different delivery method can change the result. Compare both retail and mail-order arrangements only if they are practical for you.
The 2026 drug spending limit
In 2026, the Part D annual out-of-pocket threshold is $2,100 for covered Part D drugs. Premiums and drugs the plan does not cover do not count as covered drug spending toward that limit. This is not a cap on all medical expenses. Keep the medical and prescription budgets separate.
If you have other drug coverage
Ask for the written creditable coverage notice before delaying Part D. Creditable means the coverage is expected to pay, on average, at least as much as standard Medicare drug coverage. Keep the notice. The rules for postponing Part B and the rules for avoiding a Part D penalty are different.
A useful drug-plan review
- Prepare an accurate medication list without posting it publicly.
- Check coverage and restrictions for every prescription.
- Compare estimated yearly spending, not just one month’s refill.
- Verify your preferred pharmacy’s status.
- Review help with costs if the estimate is unaffordable.
Common question: Does the Medicare Prescription Payment Plan reduce what I owe? No. It spreads eligible out-of-pocket Part D expenses over the remaining calendar year. Extra Help is a different program that may lower costs.
Sources and update notes
Published by My Coverage Relay. Updated September 24, 2026. This guide explains general rules; individual eligibility, plan terms and state protections require a specific review.