Medicare Part D is optional prescription drug coverage offered by private insurance companies approved by Medicare. Part D plans are designed to help pay for covered outpatient prescription drugs, including many generic and brand-name medications.

You can get Medicare drug coverage in either of these ways:

• A standalone Medicare Prescription Drug Plan (PDP), often used with Original Medicare and sometimes paired with Medicare Supplement Insurance. You generally must have Medicare Part A and/or Part B to join a standalone PDP.
• A Medicare Advantage plan that includes prescription drug coverage (MA-PD). You generally must have both Part A and Part B and live in the plan service area to join a Medicare Advantage plan.

Part D plans are not all the same. A plan may cover one medication at a lower tier while another plan may place the same medication on a higher tier, require prior authorization, limit the quantity, or not cover it at all. Pharmacy choice can also affect your estimated cost.

Before enrolling, review each plan carefully so you understand:

• Whether each prescription is on the plan formulary, also called the drug list.
• The drug tier for each medication and whether that tier has a copay or coinsurance.
• The correct drug strength, dosage form, quantity, and days supply shown in the quote.
• Whether the plan uses prior authorization, step therapy, or quantity limits.
• Whether your pharmacy is in network and whether it is preferred or standard cost sharing.
• The monthly premium, deductible, estimated copays or coinsurance, and estimated annual drug cost.

1. Enter your ZIP code and confirm your county. Medicare plan availability can vary by county and service area.
2. Add every prescription you take. Use the exact drug name shown on your bottle or prescription label, including whether it is brand-name or generic.
3. Confirm the strength and form. For example, confirm whether the medication is a tablet, capsule, inhaler, injection, cream, extended-release tablet, or other form, and verify the strength such as 10 mg, 100 mcg, or units/mL.
4. Confirm dosage and quantity. Enter how often you take it, the quantity filled, and the expected days supply, such as 30-day or 90-day fills.
5. Choose your pharmacy options. Compare your preferred local pharmacy, other nearby pharmacies, and mail-order if available. Costs may differ by pharmacy.
6. Review the results for each plan. Look for coverage status, tier, deductible status, copay or coinsurance, quantity limits, step therapy, prior authorization, and estimated annual cost.
7. Save or print your comparison. Keep a copy of the plan name, plan year, drug list results, pharmacy used for the quote, and enrollment confirmation.

Many Part D plans group covered drugs into tiers. Tiers can vary by plan, but they often follow a structure similar to this:

Common Part D Cost Terms for 2027

Monthly premium: The amount you pay each month to have the plan. The premium is separate from your copays, coinsurance, and deductible.

Deductible: The amount you pay for covered drugs before the plan begins paying. Some plans have no deductible or waive the deductible for certain tiers. For 2027, no Medicare drug plan may have a deductible higher than $700.

Copay: A fixed dollar amount you pay for a covered prescription at the pharmacy.

Coinsurance: A percentage of the drug cost that you pay for a covered prescription.

Preferred pharmacy: A network pharmacy where a plan may offer lower cost sharing. Other pharmacies may be available in the network, but costs can differ.

Out-of-pocket maximum for covered Part D drugs: For 2027, covered Part D drug out-of-pocket costs are capped at $2,400. This does not include monthly premiums, non-covered drugs, or drugs covered under Medicare Part B

Use this checklist before you submit an online enrollment application: