No Part D plan is cheapest for everyone. Each plan has its own list of covered drugs, called a formulary. Plans also differ in how much you pay for each drug, which pharmacies you can use, coverage rules, deductibles, and premiums.

Start With an Accurate Medication List

Record each drug's:

  • Exact name
  • Dosage and form
  • Quantity and refill frequency
  • Preferred pharmacy

Include brand-name requirements and medications you expect to start soon.

Compare Total Annual Cost

Use Medicare Plan Compare and enter your prescriptions. Review:

  • Monthly premium
  • Deductible
  • Copayments and coinsurance
  • Estimated yearly drug and premium cost
  • Cost by pharmacy
  • Mail-order pricing

A higher-premium plan can be less expensive overall when it covers your drugs in lower-cost groups, called tiers.

When a Higher Premium Costs Less Overall

Hypothetical 2027 example, not an available plan quote. For the same prescriptions, quantities, and pharmacy:

  • Plan A: $10 monthly premium × 12 = $120, plus $900 estimated covered drug cost sharing = $1,020 for the year.
  • Plan B: $35 monthly premium × 12 = $420, plus $420 estimated covered drug cost sharing = $840 for the year.

Plan B costs $180 less in this example despite its higher premium. If it excludes a medicine or requires an exception that is denied, you may not be able to get that medicine at the cost shown. Use the plan tool’s yearly estimate, including any applicable deductible, because one refill price may not reflect your costs throughout the year.

Check Coverage Rules

For every prescription, look for:

  • Prior authorization: approval before the plan pays
  • Step therapy: trying another covered drug first
  • Quantity limits: how much you can get at one time
  • Specialty pharmacy requirements
  • Whether the drug is excluded

If a drug is not covered, ask your prescriber about alternatives or the plan's exception process.

Review Pharmacies and Plan Quality

Preferred in-network pharmacies can charge less than standard in-network pharmacies. Review the quality measures and member-experience information shown with the plan’s star rating, but do not treat a rating as a guarantee that a particular drug exception will be approved.

Use Medicare's plan comparison tools, then confirm important details with the plan.

Compare Every Year

Formularies, premiums, tiers, and pharmacy contracts can change. Read your plan’s Annual Notice of Change, which explains next year’s changes, and compare during Open Enrollment from October 15 through December 7.

Save or print the results with the coverage year, medication list and pharmacy. If you expect to reach the drug cap, compare premiums and access after accounting for that cap; check the correct year’s threshold. The Medicare Prescription Payment Plan can spread bills across the remaining months of the year, but it does not lower the total cost.

Medicare policy sources last checked: October 8, 2026.