How to Shop Medicare Prescription Drug Coverage: A Practical Part D Guide

The best drug plan is personal

Medicare prescription drug coverage is not a one-size-fits-all purchase. A plan that works well for a neighbor or spouse may cost more for you because each plan has its own premium, deductible, drug list, tiers, pharmacy network, and coverage rules. Your ZIP code and the prescriptions you take can change the comparison significantly.

Start with your own medications and preferred pharmacies, then compare the expected cost for the entire year. The plan with the lowest premium is not automatically the plan with the lowest total cost.

Build an exact prescription list

Before comparing plans, make a current list of every prescription you expect to take. Include the exact drug name, dosage, form, quantity, and how often you refill it. For example, a tablet and an extended-release tablet with a similar name may be treated differently by a plan.

Separate drugs you receive at a retail or mail-order pharmacy from medications administered in a doctor's office, hospital outpatient department, or infusion setting. Some of those medications may be covered under Medicare Part B rather than Part D.

Ask your prescriber whether a generic, biosimilar, or lower-cost therapeutic alternative could be appropriate, but do not change a medication solely to fit a plan without medical guidance.

Compare total annual cost, not premium alone

A useful comparison combines the monthly premium with the estimated deductible, copayments, and coinsurance for your prescriptions. Medicare's Plan Compare tool can estimate monthly and yearly drug costs when you enter your medications and pharmacies.

Look at how costs may change throughout the year, especially if you take an expensive brand-name or specialty drug. A plan with a higher premium can sometimes produce a lower overall annual cost, while a low-premium plan can become expensive when an important drug is placed on a higher tier or subject to coinsurance.

Estimates are valuable for comparison, but they are not guarantees. Drug prices, prescribing needs, plan formularies, and pharmacy arrangements can change. Review the plan's official documents before enrolling.

Confirm the formulary and tier for every drug

A plan's formulary is its list of covered drugs. Check every medication—not just the most expensive one—and confirm the version, dosage, and quantity. Then review the tier assigned to each drug because lower tiers generally have lower cost sharing than non-preferred or specialty tiers.

If a medication is not on the formulary, see whether the plan covers an alternative and discuss it with your prescriber. You or your prescriber may also be able to request a formulary or tiering exception, but approval is not automatic.

Plans can make permitted formulary changes. Review notices from the plan and recheck coverage during each Annual Open Enrollment Period even when you are satisfied with your current plan.

Check prior authorization, step therapy, and quantity limits

Coverage can depend on more than whether a drug appears on the formulary. A plan may require prior authorization before it will cover a medication, step therapy that asks you to try another covered drug first, or a quantity limit on how much it covers at one time.

These rules can affect both access and timing. If an important medication has a restriction, ask what documentation is required, whether your prescriber expects to request an exception, and what happens while the request is reviewed. A transition fill may be available in certain situations when new coverage begins, but it is temporary and should not replace a long-term plan with your prescriber.

Compare pharmacies as carefully as plans

The same prescription can have different costs at different pharmacies under the same plan. First confirm that your pharmacy is in the plan's network. Then see whether it is a preferred in-network pharmacy, where the plan may offer lower copayments or coinsurance.

Compare at least two convenient local pharmacies and any mail-order option the plan offers. Consider delivery reliability, refill timing, access while traveling, and whether a 90-day supply is available—not price alone. If you use a specialty pharmacy, confirm which specialty pharmacy the plan requires.

Out-of-network pharmacy purchases are generally more expensive and may require you to pay the full price, except in limited circumstances described by the plan.

Understand the deductible and out-of-pocket limit

For 2027, no Medicare drug plan may have a deductible above $700, and some plans have a lower deductible or no deductible. A plan may also apply its deductible differently across drug tiers.

After covered out-of-pocket Part D spending reaches $2,400 in 2027, you enter catastrophic coverage and pay nothing out of pocket for covered Part D drugs for the rest of the calendar year. These figures can change annually, so confirm the amount for the coverage year you are shopping.

The Medicare Prescription Payment Plan can spread eligible out-of-pocket Part D costs across the calendar year. It may make monthly budgeting easier, but Medicare notes that it does not reduce the total cost of your prescriptions.

Choose the right way to receive Part D coverage

People with Original Medicare can generally add a stand-alone Medicare drug plan. Many Medicare Advantage plans include prescription drug coverage within the health plan. The choice affects more than prescriptions: an Advantage plan can also change provider networks, referrals, prior authorization, medical cost sharing, and the plan's annual medical out-of-pocket limit.

Do not join a stand-alone drug plan without checking how it interacts with your current coverage. In many Medicare Advantage HMO and PPO plans, joining a separate drug plan can cause disenrollment from the Advantage plan. Employer, union, VA, TRICARE, and other drug coverage may also have special coordination rules. Contact the benefits administrator before making a change that could affect coverage for you or your dependents.

If you go 63 or more consecutive days without Medicare drug coverage or other creditable prescription coverage after your eligible enrollment period, you may owe a Part D late-enrollment penalty when you join later.

Use Medicare.gov to see all plans in your area

Medicare.gov's Plan Compare is the broadest self-service starting point because it displays all Medicare Advantage and stand-alone prescription drug plans available for the ZIP code entered. Add your exact drugs and pharmacies to receive a personalized cost comparison, then review the plan details and official documents before enrolling.

Sonon Insurance offers convenient self-enrollment links for a limited selection of Medicare prescription drug plans and carriers on our website. Those links can be useful when one of the available options fits your needs, but they do not represent every plan available in your area. To shop the full market, use Medicare.gov/plan-compare or call 1-800-MEDICARE (1-800-633-4227).

If you want help understanding plan structure or the options we service, Sonon Insurance can assist where we are licensed and appointed. Plan availability and the scope of our assistance vary by area and carrier.

Review coverage every fall

Medicare plans can change premiums, deductibles, formularies, tiers, pharmacy networks, and coverage rules from one year to the next. Your prescriptions and preferred pharmacy can change too. Read the Annual Notice of Change and run a fresh comparison each year rather than allowing coverage to renew on autopilot.

Medicare Open Enrollment runs from October 15 through December 7 each year. Changes made during that period generally take effect January 1. Other enrollment opportunities may apply when you first become eligible or after certain qualifying circumstances.

Before submitting an enrollment, save the plan name, contract and plan identifiers, confirmation number, effective date, premium-payment instructions, and the drug and pharmacy list used for the comparison.