American Insurance · PUBLISHED 15 JUL 2026 · VERIFIED 15 JUL 2026 · US EDITION

How to Choose a Part D Plan That Actually Covers Your Drugs

▶

A single drug can make the wrong Part D choice expensive fast: under Medicare’s 2026 standard benefit, you still pay 25% of covered drug costs until your out-of-pocket spending reaches $2,100, so a plan with the wrong formulary or pharmacy network can turn routine prescriptions into a four-figure bill.

The number that matters

The central number is $38.99: the 2026 Medicare Part D base beneficiary premium, a benchmark premium used to measure the cost of Part D coverage nationwide.

How it quietly costs you

The first hidden money leak is formulary mismatch: every Part D plan has its own drug list, and Medicare says each plan’s formulary can differ even though all plans must cover a wide range of drugs. If your prescription is placed on a higher tier, the plan can charge more at the pharmacy because tiering changes your copay or coinsurance, so the same medication can cost materially more in one plan than another.

A concrete benchmark is that Medicare Part D plans generally use tier structures, and beneficiaries are told to compare the plan’s covered drugs and tiers before enrolling. The “old vs better” move is simple: instead of choosing a plan by premium alone, choose one where your exact drugs are on the formulary and placed in lower tiers.

The second, compounding trap

The second compounding cost is pharmacy-network pricing plus the Part D cost-sharing ladder. Medicare and plan guidance both stress that preferred pharmacy status and drug pricing can change what you pay, and under the 2026 standard benefit you pay 25% of covered drug costs in initial coverage until you reach the $2,100 out-of-pocket cap.

That means a “cheap” plan can still cost more if your pharmacy is out of network or not preferred, because you may lose lower negotiated prices and hit the out-of-pocket threshold faster. For 2026, KFF reports a typical stand-alone Part D plan premium of $38.99 in the base-beneficiary benchmark, but that premium does not guarantee lower total drug spending if the network and formulary are poor for your prescriptions.

What this looks like in practice

Maria, 68, retired school aide, $32,000 income, 4 prescriptions, $1,200 annual drug spend, stand-alone Part D, 17 years from retirement planning horizon.

• Maria discovers that one of her name-brand drugs is on a higher tier in one plan, while another plan treats it more favorably; Medicare says every plan has its own formulary, so the same medication can be covered differently across plans.

• Maria discovers that her preferred pharmacy is not the same price in every plan; plan guidance says pharmacy choice affects what she pays, so using a preferred pharmacy can reduce out-of-pocket costs compared with an out-of-network option.

• Maria discovers that her total exposure is capped only after she reaches the standard-benefit threshold: in 2026, she still pays 25% of covered drug costs until she hits $2,100 in out-of-pocket spending, which is much higher than many people expect when they shop only on premium.

The full cost of doing nothing

For a person like Maria, the combined lifetime cost of choosing a bad formulary and a bad pharmacy network can easily run into the thousands of dollars over retirement, because the plan can force higher copays/coinsurance on multiple drugs every year until the $2,100 annual out-of-pocket cap is reached.

A conservative modeling basis is this: assume she pays an extra $30–$50 per month from higher tiering or worse pharmacy pricing on just one or two medications, which equals roughly $360–$600 per year; over 15 years, that is about $5,400–$9,000 before counting premium differences or annual increases.

What to do about it

• Compare your exact prescriptions in Medicare Plan Finder and check each drug’s tier and coverage status in the plan formulary.

• Go to Medicare’s Plan Finder.

• Enter your prescriptions exactly as written, including dosage and quantity.

• Compare plans by drug coverage, tier, and total estimated cost.

• What good looks like: every medication is covered, and the lowest-tier option is available whenever possible.

• Check your pharmacy against each plan’s preferred network before enrolling.

• Open each plan’s pharmacy list.

• Search for your usual pharmacy and at least one preferred alternative nearby.

• Compare copays at preferred vs non-preferred pharmacies.

• What good looks like: your regular pharmacy is preferred, or a nearby preferred pharmacy gives clearly lower total costs.

• Estimate whether a lower premium actually saves money over the year.

• Use Medicare Plan Finder’s estimated annual cost view.

• Add premium, deductible, and expected copays for your current prescriptions.

• Compare that total against another plan with a higher premium but lower drug costs.

• What good looks like: the plan with the lowest total annual cost, not just the lowest monthly premium.

A myth worth clearing up

Myth: The cheapest Part D premium is usually the cheapest plan overall. Fact: Medicare and plan guidance show that formulary tiering and pharmacy network pricing can change your total cost far more than premium alone, so the lowest-premium plan can be the most expensive once your prescriptions are counted.

Sources

• Medicare.gov
• Medicare.gov
• KFF

Researched 2026-07-15.

Corrections & disclosure: an AI-assisted, human-reviewed guide. Every figure is dated and sourced above. Spot something out of date or wrong? Tell us and we’ll correct it — corrections are noted here and in the video description.