How Part D Formularies Affect Your Prescription Drug Costs

How Part D Formularies Affect Your Prescription Drug Costs

Medicare Part D plans have formularies, or lists of covered drugs. Drugs are then divided into tiers. Higher tiers cost you more at the pharmacy, where lower tiers can cost next to nothing.

Your Part D plan formulary can have a massive impact on your out-of-pocket prescription costs. Here’s how it works.

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What’s a Part D Formulary?

Medicare Part D drug plans have formularies, which are lists of drugs that plan will cover. Formularies can be different from carrier to carrier and even from plan to plan.

So, if you have a Part D plan from SilverScript, your list of covered drugs will be different from your friend, who has a Part D plan from WellCare.

And if you and your friend each have different Part D plans from WellCare, your lists of covered drugs can still be different.

Part D formularies can also change each year, which is why you always want to do a drug plan comparison in the fall. From October 15-December 7, you can switch drug plans if another one covers your list of drugs a bit better.

How Much Do Drug Tiers Matter?

Within a Part D plan’s formulary, or list of covered drugs, those drugs will be sorted into tiers.

Higher tiers are typically your brand names (think Abilify), whereas lower tiers will be your generics (think aripiprazole). Middle tiers are somewhere in between.

A Tier 1 drug may only cost you a $1 copay at the pharmacy. A Tier 3 drug may cost you a $45 copay at the pharmacy. A Tier 5 drug could cost you around 25% coinsurance at the pharmacy. For brand name drugs, that can add up to hundreds of dollars each month.

Do I Need to Research Formularies and Drug Tiers?

Part D formularies and drug tiers are essential for keeping your prescription drug costs down. You need a plan that’s compatible with your specific medications.

However, you don’t actually have to sift through formulary lists and drug tier information. For dozens of drug plans, that would probably take weeks.

We can run a no-cost drug comparison and find out which Part D plan is the lowest cost option for you, and it only takes about 5 minutes.

Just tell us your favorite pharmacy and your prescription information, and we can quickly find out which plans will work for you.

The list of plan options will be automatically sorted from lowest out-of-pocket cost to highest out-of-pocket cost, so we don’t have to worry about researching formularies and drug tiers. That work is already done for us.

What If My Prescriptions Change Tiers?

It’s possible for a Part D plan to make changes to their formulary or drug tiers. As we mentioned earlier, going up tiers can significantly change your costs at the pharmacy.

The good news is you can switch drug plans during the Medicare Annual Enrollment Period, which happens from October 15-December 7 every year.

During this time, you can join, switch, or drop a Part D drug plan. We recommend running a new drug comparison every year. Even if your plan doesn’t change, insurance companies are often coming out with even more competitive plans than the year before.  

Take advantage of this competition by ensuring you’re in the lowest cost Part D plan for the following year.


Our licensed insurance agents are prepared to help you find the right health and drug plans. If you got a notice about your formulary or drug tier changing, call us or schedule an appointment online, and we will run a brand new drug plan comparison for you.

Please be aware that we do not offer every drug plan available in every county. Any information we provide is limited to the plans we do offer in our area. Please contact or 1-800-MEDICARE to get information on all of your options.

Running a Part D plan comparison only takes us a few minutes, and our services cost you nothing.

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Disclaimer: We do not offer every plan available in your area. Currently we represent 4 organizations which offer 41 products in your area. Please contact, 1‑800‑MEDICARE, or your local State Health Insurance Program to get information on all of your options. Not connected with or endorsed by the United States government or the federal Medicare program.