How to Check Drug Coverage Tiers and Formulary Changes for Medicare Part D

What Is a Drug Formulary and Why It Matters for Seniors

A drug formulary is simply the list of medications your Medicare Part D or private insurance plan covers. But it’s not just a list-it’s broken into tiers, and each tier determines how much you pay out of pocket. A drug in Tier 1 might cost you $5, while the same drug in Tier 4 could cost $120. That’s not a typo. The difference isn’t about effectiveness-it’s about how your plan prices it.

Every plan has its own formulary. The same drug, like metformin for diabetes or lisinopril for blood pressure, can be in Tier 1 with one insurer and Tier 2 with another. That’s why checking your formulary before you fill a prescription isn’t optional-it’s critical. If you don’t, you could be paying hundreds more per year than you need to.

Understanding the Tier System: 3, 4, or 5 Tiers?

Most Medicare Part D plans use one of three tier structures: 3-tier, 4-tier, or 5-tier. Here’s how they break down:

3-tier: Tier 1 = generics (lowest cost), Tier 2 = brand-name drugs, Tier 3 = specialty drugs (highest cost)
4-tier: Tier 1 = preferred generics, Tier 2 = non-preferred generics and some brands, Tier 3 = high-cost brand-name drugs, Tier 4 = specialty medications
5-tier: Tier 1 = preferred generics, Tier 2 = non-preferred generics, Tier 3 = preferred brands, Tier 4 = non-preferred brands, Tier 5 = specialty drugs

Specialty drugs (Tier 4 or 5) are usually for complex conditions like cancer, multiple sclerosis, or rheumatoid arthritis. But here’s the twist: weight loss drugs like Wegovy and Ozempic are now being pushed into these highest tiers-even though they’re not technically for cancer. That’s because their price tags are steep, and insurers are trying to control costs.

Don’t assume your drug stays in the same tier year after year. In 2023, about 17% of formulary changes involved moving a drug to a higher tier, meaning your copay jumped overnight.

How to Find Your Plan’s Formulary Online

Every Medicare Part D plan is required to have a free, easy-to-use online formulary tool. Here’s how to use it:

Go to your plan’s website-like Humana, Cigna, or UnitedHealthcare
Look for a link labeled “Formulary,” “Drug List,” or “Find a Drug”
Enter the exact name of your medication (spell it correctly-use the brand name or generic)
Check the tier, copay amount, and any restrictions (like prior authorization or step therapy)

For example, if you take atorvastatin (generic Lipitor), you might see it listed as Tier 1 with a $5 copay. But if you search for the brand-name version, it could be Tier 3 with a $75 copay. That’s why sticking with generics when possible saves money.

Some plans, like Excellus BCBS and Cigna, even let you compare multiple drugs side by side. Use that feature if you’re considering alternatives.

When Formularies Change-And What to Do

Formularies aren’t set in stone. Plans can change them during the year, not just on January 1. The most common triggers: a new generic hits the market, a drug gets recalled for safety reasons, or a manufacturer raises prices.

If your drug is removed or moved to a higher tier, your plan must notify you in writing. That notice should say:

What changed
When the change takes effect
Your right to request an exception

Don’t ignore these letters. Many seniors do-and end up paying way more. If your drug gets moved to a higher tier, you have options:

Ask your doctor for a generic alternative
Request a formulary exception (more on that below)
Switch plans during Open Enrollment (November 15-December 7)

For example, one user on Medicare.gov reported their blood pressure med jumped from $10 to $55 a month after a tier change. They called their pharmacist, who suggested a similar drug already in Tier 1. They switched-and saved $540 a year.

Pharmacist showing elderly patient the cost difference between two tiers of the same medication.

How to Request a Formulary Exception

If your medication is not covered or is in a higher tier than it should be, you can ask for an exception. This isn’t a complicated process, but you need to act fast.

Your doctor must submit a letter explaining why you need that specific drug. For example:

You tried two other drugs in lower tiers and had bad side effects
You have a medical condition that makes other drugs unsafe
The drug you’re on is the only one that works for you

Submit the request through your plan’s website, phone, or mail. Most plans respond within 72 hours for standard requests, or 24 hours if it’s an urgent case.

Approval rates vary. Some plans approve 80% of requests. Others only approve 55%. The key is documentation. If your doctor writes a clear, specific letter, your odds go up.

Pro tip: If you’re denied, you can appeal. And if you’re still denied, you can switch to a different plan during the next enrollment period.

What to Do If Your Drug Is Removed Entirely

If your drug is completely removed from the formulary, your plan must give you a 30-day transition supply. That means you can still get your medication for one more month while you and your doctor figure out a replacement.

Use that time wisely:

Call your pharmacist-they know what similar drugs are covered
Check GoodRx or SingleCare for cash prices on alternatives
Ask your doctor to submit an exception request if you can’t switch

Don’t stop taking your medication. Even if the cost is higher, going without could lead to hospitalization-which costs far more.

Where to Get Free Help

You don’t have to figure this out alone. Every state has a SHIP (State Health Insurance Assistance Program). These are free, unbiased counselors who help seniors understand Medicare coverage.

SHIP advisors helped 1.7 million people in 2022 with formulary questions. They can:

Walk you through your plan’s formulary tool
Compare formularies across plans
Help you file an exception request

To find your local SHIP, call 1-877-839-2675 or visit Medicare.gov/ship.

Pharmacists are another underused resource. Most will check your formulary for free when you drop off a prescription. Ask them: “Is this drug still in Tier 1?” or “Is there a cheaper alternative?”

Senior holding a doctor's letter as a glowing approval stamp opens a path through broken formulary tiers.

Red Flags That You’re Paying Too Much

Here are signs your formulary isn’t working for you:

You pay more than $15 for a generic drug that’s usually $5-$10
Your drug requires prior authorization every time
You’ve been told “we don’t cover that” but other plans do
Your copay jumped by more than $20 without warning

If any of these sound familiar, it’s time to take action. Don’t wait until next year’s Open Enrollment. You can switch plans mid-year if your drug is removed or if your plan makes a major change that affects you.

What’s Changing in 2025 and Beyond

Medicare is moving toward a simpler 4-tier formulary system by 2025. That means fewer confusing categories and clearer pricing. But until then, the system stays complex.

Also, more drugs are being labeled as “specialty”-even if they’re not injectable or high-risk. Weight loss drugs, sleep aids, and even some antidepressants are being pushed into Tier 4 or 5. That’s because their list prices are high, even if their actual cost to insurers is lower.

Insurers are also using AI tools to predict which drugs patients will need-and adjust formularies before you even fill a prescription. That’s good if you get a better deal. But it’s risky if you’re not monitoring your coverage.

Final Checklist: 5 Steps to Stay in Control

Bookmark your plan’s formulary tool and check it every January and after any letter from your insurer
Write down your top 3 medications and their current tier and copay
Ask your pharmacist every time you refill: “Is this still covered the same way?”
Know your exception rights-your doctor can help you get a drug covered even if it’s not on the list
Call SHIP if you’re confused. They’ve seen it all-and they’re free

Medicare Part D is designed to help you save money. But only if you know how to use it. Don’t let a hidden tier change cost you hundreds. Stay informed. Stay proactive. Your wallet-and your health-will thank you.

How often do Medicare Part D formularies change?

Formularies are updated annually on January 1, but changes can happen anytime during the year. Plans must notify you in writing if a drug you’re taking is removed, moved to a higher tier, or gets new restrictions. For safety reasons, changes can happen immediately without notice, but you’ll still get a copy of the update afterward.

Can I switch Medicare plans mid-year if my drug is no longer covered?

Yes, but only under specific circumstances. If your plan removes a drug you’re taking, moves it to a higher tier, or adds a new restriction like prior authorization, you qualify for a Special Enrollment Period. This lets you switch to another Part D plan without waiting for Open Enrollment. You have 63 days from the date you’re notified to make the change.

Why is my generic drug in Tier 2 instead of Tier 1?

Not all generics are treated equally. Plans designate some as “preferred” (Tier 1) and others as “non-preferred” (Tier 2). This is often based on cost negotiations between the insurer and drug manufacturers. A Tier 2 generic might be just as effective but more expensive for the plan to buy. Always ask your pharmacist if a lower-cost generic is available.

Do all Medicare Part D plans have the same formulary?

No. Each plan creates its own formulary, so the same drug can be in different tiers across plans. For example, a blood pressure medication might be Tier 1 on one plan and Tier 3 on another. That’s why comparing formularies during Open Enrollment is essential-not just premiums.

What if I can’t afford my medication after a tier change?

First, ask your doctor for a formulary exception. Second, check if you qualify for Extra Help (Low-Income Subsidy) through Medicare, which can lower your copays. Third, use programs like GoodRx, NeedyMeds, or manufacturer coupons. Many drugmakers offer free or discounted medication to seniors who meet income guidelines. Never skip doses-reach out for help before you run out.