Medicare Part D formulary: What Drugs Are Covered and How to Navigate Your Plan

When you enroll in Medicare Part D formulary, a list of prescription drugs covered by your Medicare drug plan. Also known as a drug list, it tells you exactly which medications your plan will pay for—and which ones require extra steps before you can get them. This isn’t just a brochure you ignore. It directly affects how much you pay each month, what pills you can fill at the pharmacy, and whether your favorite medication stays in your budget.

Every Medicare Part D plan has its own formulary, and they’re not all the same. Some cover brand-name drugs first. Others push you to try cheaper generics before approving the name-brand version. That’s called step therapy, a process where you must try one drug before moving to another. Some plans require prior authorization, a doctor’s extra approval before the plan will pay. And all of them group drugs into formulary tiers, levels that determine your out-of-pocket cost. Tier 1 is usually the cheapest—think generic blood pressure pills. Tier 4 or 5? That’s where expensive cancer drugs or specialty meds live, and your share of the cost jumps.

It’s not just about what’s on the list—it’s about what’s not. If your medication gets removed mid-year, you could be stuck paying full price. That’s why checking your formulary every fall during Open Enrollment matters. Plans change. New drugs get added. Older ones get moved to higher tiers or dropped entirely. You can’t assume your plan from last year will work the same this year.

And here’s the real catch: your formulary doesn’t just list drugs—it controls access. Even if your doctor prescribes a drug, your plan might say no unless you’ve tried two others first. Or they might only cover it if you get a special form filled out by your doctor. It’s not bureaucracy for the sake of it. It’s about cost control. But that doesn’t make it easier for you.

What you’ll find in the posts below are real, practical guides on how to work with your Medicare Part D formulary—not fight it. From how to request an exception when your drug isn’t covered, to why authorized generics can save you hundreds, to how to compare plans using the official Medicare Plan Finder tool. You’ll see how people managed their insulin, blood thinners, and antidepressants under strict formulary rules. You’ll learn what to say when the pharmacist says, "This isn’t covered," and how to get your doctor to help you appeal. These aren’t theory pieces. They’re battle-tested tips from people who’ve been there.