Somewhere in a kitchen drawer, or the stack of mail by the door, there is an envelope that looks exactly like junk. It has a government-ish return address and a dense block of type. Every year, millions of people on Medicare toss it unopened, because the plan worked fine last year and nothing feels wrong.

That envelope is often the only warning you get that the deal is about to change.

The quiet rule behind the envelope

Medicare drug coverage (Part D) is sold by private insurers, and those insurers can change their terms every calendar year. They can change the monthly premium and the deductible. They can move a drug to a different tier, add restrictions, or drop it from the covered list.

Your plan has to tell you in advance. It mails an Annual Notice of Change, which is due by the end of September. Open enrollment runs from October 15 to December 7, and whatever you choose takes effect on January 1.

You can switch plans only in a narrow window, and the notice is the document that tells you whether you should. Nothing about it announces itself as urgent.

Why "it worked last year" is a trap

This is a quiet kind of loyalty. You trust the plan, the pharmacy, and the routine. Behavioral economists call the pull toward the default status quo bias. People tend to stay with the current option even when a better one is easy to see, because switching takes effort and a mistake feels like your fault.

Part D plans lean on that tendency. Your plan renews automatically. Doing nothing is a decision, and it is the one that lets someone else's pricing changes become your pricing.

Here is what that looks like. Say you take a generic for blood pressure, a statin, and a diabetes drug. Last year your plan charged a flat copay on all three. This year the notice may say one of them now sits in a higher tier, or that the deductible applies to it before coverage begins. The medication is identical, but what you pay for it is not.

The two numbers most people never put side by side

When people compare plans, they usually look at the premium. It is the easiest figure to read, and it is only part of the cost. What you actually spend on prescriptions in a year is roughly:

  • the premiums you pay, plus
  • the deductible you pay before coverage starts, plus
  • the copays or coinsurance you pay at the counter for each fill.

A plan with a low premium can cost more overall if your particular drugs are on a high tier. A plan with a higher premium can cost less if it covers your drugs well. The only way to know is to price your own list of medications, not an average person's.

Medicare's online Plan Finder at Medicare.gov does exactly this. You enter your drugs, doses, and pharmacy, and it estimates your total yearly cost under each plan in your area. It takes about fifteen minutes the first time. Your State Health Insurance Assistance Program (SHIP) offers free, unbiased counseling if you would rather talk it through with a person.

What changed in Part D, and what didn't

The rules have moved in your favor in recent years. Since 2025, Part D has had an annual cap on what you pay out of pocket for covered drugs. It was $2,000 in 2025 and adjusts yearly, so check Medicare.gov for the current figure. You can also spread your costs across the year with the Medicare Prescription Payment Plan, which lets you pay in monthly installments rather than all at once at the pharmacy.

Those protections matter most if you take expensive brand-name or specialty drugs. For many people on inexpensive generics, though, the cap is far above what they will ever spend. Their real exposure is the everyday copay, tier placement, and deductible. Those are the details a cap does nothing about.

The generic that costs less than your copay

There is a wrinkle that surprises people after years of assuming insurance always wins. For some common generics, the pharmacy's plain cash price can be lower than your plan's copay. The pharmacy's own price for a cheap generic is sometimes just a few dollars, while the plan assigns it a set copay by tier.

There is a trade-off. Money you spend outside your plan generally doesn't count toward your deductible or your out-of-pocket total. If you take costly drugs and expect to reach the cap anyway, paying cash for a cheap generic may not help you. If your whole list is inexpensive generics and you won't hit the cap, it can be a real saving.

The point is that you can't know which case you're in without seeing both numbers. That means the plan's price and a realistic cash price for the same drug.

Your next moves

Do these before December 7. Each one takes less than an hour.

  • Find the notice. Look for your Annual Notice of Change (it may be labeled that way, or titled something like "Evidence of Coverage"). If you tossed it, log in to your plan's member site or call the number on your card and ask for a copy.
  • Write down your medication list. For each drug, note the name, dose, and how many pills you take per month. Include the pharmacy you use. Plan Finder asks for all of this.
  • Run Plan Finder. Go to Medicare.gov, enter your list, and compare your current plan's estimated yearly cost with two or three alternatives. Look at the total, not just the premium.
  • Check the cash price for your cheapest drugs. For each generic, look up the typical cash price and compare it to your copay. Then call one or two nearby pharmacies and ask what they charge without insurance.
  • Book a free SHIP session if anything is unclear. Search for your state's SHIP counselor. They don't sell plans and can walk through your options with you.

If you find a better plan, you can switch during open enrollment. If you stay put, you'll be doing it on purpose this time.

Where a price check fits

When I think about why people skip all this, it's rarely laziness. It's that the whole system hides prices behind codes, tiers, and mailers, so staying put feels safer than learning a language no one taught you. SnapRx exists for one small piece of that. You photograph a prescription label and it shows the typical national-average cash price based on CMS's public NADAC data, then lists real pharmacies nearby to call. It won't choose a Part D plan for you, and it isn't a substitute for Plan Finder. It gives you the one number the plan comparison doesn't: roughly what the drug costs without insurance, so you can tell whether your copay is a deal. If that's useful as you work through your list, you can try it at https://snaprx.lumenlabs.works.