This article is for educational purposes only and does not constitute medical, legal, or financial advice. Every family situation is different, and you should consult with appropriate professionals about your specific circumstances.

Medicare Part D — Prescription Drug Coverage and the Coverage Gap

My neighbor's mother takes five medications for her various conditions. She has good Medicare coverage, good Part D coverage, and a decent income. But when she filled her prescriptions in August, she suddenly hit something called the "coverage gap" and had to start paying almost full price for her medications. Nobody had explained to her that this even existed. She thought her Part D plan covered her prescriptions, period. The surprise of suddenly owing hundreds of dollars for medications she'd been paying twenty dollars for was a shock.

This is Part D in a nutshell. It's prescription drug coverage, which sounds straightforward. But the structure of Part D is weird and confusing, and it includes a coverage gap that catches people by surprise. Understanding how Part D actually works, why the gap exists, and what your parent can do about it is important. Medications aren't cheap. If your parent is taking multiple prescriptions, understanding the cost structure can save hundreds of dollars.

The good news is that Part D has been improving. Recent changes mean less dramatic gaps in coverage. But understanding how your parent's specific plan works requires looking at the actual details, not just the marketing.

How Part D Works: The Phases You'll work through

Part D is run by private insurance companies, not by Medicare directly. Your parent chooses a Part D plan from the companies offering them in their state. If your parent chooses Medicare Advantage instead of Original Medicare, prescription coverage is usually already built in. If your parent chooses Original Medicare, they need to choose a separate Part D plan.

Part D has phases, and understanding them is important.

The first phase is the initial coverage phase. Your parent goes to the pharmacy, and their plan covers their medications. The amount your parent pays depends on their specific plan and their specific drugs. The plan has a formulary, which is a list of covered drugs and what you pay for each. A generic medication might have a $15 copay. A brand-name medication might have a $50 or $100 copay. Your parent pays something; the plan pays the rest.

This phase lasts until the amount your parent and the plan have spent together on covered drugs hits a threshold. As of 2025, that threshold is around $6,500. So between what your parent pays out of pocket and what the insurance company pays, once you hit $6,500 in spending, you move to the next phase.

The second phase is the coverage gap, and this is where things go wrong. Once the total spending hits that $6,500 threshold, your parent is supposed to enter the coverage gap. This is where it gets confusing. In the coverage gap, your parent would pay higher copays—potentially 25% of the drug cost instead of the flat copay they were paying before. This would continue until total out-of-pocket spending hit another threshold, around $7,800. Once that threshold was reached, they'd enter catastrophic coverage, where the plan covers almost everything.

But here's what has improved: the coverage gap is shrinking. Starting in 2025, there's now an annual out-of-pocket drug spending cap of $2,000. This means your parent won't fall into the coverage gap as dramatically as they used to. The structure is getting simpler and less punishing.

Still, understanding your parent's specific plan and how much they might pay is important.

The Formulary: Why Two Plans Look Identical But Cost Differently

This is the part that makes people crazy. You can look at two Part D plans side by side, and they both say they cover the same conditions. But they have different formularies.

A formulary is the list of medications the plan covers and what tier they're on. Tier 1 might be cheap generics with small copays. Tier 2 might be preferred brand names with bigger copays. Tier 3 might be non-preferred drugs with even bigger copays. Tier 4 might be specialty drugs with huge copays.

Two similar plans might both say they cover diabetes. But one might have your parent's specific diabetes medication on Tier 1, and the other might have it on Tier 3. That's a huge cost difference.

This is why looking at the plan brochure isn't enough. Your parent needs to enter their actual medications into the plan finder tool. Does Plan A cover their specific diabetes medication, at what tier, for what copay? Does Plan B cover it differently? This is the detail that actually matters.

Formularies also change every year. A medication your parent's plan covered last year might not be covered this year. Or it might be moved to a higher tier with a bigger copay. Or the plan might be discontinued entirely. This is why annual review is essential.

The Coverage Gap and Recent Changes

The coverage gap, also called the "donut hole," used to be a place where people got financially devastated. You'd be paying copays, hit the threshold, and suddenly you're in the gap paying 25% of drug costs. A medication that cost you $20 a month suddenly cost you $100. People chose not to fill prescriptions. They cut pills in half. They did without medications they needed.

The government started fixing this in 2011, gradually improving the coverage in the gap. Each year got better. Recently the improvements accelerated.

In 2024, Medicare started providing better coverage in the gap. In 2025, the situation improved further with the annual out-of-pocket cap. Going forward, there's a $2,000 annual cap on what your parent pays out of pocket for covered drugs. Once they hit $2,000 in out-of-pocket spending, the plan covers covered medications at 100%.

This doesn't mean the gap disappears completely. But it means the gap is less devastating. Your parent won't hit the gap and suddenly face ruinous costs.

It's worth checking what the actual out-of-pocket costs would be under your parent's specific plan and medications. But generally, the trend is improving, not getting worse.

Strategies That Actually Save Money

The most important strategy is comparing plans based on your parent's actual medications, not on the plan brochures. Use the Medicare.gov plan finder. Enter every medication your parent takes. See which plans are cheapest for your parent's specific situation. Different plans work for different people depending on their medications.

Generics are usually much cheaper than brand names. If your parent's doctor prescribes a brand-name medication, ask whether a generic version exists. Often it does, and it's identical to the brand name, just cheaper. Your parent's copay might be $15 for the generic and $60 for the brand name.

Some medications have manufacturer assistance programs. The drug manufacturer offers discounts or free medication for people who can't afford it. Your parent's doctor or pharmacist can help find these programs.

Some pharmacies are cheaper than others for your parent's specific medications. A big national chain might charge differently than a small local pharmacy. It's worth asking or checking.

Bulk ordering can save money. Some medications are cheaper per dose if your parent gets a 90-day supply instead of 30-day. Talk to the pharmacist about what's available.

Planning ahead matters. If your parent is approaching the out-of-pocket spending threshold, maybe it's a good time to stock up on maintenance medications while the copay is still at the lower amount. Talk to the doctor and pharmacist about timing.

When Things Go Wrong: Appeals and Overrides

If your parent's Part D plan denies a claim, they can appeal. Maybe the plan says a medication isn't covered or isn't medically necessary. Your parent's doctor can provide documentation explaining why it is necessary. The appeal process can take time, but denials can be overridden.

If a medication isn't on the formulary, your parent can request a formulary exception. Maybe your parent's doctor has tried other medications in that class, and none work, and this specific medication is medically necessary. The plan has to consider the exception request. Sometimes they approve it.

If your parent hits prior authorization issues—the plan wants to try cheaper alternatives before approving an expensive medication,the doctor can appeal this too. If the patient has already tried the cheaper alternatives and they didn't work, the doctor can document this and ask for approval of the more expensive medication.

The key is not accepting "not covered" as final without asking. The plan will say no. But there are processes to override the no. Your parent's doctor can be an advocate in this process. If the doctor thinks something is medically necessary, they should be willing to fight for it.

Staying on Top of It Year to Year

Part D changes every January first. A plan your parent loved this year might be discontinued. Benefits change. Formularies change. Copays change.

This means every year, usually during the October through December enrollment period, your parent should review their current plan and compare it to other options. Are their medications still covered? Are the copays still reasonable? Are there better plans now?

This sounds tedious. It is. But the alternative is accidentally overpaying or discovering mid-year that a medication your parent needs isn't covered and they have to pay out of pocket. Annual review prevents that.

Set a calendar reminder in October. Have your parent, or you on their behalf, use the Medicare.gov plan finder again. See whether the current plan is still the best option or whether something better exists. It takes an hour. It can save hundreds of dollars.

Your parent's prescriptions are essential to their health. Understanding Part D and doing the annual review is annoying administrative work. But it's work that directly affects your parent's ability to afford the medications they need. It's worth doing right.

How To Help Your Elders is an educational resource. We do not provide medical, legal, or financial advice. The information in this article is general in nature and may not apply to your specific situation. If you are concerned about a loved one's cognitive health or safety, consult with their healthcare provider or contact your local Area Agency on Aging for guidance and support.