The wrong Part D plan can cost you hundreds — even thousands — more per year than the right one. Here's exactly how to find the plan that covers YOUR medications at the lowest cost.
There are dozens of Part D plans in every area, and they're all different. Different premiums, different deductibles, different drug lists (formularies), different pharmacies, and different copays. The plan that's cheapest for your neighbor could be the most expensive for you — because it all depends on which specific medications you take.
Every year, plans change their formularies, copay tiers, and pharmacy networks. The plan that was best last year might not be best this year. That's why you should review your Part D plan every fall during Open Enrollment (Oct 15–Dec 7).
I cannot stress this enough: do not auto-renew your Part D plan without checking. CMS data shows that people who compare plans annually save an average of $500+/year compared to those who just let their plan roll over. Your drugs, the plan's formulary, and the pricing all change every January. Fifteen minutes on Medicare Plan Finder could save you real money.
Monthly Premium: Varies by plan (national average ~$40/month; some as low as $0 with Extra Help)
Annual Deductible: Up to $590 (many plans have $0 deductible for preferred generics)
Initial Coverage Phase: You pay copays/coinsurance until combined drug costs reach $2,100
Catastrophic Coverage: After $2,100 in total out-of-pocket costs, you pay $0 for the rest of the year (new in 2025 under the Inflation Reduction Act)
Thanks to the Inflation Reduction Act, starting in 2025, your total out-of-pocket Part D drug costs are capped at $2,100 per year. After that, you pay nothing. This is a game-changer for people on expensive medications. Before 2025, there was no cap — costs could spiral into the thousands.
If you hit a high drug cost early in the year, you can now spread your out-of-pocket costs across the entire year in equal monthly payments — interest-free. This is called the Medicare Prescription Payment Plan. Ask your Part D plan about it.
Write down every medication you take: the drug name, dosage, and how often you take it. Include brand-name and generic versions. This is your shopping list.
Which pharmacy do you prefer? In-network pharmacies have lower copays. Many plans offer even lower prices through preferred pharmacies or mail-order. Check if your pharmacy is in the plan's network before enrolling.
Go to Medicare.gov/plan-compare. Enter your drugs, dosages, pharmacy, and ZIP code. The tool will rank every plan by YOUR estimated annual cost — not just the premium. This is the gold standard for comparison.
A $0 premium plan with high copays on your drugs can cost more than a $40/month plan with $0 copays on your drugs. Always compare total estimated annual cost — not just the monthly premium.
Plans rank drugs in tiers (Tier 1 = cheapest, Tier 4–5 = most expensive). If your drug is on a high tier in one plan but a low tier in another, the cost difference can be massive.
Here's the pro move: after Medicare Plan Finder gives you results, look at the top 3 plans by total annual cost — not just #1. Sometimes plan #2 or #3 has a better pharmacy network or covers a drug that #1 restricts. And always check for 'prior authorization' or 'step therapy' requirements on your drugs — those can delay access to your medication even if it's technically on the formulary.
Comparing Part D plans across formularies, pharmacies, and copay tiers is tedious. Chapter's licensed advisors do this every day — they'll enter your drugs, check your pharmacy, and find the plan that saves you the most. Free, no obligation.
Chapter's advisors are licensed, independent, and don't charge you anything — they're paid by insurance companies, not by you.
If your income is below $2,015/month (individual) or $2,725/month (couple) in 2026, you may qualify for Extra Help — a federal program that eliminates your Part D premium, deductible, and drops copays to $5.10 or less for generics. Estimated value: $5,700/year.
If you have Medicaid, SSI, or a Medicare Savings Program, you get Extra Help automatically. Otherwise, apply through Social Security at ssa.gov/medicare/part-d-extra-help.
See our full Extra Help guide for eligibility details and how to apply.
1. Not enrolling when first eligible. If you don't sign up during your IEP and don't have creditable drug coverage, you'll pay a late enrollment penalty — 1% of the national base premium ($36.78 in 2026) for every month you were without coverage. That penalty is permanent.
2. Assuming all plans cover your drugs. Formularies change every year. A drug covered last year might be dropped, moved to a higher tier, or require prior authorization this year.
3. Not checking pharmacy networks. Using an out-of-network pharmacy means higher copays or no coverage at all. Always verify your pharmacy is in-network.
4. Ignoring mail-order options. Many plans offer 90-day mail-order supplies at significantly lower copays than 30-day retail fills. For maintenance medications, this can save hundreds per year.
5. Auto-renewing without comparing. Plans change every January. If you don't compare during AEP (Oct 15–Dec 7), you could be stuck overpaying for 12 months.
A printable worksheet to list your drugs, dosages, and pharmacy — plus a step-by-step Medicare Plan Finder walkthrough.
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