Medicare Open Enrollment: How to Compare Plans on Total Cost
Published October 22, 2026 路 7 min read 路 Figures last verified October 22, 2026
Reviewed by D.P., PharmD.
- Medicare Open Enrollment runs October 15 to December 7 every year. Changes take effect January 1, and the plan must receive your request by December 7.
- Compare plans on total yearly cost: the monthly premium times 12, plus the deductible, plus what your drugs cost at your pharmacy, plus your doctor-visit copays. Never the monthly premium alone.
- Your plan's prices and drug list change every year even if you do nothing: premiums, deductibles, covered drugs, and pharmacy networks are all renegotiated annually.
- Medicare's free Plan Compare tool estimates each plan's total yearly cost using your actual drug list. That number is the one to sort by.
- If you are happy with your current plan, you do not have to switch. But roughly 7 in 10 beneficiaries didn't compare plans during a recent open enrollment, per KFF, and plans change around them anyway.
In this guide: what you can change 路 the premium trap 路 the four inputs 路 what changed for 2027 路 read this letter first 路 compare in one sitting 路 free help
- Annual Enrollment Period (AEP): October 15 to December 7. You can join, switch, or drop Medicare Advantage and Part D plans. The plan must receive your request by December 7, and changes take effect January 1.
- Medicare Advantage Open Enrollment: January 1 to March 31. Already in a Medicare Advantage plan? You can switch to a different Advantage plan or back to Original Medicare once.
- General Enrollment Period: January 1 to March 31. Missed your initial window for Parts A and B? You can still sign up here; coverage starts July 1.
It is the third week of October. The letter from your plan is on the counter, same logo as last year, and a television ad is promising a $0 premium from somebody else. You did nothing last fall and nothing changed. Here is the trap: nothing changed for you, but the plan's prices and drug list changed behind you. This guide shows how to compare what each plan actually costs you, not what it advertises.
What you can change this fall
Open Enrollment is for people who already have Medicare. During the window, Medicare.gov says you can:
- Join, switch, or drop a Medicare Advantage plan.
- Join, switch, or drop a Medicare drug plan (Part D), if you have Original Medicare.
- Switch between Original Medicare and Medicare Advantage.
- Add or drop drug coverage.
If you make more than one change during the window, the last request before the December 7 deadline is the one that counts. And the reassuring part: Medicare's own materials say that if you reviewed your options and you are happy with your current coverage, you do not need to do anything. Your coverage continues automatically. Open Enrollment is a chance to check, not a requirement to switch.
The premium is the price tag, not the price
The single most expensive Medicare shopping mistake is picking a plan by its monthly premium. The premium is the most visible number, so it feels like the price. It isn't. Your actual yearly cost looks like this:
Premium 脳 12 + annual deductible + drug copays or coinsurance + doctor-visit copays + any out-of-network costs.
A plan with a $0 monthly premium and a $700 drug deductible can cost a person with three daily prescriptions more over the year than a $40-per-month plan with no deductible and low copays. (That is an illustration, not real plan quotes. Your numbers come from Plan Compare, below.) A high premium can buy lower copays; a low premium usually means you pay more at the counter. There is no way to know which side wins without running your own numbers.
Two more traps hiding inside the premium number. First, a "$0 premium" Medicare Advantage plan still requires you to pay the Part B premium (the one that comes out of your Social Security check for most people). "$0" means the plan charges nothing extra, not that Medicare is free. Second, a plan's drug deductible usually applies only to certain tiers. Many plans cover generic drugs before the deductible and apply it only to brand or specialty tiers, so the same $700 deductible bites differently depending on what you take.
The four inputs that decide your total
Every comparison boils down to four things. Get these right and the tool does the rest.
1. Your actual drug list
Not a rough idea of it: the exact drugs, doses, and how often you take them. Plans price each drug by tier, and tiers are where the money goes. A drug moving from tier 1 to tier 3 can turn a $10 copay into a percentage of the full price, which is why our guide to why copays go up starts with tier changes. Check each drug's tier in each plan you consider, not just whether the plan "covers" it. Ask your pharmacy to print your current medication list; that printout is your working document for the whole process.
2. Your pharmacy
The same plan charges different prices at different pharmacies. Most plans have preferred pharmacies with lower cost sharing and standard pharmacies with higher cost sharing, and mail order often costs less than either for a 90-day supply. If the pharmacy you actually use is a plan's standard pharmacy, your real cost is the standard number, not the preferred one.
3. Your doctors (for Medicare Advantage)
On Original Medicare you can see any doctor who accepts Medicare. Medicare Advantage plans use networks: out-of-network care usually costs you more, and sometimes is not covered at all. A plan that looks cheap on paper stops looking cheap if two of your doctors are out of network. Confirm the doctors you see are in the plan before you compare prices.
4. The plan's rules on each drug
Being covered is not the same as being easy to get. Plans can attach prior authorization, step therapy, or quantity limits to individual drugs. If your drug needs prior authorization in the new plan and your doctor's office is slow to file the paperwork, you can have a gap in refills in January. Check the fine print on your specific drugs, not the plan's marketing summary.
What changed for 2027
Plan shopping happens against national numbers that reset each year. For 2027, CMS finalized these in the April 2026 rate announcement:
| Part D figure | 2026 | 2027 |
|---|---|---|
| Maximum annual deductible | $615 | $700 |
| Annual out-of-pocket cap (covered drugs) | $2,100 | $2,400 |
| After the cap | $0 for covered drugs | $0 for covered drugs |
Remember that these are the ceilings for the standard benefit. No plan may charge a deductible above $700, but many plans charge less or waive it for certain tiers. And the cap covers covered Part D drugs only; your premiums and any non-covered drugs sit outside it.
Read this letter first
If you are in a Medicare Advantage or drug plan, your plan mails you an Annual Notice of Change each fall, a few weeks before the window opens. It is the one document that tells you whether what you have in December is what you will have in January. It lists next year's premium, deductible, formulary changes, pharmacy network changes, and new prior-authorization or step-therapy rules.
Most of these letters go straight into the recycling pile with the grocery flyers. Keep yours. If it says your drug moved to a higher tier or left the formulary entirely, that is your prompt to run a comparison. If it says your plan is ending, you will get a separate notice; do not assume you will be automatically moved into similar coverage.
How to compare in one sitting
Medicare's official Plan Compare tool at medicare.gov takes your drugs and your pharmacy and shows each plan's estimated total yearly cost, not just the premium. The site never builds its own estimator, the official tool has the current numbers, so this is the step-by-step way to use it:
- Get your drug list printout from your pharmacy: drug names, strengths, and how often you take each.
- Open medicare.gov/plan-compare and enter your ZIP code.
- Enter your drugs exactly as listed, then select the pharmacy you actually use.
- Sort the results by total yearly cost, not monthly premium.
- For each plan at the top of the list, open the drug details: check the tier, and whether prior authorization, step therapy, or quantity limits apply to your drugs.
- For Medicare Advantage plans, confirm your doctors are in the network before you trust the number.
A free Medicare.gov account saves your drug list and up to five pharmacies from year to year, so next October this takes minutes instead of an afternoon. (A companion guide on getting your drug list ready is coming next in this series.)
Free help that is actually free
Comparing plans alone is fine, but you do not have to. Every state has a State Health Insurance Assistance Program (SHIP) with trained counselors who give free, unbiased Medicare counseling and do not sell anything. You can also call 1-800-MEDICARE (1-800-633-4227) any time. KFF found that plans change premiums, cost sharing, covered drugs, and networks from year to year, and CMS recommends reviewing your options annually; the counselors above exist for exactly that review.
This guide explains how Medicare plan costs and enrollment windows work. It doesn't recommend any plan, doesn't advise which coverage to choose, and doesn't advise starting, stopping, or switching any medication. Those decisions belong to you, your doctor, and your pharmacist. For personal guidance, use Medicare Plan Compare or contact your local SHIP program. Full disclaimer.
Sources
- Centers for Medicare & Medicaid Services, CMS Finalizes 2027 Medicare Advantage and Part D Payment Policies (April 6, 2026; 2027 Part D deductible and out-of-pocket figures from the CY 2027 Rate Announcement)
- Centers for Medicare & Medicaid Services, Final CY 2026 Part D Redesign Program Instructions (2026 baseline: $615 deductible, $2,100 out-of-pocket cap)
- KFF, Few Medicare Beneficiaries Compare Plans or Switch (29% compared plans; 1 in 10 in MA-PD plans voluntarily switched; plans change premiums, cost sharing, and networks year to year)
- Medicare.gov, Medicare Plan Compare (official plan and drug-cost comparison tool; open enrollment October 15 to December 7, changes effective January 1)