Medicare Open Enrollment for 2027: A Step-by-Step Checklist
Every fall, people with Medicare get a chance to change their coverage for the next year during the Annual Enrollment Period (AEP), which runs October 15 to December 7. Changes take effect on January 1. Plans can change their premiums, drug lists, networks and extra benefits every year, so the plan you chose last year may not be the best one now. This checklist covers how to review, compare and decide.
Who this is for
The AEP applies to people already enrolled in Medicare who want to switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, or join, drop or change a Part D prescription drug plan. If you are turning 65, you have a separate Initial Enrollment Period around your birthday (seven months, starting three months before the month you turn 65), which is different from AEP. If you are not yet on Medicare and are still on an employer plan, read the section below on delaying.
Step 1: Read what your plan sent you
Every plan has to send an Annual Notice of Change (ANOC) and Evidence of Coverage by the end of September. Look for changes to premiums, deductibles, copays, the drug formulary and the provider network. If you did not receive them, ask your plan or look them up on its website. Do this even if you are happy with the plan, as an unnoticed change is the most common reason for later regret.
Step 2: Check your drugs, doctors and pharmacies
For each prescription, check the formulary tier and any restrictions such as prior authorization or step therapy. In a Medicare Advantage plan, check that your doctors, hospital and specialists are in the network, since out-of-network care may cost more or not be covered. For a Part D plan, check whether your pharmacy is a “preferred” one, since the same drug may cost less there.
Step 3: Use Medicare Plan Finder
Medicare’s Plan Finder at Medicare.gov lets you enter your drugs and your pharmacy and compare plans in your ZIP code by total estimated yearly cost, including premium and drug costs. It also shows star ratings from 1 to 5. If you want help, a State Health Insurance Assistance Program (SHIP) provides free, unbiased counseling, and 1-800-MEDICARE can answer questions. Use these in preference to unsolicited calls or mailings from brokers, who may be paid by a plan.
Step 4: Understand the Part D cap
Since the Inflation Reduction Act changes took effect, Part D has an annual cap on out-of-pocket drug costs. In 2026, the cap is $2,100. After you reach it, you pay nothing for covered drugs for the rest of the year. The cap is indexed, so the number for 2027 is set by CMS; check Plan Finder or your plan’s notice for the 2027 amount. The Medicare Prescription Payment Plan also lets you spread your drug costs over the year in monthly installments rather than paying at the pharmacy counter, which is helpful if you take expensive drugs. It does not lower the total you owe.
Step 5: Compare Original Medicare plus Medigap with Medicare Advantage
| Original Medicare + Part D (+ Medigap) | Medicare Advantage (Part C) | |
|---|---|---|
| Doctors | Any provider that accepts Medicare | Plan network, usually HMO or PPO |
| Premium | Part B premium + Part D + Medigap | Part B premium + plan premium (often $0) |
| Out-of-pocket limit | None in Original; Medigap covers much of it | Yes, annual maximum for in-network services |
| Extras | Not included | Often dental, vision, hearing |
| Prior authorization | Rarely | More often |
| Switching later | Medigap may require medical underwriting | Annual changes allowed in AEP |
The big caveat is Medigap. In most states, once your initial Medigap guaranteed-issue window has passed, an insurer can use medical underwriting to deny you or charge more if you want to switch from Medicare Advantage back to Original Medicare with a Medigap plan. That means that a decision to leave Original Medicare is not always easily reversed. A few states have more generous rules. Learn the rules of your state before you switch.
Step 6: Think about the Medicare Advantage Open Enrollment Period
If you are in a Medicare Advantage plan on January 1 and find it is not working, you have another chance from January 1 to March 31. You can switch to another Medicare Advantage plan or go back to Original Medicare (and join a Part D plan), but you cannot join a Medicare Advantage plan from Original Medicare in this period, or add Part D.
Step 7: Avoid the late penalties
If you are eligible for Medicare but go without Part D or other “creditable” drug coverage for 63 days or more, you may owe a permanent late enrollment penalty of 1% of the national base beneficiary premium for each month you were without it. Similar penalties apply to Part B if you delay without having employer coverage based on current employment. If you are still working past 65 and have an employer plan, ask HR whether it is creditable and whether you should enroll in Part B.
If you have an HSA
Once you are enrolled in any part of Medicare, you can no longer contribute to an HSA. Because Part A can be backdated up to six months when you apply after age 65, stop contributing at least six months before you apply for Medicare or Social Security benefits. You may still use the money in your HSA for qualified costs, including Medicare premiums other than Medigap.
Step 8: Decide and confirm
Enroll in the plan you want before December 7. If you are staying in your current plan, you do not need to do anything, but do check the notice. After you enroll, keep your confirmation, and in January, check that your new card has arrived and that the pharmacy and doctors have it. If you see a problem in January, that is the time to use the Medicare Advantage open enrollment period.
Summary checklist
- Read the ANOC and EOC.
- List drugs and pharmacy; check formulary and tiers.
- Confirm doctors and hospitals are in network.
- Run Plan Finder for all available plans.
- Compare total yearly cost, not just premium.
- Know the Medigap rules before leaving Original Medicare.
- Decide by December 7.
Questions to ask a counselor
If you meet with a SHIP counselor or a broker, bring a list of your drugs with doses, your doctors, your current plan notice and your Medicare card. Ask: Which plans include my doctors and hospital? What is the total estimated cost for the year, including my drugs? What is the plan’s out-of-pocket maximum? Does it require prior authorization for services I am likely to use? How does the plan handle care when I travel? What are the star ratings? If you are considering a switch from Medicare Advantage to Original Medicare, ask what Medigap options are available to you and whether you would need to go through medical underwriting. Decide for yourself; the plan that is best for a friend may not be best for you.