Medicare Open Enrollment Explained: What to Review Before December 7
Medicare open enrollment runs October 15 to December 7. Learn what you can change, how Original Medicare and Medicare Advantage differ, and a checklist to avoid costly mistakes.
Every year from October 15 to December 7, people with Medicare can change how they get their coverage for the following year. Plans change their costs, drug lists and networks every year, so a plan that was right last year may not be this year. A short review can save hundreds or thousands of dollars.
What you can do during open enrollment
- Switch from Original Medicare to a Medicare Advantage (Part C) plan, or back
- Switch from one Medicare Advantage plan to another
- Join, switch or drop a Part D prescription drug plan
Changes take effect January 1. If you're happy with your plan, you don't have to do anything; it usually renews automatically.
Original Medicare vs Medicare Advantage
| Original Medicare (Parts A & B) | Medicare Advantage (Part C) | |
|---|---|---|
| Who runs it | The federal government | Private insurers approved by Medicare |
| Doctors | Any provider nationwide that accepts Medicare | Usually a network (HMO or PPO) |
| Drug coverage | Add a separate Part D plan | Usually included |
| Out-of-pocket limit | None, unless you add a Medigap policy | Yearly maximum built in |
| Extras (dental, vision, hearing) | Generally not covered | Often included |
| Prior authorization | Rarely required | Often required for some services |
Medigap warning: if you leave Original Medicare plus Medigap for Medicare Advantage, you may not be able to get a Medigap policy again later without medical underwriting in many states. Think carefully before giving up Medigap.
Your open enrollment checklist
- Read your Annual Notice of Change (ANOC). Plans send it by September 30. It lists next year's changes to premiums, deductibles, copays and the drug list.
- List your medications and doses. Check each one against the plan's formulary (drug list) and tier, and see whether prior authorization is required.
- Confirm your doctors and hospitals are still in network for next year.
- Compare plans on Medicare.gov's Plan Finder. Enter your drugs and pharmacy to see estimated total yearly costs.
- Look at the total, not just the premium. A $0-premium plan can cost more than a plan with a premium once you add deductibles and copays.
- Check for Extra Help. If your income and resources are limited, the Extra Help program can sharply lower drug costs.
Prescription drug costs have a cap
Since 2025, Part D has an annual out-of-pocket cap on covered drugs ($2,000 in 2025, adjusted for inflation afterward). You can also spread drug costs into monthly payments through the Medicare Prescription Payment Plan. If you take expensive medications, these changes can make a big difference when comparing plans.
Part B premiums and your Social Security
Most people pay the Part B premium out of their Social Security check. Social Security benefits rise 3.6% in 2027, but a higher Part B premium will absorb part of that raise. See Social Security COLA 2027. Higher-income beneficiaries pay income-related surcharges (IRMAA) based on their tax return from two years earlier.
Missed the deadline?
- Medicare Advantage Open Enrollment (January 1 – March 31): if you're in a Medicare Advantage plan, you can switch to another Advantage plan or go back to Original Medicare once.
- Special Enrollment Periods apply after certain events, like moving or losing other coverage.
Protect yourself from scams
Medicare won't call you uninvited to sell plans or ask for your Medicare number. Be cautious with TV ads and callers promising "extra benefits." For free, unbiased help, contact your state's SHIP (State Health Insurance Assistance Program).
Key takeaways
- Medicare open enrollment runs October 15 to December 7; changes start January 1.
- Review your Annual Notice of Change, drugs and doctors every year.
- Compare total yearly cost on Medicare.gov's Plan Finder.
- Think carefully before giving up Medigap; you may not get it back.
Sources: Medicare.gov; Centers for Medicare & Medicaid Services.
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