Medicare’s Annual Enrollment Period (also called Medicare Open Enrollment) for 2027 coverage runs October 15 through December 7, 2026 — the yearly window when anyone already on Medicare can join, switch, or drop a Medicare Advantage or Part D prescription drug plan. Whatever you choose takes effect January 1, 2027, and December 7 is a hard deadline with no extensions. This year’s window matters more than most: two separate subsidies that had been holding down costs are both expiring, so even if you’re happy with your current plan, it’s worth checking the new numbers before you let it auto-renew.
2027 Medicare Open Enrollment: Key Dates
| Milestone | Date | What It Means |
|---|---|---|
| Plans publish 2027 details | October 1, 2026 | Carriers release next year’s premiums, benefits, and networks |
| Open enrollment begins | October 15, 2026 | You can start comparing and switching plans |
| Open enrollment ends | December 7, 2026 | Hard deadline — no extensions |
| Coverage changes take effect | January 1, 2027 | New plan choices begin |
| Medicare Advantage Open Enrollment | January 1 - March 31, 2027 | One additional plan change allowed, MA-to-MA or back to Original Medicare |
This Annual Enrollment Period (AEP) is separate from the ACA Marketplace open enrollment (November 1, 2026 - January 15, 2027), which applies to individual/family health insurance, not Medicare. If you’re on Medicare, the AEP dates above are the ones that apply to you.
What You Can Actually Do During This Window
If you already have Medicare Part A and Part B, the Annual Enrollment Period lets you:
- Switch from Original Medicare to a Medicare Advantage plan, or the reverse
- Switch between two different Medicare Advantage plans
- Join, switch, or drop a Part D prescription drug plan
It is not the window for first-time Medicare sign-up — that’s handled by your Initial Enrollment Period (the 7 months around your 65th birthday) or a Special Enrollment Period if you’re delaying Medicare because of employer coverage.
Why This Year’s Enrollment Matters More Than Usual
Two cost-related changes are converging on the 2027 plan year:
- Enhanced ACA premium subsidies expired at the end of 2025 and were not restored by Congress. While that directly affects ACA marketplace plans rather than Medicare itself, it’s part of a broader pattern of subsidies rolling back this year, and it’s pushing more people to scrutinize Medicare costs closely too.
- A separate federal subsidy that had been holding down Medicare Part D drug plan premiums is ending after 2026. That means many Part D (and Medicare Advantage plans with drug coverage) premiums are likely to rise for 2027, even if your plan’s formulary and coverage stay the same.
- CMS released its 2027 premium projections on September 28, 2026, giving beneficiaries an early look before enrollment opened — a signal worth taking seriously rather than assuming your current plan’s price is unchanged.
Because of this, auto-renewing without comparing is riskier this year than in a typical year. A plan that was the cheapest option in 2026 may not be in 2027 once drug-plan subsidies roll off.
How Medicare Premiums Interact With Your Retirement Budget
For most retirees, the standard Part B premium is deducted directly from your Social Security check before it ever hits your bank account — which makes it easy to overlook when you’re budgeting. A few practical steps:
- Check your current premium on your Medicare account or your most recent Social Security benefit statement.
- Compare it to your plan’s 2027 premium once it’s published October 1 — Part D and Medicare Advantage premiums can change year to year even if Part B’s base premium doesn’t.
- Run your expected 2027 net Social Security payment (gross benefit minus Medicare premiums) through the Social Security calculator to see your real take-home number, not just your gross benefit.
- Plug that net number into the budget calculator alongside your other retirement income and expenses to see whether a premium increase changes how much you can safely withdraw elsewhere.
If you’re also drawing from a traditional IRA or 401(k), remember that your Required Minimum Distribution (RMD) is separate from — but adds to — your taxable income for the year, which can affect whether you cross an IRMAA income threshold that raises your Medicare premium even further. Use the RMD calculator to see your required withdrawal for 2026 or 2027 before you decide whether to take more than the minimum.
A Simple Pre-Enrollment Checklist
- Review your Annual Notice of Change (ANOC), which your current plan mails by the end of September — it lists exactly what’s changing in your premium, deductible, and covered drugs for 2027.
- Re-check your prescription list against your plan’s 2027 formulary; drug tiers and covered pharmacies can shift year to year even if you don’t change plans.
- Confirm your doctors are still in-network, especially if you’re on a Medicare Advantage plan, since provider networks can narrow between plan years.
- Compare at least one alternative plan even if you’re satisfied with your current one — a side-by-side comparison takes a few minutes on Medicare.gov and can reveal a lower-cost option with the same coverage.
- Mark December 7 on your calendar a few days early so you’re not racing the hard deadline.
Frequently Asked Questions
What’s the difference between Medicare Open Enrollment and ACA Open Enrollment? Medicare’s Annual Enrollment Period (October 15 - December 7, 2026) is only for people already on Medicare who want to change their Medicare Advantage or Part D plan. ACA Marketplace open enrollment (November 1, 2026 - January 15, 2027) is for individual/family health insurance and doesn’t apply once you’re on Medicare.
What happens if I miss the December 7 deadline? You’ll keep your current Medicare Advantage or Part D plan through 2027. Outside of a Special Enrollment Period (triggered by specific life events) your next chance to change is the Medicare Advantage Open Enrollment Period, January 1 - March 31, 2027, which allows one additional switch.
Will my Medicare premium go up in 2027? The standard Part B premium is set by CMS, typically announced in November. Part D and Medicare Advantage premiums vary by plan and are more directly affected by the expiring drug-plan subsidy — many are expected to rise, which is exactly why comparing your Annual Notice of Change to alternative plans is worth the time this year.
Does my Medicare premium affect my Social Security check? Yes — for most retirees, the Part B premium (and any Part D premium you’ve elected to have withheld) is deducted directly from your monthly Social Security benefit, so your net deposit is lower than your gross benefit amount.
Can switching plans during this window ever raise my costs? It’s possible if you switch into a plan with a higher premium, deductible, or into a different drug tier structure for your medications — which is exactly why comparing total costs (premium + deductible + expected drug costs), not just the headline premium, matters more than picking the cheapest-looking option.
The Bottom Line
Medicare Open Enrollment for 2027 coverage runs October 15 through December 7, 2026, with no extensions on the deadline. Two subsidies rolling off this year — one for Part D drug plans, another in the broader ACA market — make this a worse-than-usual year to simply let your plan auto-renew without comparing. Once you know your 2027 premium, run your expected net Social Security benefit through the Social Security calculator, check how a Required Minimum Distribution might affect your income with the RMD calculator, and confirm it all fits your monthly numbers with the budget calculator — before your December 7 deadline arrives.