Every year, October 15th marks the start of the most important 53 days in Medicare. The Annual Enrollment Period (AEP) — commonly called Medicare open enrollment — is your chance to switch plans, drop coverage you don’t need, or upgrade to something better. Miss this window, and you’re stuck for another year. Here’s exactly what you need to know for 2025.
- Medicare open enrollment 2025: October 15 – December 7, 2025
- Changes take effect January 1, 2026
- You can switch Medicare Advantage plans, switch Part D drug plans, or move between Original Medicare and Medicare Advantage
- Even if you’re happy with your plan, review it annually — formularies and premiums change every year
- Use Medicare.gov’s Plan Finder tool to compare all available plans in your area
What Is Medicare Open Enrollment?
The Medicare Annual Enrollment Period (AEP) runs every year from October 15 to December 7. During this window, any Medicare beneficiary — regardless of their current plan — can make changes to their coverage. You don’t need a qualifying life event. You don’t need to explain why. You simply choose, and changes begin January 1.
What You CAN Change During Open Enrollment
- Switch from Original Medicare to a Medicare Advantage plan
- Switch from Medicare Advantage back to Original Medicare
- Switch from one Medicare Advantage plan to another
- Join, switch, or drop a Part D prescription drug plan
- Switch from one Part D plan to another
Why You Should Review Your Plan Every Year — Even If You’re Happy
Insurance companies can change their Medicare plans each year: premiums go up, drug formularies shift, networks change, and new benefits get added (or removed). Here’s what commonly changes year to year:
- Drug formularies — Your medication may move to a higher cost tier or be dropped entirely
- Premiums and deductibles — Your $0 premium plan may start charging next year
- Provider networks — Your doctor may no longer be in-network
- Extra benefits — New dental, vision, or fitness perks may be available in competing plans
3 Steps Every Senior Should Take This Open Enrollment
- List your current medications — Check if they’re still covered under your plan’s formulary at the same tier and cost
- Verify your doctors are still in-network — Especially if you have Medicare Advantage; network changes are common
- Use Medicare Plan Finder at medicare.gov — Enter your medications and see every plan’s total estimated annual cost, including premiums + drug costs
Medicare Enrollment Period Calendar
| Period | Dates | What You Can Do |
|---|---|---|
| Annual Enrollment Period (AEP) | Oct 15 – Dec 7 | Switch any Medicare plan; changes effective Jan 1 |
| Medicare Advantage Open Enrollment | Jan 1 – Mar 31 | Switch MA plans or return to Original Medicare once |
| Initial Enrollment Period | 7 months around 65th birthday | First-time enrollment in Medicare |
| Special Enrollment Period | Triggered by qualifying events | Changes due to move, loss of coverage, etc. |
How to Compare Plans for Free
You have several free resources to compare plans during open enrollment:
- Medicare.gov Plan Finder — The official comparison tool; enter your drugs and zip code for personalized results
- 1-800-MEDICARE — Call for free counseling, 24/7
- SHIP (State Health Insurance Assistance Program) — Free, unbiased local counselors in every state; find yours at shiphelp.org
- Licensed Medicare brokers — Work with multiple carriers; no cost to you (they’re paid by insurers)
Frequently Asked Questions
When is Medicare open enrollment 2025?
The 2025 Medicare Annual Enrollment Period runs from October 15 to December 7, 2025. Any changes made during this period take effect January 1, 2026.
Can I change my Medigap plan during open enrollment?
Not the same way. Medigap changes are not part of the AEP. To switch Medigap plans outside your initial 6-month enrollment window, you typically need to pass medical underwriting.
What if I miss Medicare open enrollment?
If you miss the AEP, you’re generally locked into your current coverage until the next AEP. However, certain qualifying life events (moving, losing other coverage) may trigger a Special Enrollment Period.
Bottom Line
Medicare open enrollment is not just a formality — it’s your annual opportunity to save money and make sure your coverage still fits your health needs. Block out time between October 15 and December 7 to review your plan. Even 30 minutes of comparison shopping can save you hundreds of dollars in 2026.