Every fall, Medicare’s Annual Enrollment Period (AEP) gives you a short window to switch plans, drop coverage you don’t need, or fix a plan that quietly got more expensive. Missing it — or skipping the paperwork that arrives in September — is one of the easiest ways to overpay for Medicare in the coming year. Here’s a practical, step-by-step checklist to make sure you (or a parent or spouse you help with this) aren’t leaving money on the table for 2027 coverage.
1. What Is the Medicare Annual Enrollment Period (AEP)?
The Annual Enrollment Period runs every year from October 15 to December 7. Any changes you make during this window take effect on January 1 of the following year — so for this year’s AEP, changes take effect January 1, 2027.
AEP is often confused with two other Medicare enrollment windows, but they are not the same thing:
- The Medicare Advantage Open Enrollment Period, which runs January 1 to March 31 and is a much narrower one-time-switch window available only to people already enrolled in a Medicare Advantage plan.
- The Medigap open enrollment window, a one-time six-month period tied to when you first enroll in Medicare Part B — not an annual, recurring event.
2. What You’re Allowed to Change During AEP
During the October 15–December 7 window, you can:
- Switch from Original Medicare to a Medicare Advantage plan, or switch back from Medicare Advantage to Original Medicare.
- Switch from one Medicare Advantage plan to another, with or without drug coverage included.
- Join, switch, or drop a standalone Part D prescription drug plan.
If you do nothing at all, your current plan simply renews automatically — but it renews with whatever changes the plan itself made for 2027, which is exactly why step 1 below matters so much.
3. Step 1 — Find and Read Your ANOC Letter
Every September, your Medicare Advantage or Part D plan mails you an Annual Notice of Change (ANOC) letter. It spells out exactly what’s changing for 2027: premium, deductible, copays, the drug formulary, and the provider network.
Losing or ignoring this letter is the single most common reason people get blindsided by a premium hike or discover — often at the pharmacy counter or a doctor’s office — that their plan dropped a medication or provider from its network.
4. Step 2 — Re-Check Your Drug List Every Single Year
Drug formularies and tiers change annually, even if you keep the exact same plan. A medication that was Tier 2 last year can jump to a higher tier — or suddenly require prior authorization — without you doing anything differently.
Use the Medicare Plan Finder tool at Medicare.gov/plan-compare, and enter your actual pharmacy and your current medication list rather than relying on memory or last year’s numbers.
Common Mistake: Assuming “Cheapest Premium” Means “Cheapest Overall”
A plan advertising a $0 monthly premium can still end up costing you more over the full year once you add up copays, deductibles, and out-of-network costs — especially if your specific prescriptions or specialists aren’t well covered by that plan’s network and formulary.
5. Step 3 — Confirm Your Doctors and Pharmacy Are Still In-Network
Provider networks for Medicare Advantage plans can shrink or change from one year to the next. This is a Medicare Advantage-specific risk — if you have Original Medicare with a Medigap supplement, you generally don’t face this network-shrinkage issue, since Original Medicare is accepted by any provider that takes Medicare nationwide.
6. Step 4 — Compare Total Estimated Annual Cost, Not Just the Monthly Premium
The Medicare Plan Finder tool estimates your total yearly cost — premiums plus your typical drug costs — for each available plan, based on your ZIP code and the medication list you enter. This total-cost estimate is far more useful for comparing plans than the premium number alone.
7. Step 5 — Know the Deadline and What Happens If You Miss It
Any changes must be submitted by December 7. After that date, you’re generally locked into whatever plan you have until the next enrollment window opens, except in specific cases where you qualify for a Special Enrollment Period (for example, moving out of your plan’s service area or losing other creditable coverage).
Worked Example: Checking Your Own Total Annual Cost
Here’s how the comparison works in practice. Suppose you’re comparing your current Medicare Advantage plan against a new option using the Plan Finder tool:
| Cost Factor | Current Plan | Alternative Plan |
|---|---|---|
| Monthly premium | $0/month = $0/year | $35/month = $420/year |
| Estimated annual drug costs (your actual medication list) | $2,100/year | $900/year |
| Typical annual copays/deductible exposure | $900/year | $500/year |
| Estimated total annual cost | $3,000/year | $1,820/year |
In this example, the $0-premium plan actually costs about $1,180 more per year than the plan with a $35 monthly premium, once real drug and copay costs are factored in — a difference you’d never spot by comparing premiums alone. This is exactly the kind of comparison the Medicare Plan Finder tool is built to run using your own ZIP code and drug list.
AEP Money-Saving Checklist: Quick Decision Guide
Use this simple checklist to decide what to do before December 7:
- Received your ANOC letter and nothing important changed? You can likely stay on your current plan, but it’s still worth a quick Plan Finder check.
- ANOC shows a premium, deductible, or copay increase? Run a full comparison in Plan Finder before December 7 — don’t assume your current plan is still the best value.
- A medication moved to a higher tier or now needs prior authorization? Compare Part D or Medicare Advantage drug coverage options specifically for that drug.
- Not sure if your doctor is still in-network for 2027? Confirm directly with the plan or your doctor’s office — don’t rely on last year’s network list.
- Want a second opinion or personalized help? Contact your State Health Insurance Assistance Program (SHIP) or call 1-800-MEDICARE — both offer free, unbiased plan comparison help.
Frequently Asked Questions
Can I switch plans more than once during AEP?
Yes. You can make multiple changes during the October 15–December 7 window — the last change you submit by December 7 is the one that actually takes effect on January 1.
Do I need to re-enroll if I want to keep my current plan?
No. If you take no action, your current plan renews automatically. However, you should still review your ANOC letter, since the plan itself may have changed its premium, costs, or coverage for 2027.
Is AEP the same as the Medicare Advantage Open Enrollment Period in January?
No. AEP (October 15–December 7) is open to everyone with Medicare and lets you make the changes described above. The Medicare Advantage Open Enrollment Period (January 1–March 31) is a narrower window available only to people already enrolled in a Medicare Advantage plan, allowing one additional switch.
Where can I get free, unbiased help comparing plans?
Your State Health Insurance Assistance Program (SHIP) offers free, unbiased, one-on-one counseling, and you can also call 1-800-MEDICARE directly for help comparing your options.
The few minutes it takes to read your ANOC letter and run a Plan Finder comparison before December 7 can save you hundreds of dollars over the coming year. Don’t let automatic renewal decide your 2027 Medicare coverage for you.