- AEP runs October 15 – December 7, 2026, with changes effective January 1, 2027.
- You can join, switch, or drop Part D and Medicare Advantage plans.
- Review your Annual Notice of Change in September — premiums, formularies, and pharmacy networks shift every year.
Every fall, Medicare gives you a once-a-year window to rethink your prescription drug coverage. The Annual Enrollment Period (AEP) runs from October 15 through December 7, 2026, and any change you make takes effect on January 1, 2027.
Even if you love your current plan, this is the one time of year you should shop. Plans change their premiums, deductibles, drug lists, and pharmacy networks every single year — the plan that was cheapest for you in 2026 may not be in 2027.
What you can do during AEP
- Switch from one stand-alone Part D plan (PDP) to another.
- Join a Part D plan for the first time (a late enrollment penalty may apply if you lacked creditable coverage).
- Drop your Part D coverage.
- Switch between Original Medicare and Medicare Advantage, or from one Medicare Advantage plan to another.
Your AEP checklist
1. Read your Annual Notice of Change
By late September, your plan must send an Annual Notice of Change (ANOC) detailing exactly what's different next year: premium, deductible, copays, formulary changes, and pharmacy network updates. Read it — don't file it.
2. List every prescription you take
Write down each drug, dosage, and frequency — including anything new your doctor prescribed this year. A plan that's great for generics can be terrible for one specialty drug.
3. Check the formulary, not just the premium
A $0-premium plan means nothing if your $400/month brand drug isn't on its formulary or sits on a high tier. Look up each of your drugs in the plan's 2027 formulary and note the tier and any restrictions like prior authorization or step therapy.
4. Confirm your pharmacy is still in-network
Preferred pharmacy networks change. If your plan moves your pharmacy to standard (non-preferred) status, your copays can jump even though nothing else changed.
5. Do the full-year math
Add up: (monthly premium × 12) + deductible + estimated copays for your drugs. Compare two or three plans on total annual cost, not premium alone.
6. Enroll by December 7
You can enroll through Medicare.gov, by calling 1-800-MEDICARE, or through the plan directly. December 7 is a hard deadline — miss it and you're generally locked in until next fall (unless you qualify for a Special Enrollment Period).
What if I do nothing?
If you take no action, you'll generally stay in your current plan (if it's still offered) and roll into its 2027 terms automatically. Doing nothing is a choice — just make it an informed one after reading your ANOC.
Bottom line: October 15 – December 7 is your annual chance to make sure your drug coverage still fits your prescriptions and your budget. Fifteen minutes with your drug list and two or three plan comparisons can save hundreds of dollars next year.