Switching Part D plans
Auto-renewing your Part D plan year after year is one of the most expensive default decisions in Medicare. Formularies change every January. We'll walk you through the right way to re-check.
The short version
Re-evaluate your Part D plan every October. Compare your current drug list against next year's formularies, check tier changes, and confirm your pharmacy stays preferred. Switch during AEP (Oct 15 to Dec 7) for a January 1 effective date.
When you can switch
- AEP (Oct 15–Dec 7): the main window for everyone
- OEP (Jan 1–Mar 31): Medicare Advantage enrollees can switch MAPDs or move to Original Medicare + standalone Part D
- SEPs: moving out of plan area, losing creditable coverage, qualifying for Extra Help, plan terminations, and others
- Five-star SEP: once per year, switch to a plan with a 5-star CMS rating (where available)
The Annual Notice of Change (ANOC)
Your plan sends an ANOC every fall, by late September, listing every change effective January 1. It's the single most useful document Medicare produces. Open it and look for:
- Premium change
- Formulary tier changes on the drugs you take
- Drugs removed from the formulary
- New prior authorization or step therapy
- Preferred pharmacy changes
How to compare plans
- List every drug you take, with dosage and quantity
- Pick your preferred pharmacy (mail order, big-box, independent)
- Run the comparison on medicare.gov's Plan Finder with your drug list
- Sort by total estimated annual cost, not by premium alone
- Confirm the plan's network includes your pharmacy at the preferred level
Why total cost matters more than premium
A $0-premium plan can cost more than a $40-premium plan if your drugs are in worse tiers. The total annual cost — premium plus deductible plus copays — is what matters. The Plan Finder calculates this for you when you enter your drug list.
Switching the right way
Enroll in the new plan directly. Disenrollment from the old plan is automatic. Don't call to cancel the old one first — that can create a coverage gap.
If switching from a MAPD to a standalone Part D plan, enrolling in the Part D plan during AEP automatically disenrolls you from Medicare Advantage and returns you to Original Medicare. That's a much bigger move than a Part D switch; do it deliberately.
Frequently asked questions
- When can I switch Part D plans?
- The main window is the Annual Enrollment Period, October 15 to December 7. Coverage starts January 1. You can also switch during the MA Open Enrollment Period if you're on a MAPD, or anytime during a Special Enrollment Period triggered by qualifying events.
- Why would I switch Part D plans?
- Formularies change every January. A drug that's Tier 2 this year could be Tier 4, prior-authorized, or off-formulary next year. Premiums and pharmacy networks also change. Switching when your current plan stops being the best fit can save hundreds per year.
- Will switching Part D affect my Medigap?
- No. Medigap covers Medicare-approved costs under Parts A and B. It doesn't interact with Part D. You can switch Part D plans every year without touching your Medigap policy.
- Can I switch from Part D to a Medicare Advantage plan with drug coverage?
- Yes, during AEP. Enrolling in a MAPD automatically disenrolls you from any standalone Part D plan. If you're on Original Medicare with Medigap, switching to a MAPD also ends your Medigap policy on the date Advantage starts.
- Does the Inflation Reduction Act change how I should pick a Part D plan?
- Yes. With the annual out-of-pocket cap, the formerly catastrophic worst-case is now bounded. That makes formulary tiers and pharmacy network the bigger drivers of which plan is cheapest for you, not raw worst-case math.
Don't auto-renew your Part D plan
Set a calendar reminder for early October. Re-checking takes 15 minutes and saves real money.
Educational resource. Not legal, tax, or insurance advice.