How to Change Part D Plans: Switching Drug Coverage During Open Enrollment

Your parent's pharmacy just told them their copay doubled because the plan moved their blood pressure medication to a higher tier. The Annual Notice of Change confirmed it. Now you need to switch plans — but the mechanics of actually making the change trip up more families than the decision itself.

When You Can Switch

Medicare Part D plan changes happen during specific enrollment windows. The primary one is the Annual Election Period (AEP), which runs October 15 through December 7 every year. Any change made during AEP takes effect January 1.

Outside AEP, you can only switch if your parent qualifies for a Special Enrollment Period — triggered by events like moving to a new ZIP code, losing employer drug coverage, or qualifying for Extra Help.

There's also the Medicare Advantage Open Enrollment Period (January 1 through March 31), but that only applies if your parent is in a Medicare Advantage plan and wants to switch to Original Medicare plus a standalone Part D plan, or switch between MA plans.

How to Actually Make the Switch

Step 1: Run the medication list on Plan Finder. Before changing anything, enter every current prescription into Medicare Plan Finder with the correct dosage, quantity, and pharmacy. Sort by total estimated annual cost — not monthly premium — to find the best match.

Step 2: Enroll in the new plan. You can enroll three ways:

• Online through Medicare.gov's Plan Finder (fastest)
• By calling the new plan's member services directly
• By calling 1-800-MEDICARE (1-800-633-4227)

Step 3: Confirm the enrollment. Print or screenshot the confirmation number, date, and plan name. If your parent enrolls during AEP, the new coverage starts January 1 — their old plan terminates automatically on December 31. You do not need to separately cancel the old plan.

What Happens to Current Prescriptions

This is the part that catches families off guard. When you switch Part D plans, three things reset on January 1:

• The deductible starts over. Even if your parent met the $615 deductible in November, the new plan's deductible applies fresh in January.
• Prior authorizations don't transfer. If the old plan had approved a prior authorization for a medication, the new plan requires its own approval process. Your parent's doctor may need to submit paperwork again.
• Transition supply rules apply. Federal rules require the new plan to provide a one-time 30-day transition supply of medications your parent was currently taking, even if those drugs aren't on the new plan's formulary. This gives you a window to work with the doctor on formulary exceptions or therapeutic alternatives.

Avoiding a Coverage Gap

The biggest risk in switching plans is a pharmacy denial in the first week of January. To prevent it:

1. Refill all current prescriptions in late December under the old plan, so your parent has a 30-day supply to cover any transition delays.
2. Contact the new plan in December to confirm which medications are on the formulary and whether any require prior authorization. Don't wait until January.
3. Keep a copy of the old plan's Evidence of Coverage — if you need to appeal a denial, having documentation of the prior plan's approved medications strengthens the case.

If your parent takes a specialty medication or anything requiring prior authorization, the Medicare Part D: How to Choose a Drug Plan guide includes a transition checklist that tracks each prescription's formulary status, PA requirements, and transition supply eligibility across the old and new plans.

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