Blog / Part D

When can I enroll in or change my Part D plan?

Every window for joining, switching or dropping drug coverage, and the two month deadline that catches people leaving an employer plan.

Updated September 3, 2026 · 3 min read · by Gerino Alejos

You can first sign up for Part D, the part of Medicare that pays for prescription drugs, during the same seven month window as the rest of Medicare. After that, the main chance to join or switch is Annual Enrollment, October 15 to December 7, with the change taking effect January 1. Leaving employer coverage opens its own two month window.

These windows do not line up with the Part B windows. That mismatch is where most penalties start, and the penalty is an extra amount added to your monthly drug bill for good.

Initial Enrollment Period

The same seven months as the rest of Medicare. Three months before your birthday month, the birthday month itself, and the three months after.

Sign up in the first three months and your coverage starts the first day of your birthday month. See how to sign up for the first time.

Annual Enrollment, October 15 to December 7

This is the main window. You can join a Part D plan, switch plans, or drop coverage. What you change takes effect January 1.

Use it to check your drug list against your plan's formulary, the list of drugs the plan pays for next year. Do that every year. See reading your Annual Notice of Change.

The two month window after employer coverage ends

Creditable coverage means drug coverage that is at least as good as Part D. When you leave a creditable employer plan, you have two months to enroll in Part D without a penalty.

Medicare Advantage Open Enrollment, January 1 to March 31

A Medicare Advantage plan is a private plan that covers your Medicare benefits. If you are in one, you can switch to another Advantage plan during this window. You can also drop back to Original Medicare and pick up a standalone Part D plan, a drug plan you buy on its own.

You cannot use this window to move from one standalone Part D plan to another. See how that window works.

Special enrollment periods

Some events open a special enrollment period, a window to change plans at other times of the year.

• Moving out of your plan's service area, the counties it is sold in.
• Losing creditable drug coverage through no fault of your own.
• Your plan leaving the area, or losing its Medicare contract.
• Moving into or out of a skilled nursing facility, a nursing home with medical care.
• Gaining, losing or changing Medicaid or Extra Help, the program that pays part of your drug costs if your income is low.
• Qualifying for a Medicare Savings Program, a state program that helps pay your Medicare costs.

That last group matters most here. People who have both Medicare and Medicaid, and people with Extra Help, get added chances to change plans during the year rather than waiting for October. See Part D with Medicaid.

The 63 day rule

A gap of fewer than 63 days in a row without creditable coverage does not trigger the penalty. Treat that as a small cushion, not something to aim for.

What to do next

1. If you are close to 65, sign up in the first three months of your seven month window.
2. If employer coverage is ending, act in the first month, not the second.
3. Every October, price your own medications against the plans open to you before December 7.
4. If your Medicaid or Extra Help status changes, ask which window that opens for you rather than waiting.

See all Medicare enrollment windows. If you want a second set of eyes on your timing, call our McAllen office at (956) 687 3334, or enter your ZIP code in the plan pricing box on this page.

Gerino Alejos

Licensed insurance agent · License 3128710 · NPN 18243381

Owner of McAllen Insurance Group, an independent agency on North 10th Street in McAllen. Works with clients across Hidalgo, Cameron and Starr counties on Medicare, Marketplace health, life and auto coverage. Se habla español.