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 employer plans.

Updated August 17, 2026 · 2 min read

Part D has its own set of enrollment windows, and they do not line up perfectly with the Part B windows. That mismatch is where most penalties come from.

Initial Enrollment Period

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

Enroll in the first three months and coverage begins the first day of your birthday month.

Annual Enrollment, October 15 to December 7

The main window. Join a Part D plan, switch plans, or drop coverage. Changes take effect January 1.

This is when you should be re-checking your drug list against your plan's formulary for the coming year, every year. See reading your ANOC.

The two month window after employer coverage ends

Leaving creditable employer drug coverage gives you two months to enroll in Part D without penalty.

Medicare Advantage Open Enrollment, January 1 to March 31

If you are in an Advantage plan, you can switch to another Advantage plan or return to Original Medicare and pick up a standalone Part D plan at the same time.

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

Special enrollment periods

Certain circumstances open a window any time of year.

• Moving out of your plan's service area
• 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
• Gaining, losing or changing Medicaid or Extra Help eligibility
• Qualifying for a Medicare Savings Program

That last group matters here. Dual eligibles and people with Extra Help get additional opportunities to change plans during the year rather than being locked to October. See Part D with Medicaid.

The 63 day rule

A gap of fewer than 63 consecutive days without creditable coverage does not trigger the penalty. It is a buffer, not a plan. Do not build your timing around the edge of it.

What to do

1. If you are approaching 65, enroll in the first three months of your window.
2. If employer coverage is ending, act in the first month, not the second.
3. Every October, price your actual medications against available plans before December 7.
4. If your Medicaid or Extra Help status changes, ask what window that opens for you rather than waiting.

See all Medicare enrollment windows.