Maybe.  However, reinstatement into a Medicare plan after member-initiated disenrollment is only allowed by the Centers for Medicare and Medicaid Services (CMS) in very limited situations.

The Medicare Prescription Drug Benefit Manual (Chapter 3 Eligibility, Enrollment and Disenrollment) notes:

“As stated in [the Medicare manual], deliberate member-initiated disenrollments imply intent to disenroll. Therefore, reinstatements generally will not be allowed if the member deliberately initiated a disenrollment. An exception is made for those members who were automatically disenrolled because they enrolled in another plan but subsequently cancelled the enrollment in the new plan before the effective date.”  [emphasis added]  (Section 60.2.2 - Reinstatements Based on Beneficiary Cancellation of New Enrollment)

And the Section “Disenrollments Not Legally Valid” notes:

“CMS also does not regard a voluntary disenrollment as actually complete if the member or his/her legal representative did not intend to disenroll from the PDP.  If there is evidence that the member did not intend to disenroll from the PDP, the PDP sponsor should submit a reinstatement request to CMS (or its designee).

Evidence that a member did not intend to disenroll may include:

• A disenrollment request signed by the member when a legal representative should be signing for the member; or
  
  
• Request by the member for cancellation of disenrollment before the effective date (refer to §60.1 for procedures for processing cancellations).
  

Discontinuation of payment of premiums does not necessarily indicate that the member has made an informed decision to disenroll.

In contrast, CMS believes that a member’s deliberate attempt to disenroll from a plan (e.g., sending a written request for disenrollment to the PDP sponsor, or calling 1-800-MEDICARE) implies intent to disenroll.

Therefore, unless other factors indicate that this disenrollment is not valid, what appears to be a deliberate, member-initiated disenrollment should be considered valid [and reinstatement will not be allowed].”  [emphasis added]

Therefore, the circumstances surrounding your voluntary disenrollment will probably decide whether your request for reinstatement into your former Medicare plan is accepted.

Using a Special Enrollment Periods after disenrollment

Please note – even if you are not reinstated into your Medicare Part D plan, you may be able to use a Special Enrollment Period to join a Medicare plan starting the next month after enrollment.  See:  What are the Medicare Part D Special Enrollment Periods (SEP)?

For more information about reinstatement after disenrollment and / or using a Special Enrollment Period, you should contact a Medicare representative.

To contact Medicare directly please call toll-free 1-800-633-4227, an automated telephone system will answer, say “no” to any unrelated questions, select the prescription drug option, and then choose the option to speak with a Medicare representative or say "representative" several times during the automated menu options.

Once connected, please explain your situation to a Medicare representative and ask the Medicare representative about reinstatement or a Special Enrollment Period to re-join a Medicare Advantage plan or a Medicare Part D prescription drug plan.

If you are eligible for enrollment, the Medicare representative can also process her enrollment into any Medicare Part D or Medicare Advantage plan directly over the telephone - and the process only takes a few minutes (with an enrollment confirmation code provided - that you should record).

Please note that a Medicare representative is not compensated for a Medicare plan enrollment and provides you with an unbiased view of all available Medicare Part D plans or Medicare Advantage plans.

For further information, please also see our FAQ:  What should I do if I disenrolled from my Medicare Part D plan for next year, but it was a mistake, and I wish to stay enrolled in my plan?

Sources include:

(Medicare Prescription Drug Benefit Manual, Chapter 3 - Eligibility, Enrollment and Disenrollment, Updated: August 19, 2011 (Revised: August 15, 2023)