Yes. You are permitted to disenroll from your Medicare Part D plan or Medicare Advantage plan during the Annual Open Enrollment Period (AEP) -- October 15th through December 7th -- or outside the AEP using a Special Enrollment Period (SEP) if you have alternative creditable prescription drug coverage such as the coverage provided through the VA or TRICARE.

However, as an alternative, you may wish to consider joining a low-cost Medicare Part D prescription drug plan (PDP) or Medicare Advantage plan that includes drug coverage (MAPD).

If you pay a small (or $0) monthly premium for the Medicare plan, you will have access to additional pharmaceutical or healthcare coverage that can work together to complement your VA or TRICARE coverage - coverage that is available just in case your healthcare needs change outside of the annual Open Enrollment Period (AEP).

Starting in plan year 2025, the references for Medicare Part C (Medicare Advantage) and Part D enrollment and disenrollment guidance are combined into one guidance document (see sections below for plan year 2024 and prior year references.)

As reference for the 2025 Medicare Part D plan Special Enrollment Periods, please see:

Medicare Advantage and Part D Enrollment and Disenrollment Guidance, Section 30.6 – Special Election Periods (SEPs)

CMS states,

"Special election periods (SEPs) are election periods outside of the Part D IEP, ICEP, AEP, OEPI, or MA OEP, when an individual may elect a plan or change their current election [Medicare plan]. The effective date of an election [enrollment or disenrollment] made during an SEP is the first day of the month following the month in which the election is made, unless otherwise noted that the effective date may be retroactive or prospective past the following month. Coverage effective dates are always in whole calendar month increments; both retroactive and prospective effective dates are always the first of the calendar month."

One such Special Enrollment Period is:

Section 30.6.19 – SEP for individuals who disenroll from Part D to enroll in or maintain other creditable coverage

CMS states,

"This SEP allows an individual who is enrolled in a Part D plan to disenroll from that Part D plan to enroll in or maintain other creditable prescription drug coverage (e.g., TRICARE or VA coverage). An individual using this SEP to disenroll from an MA-PD plan may also use the SEP to elect Original Medicare or enroll in an MA-only plan. This SEP begins upon the individual’s disenrollment from the Part D plan and ends the first day of the month following the month in which a disenrollment request is received by the plan."

(source: https://www.cms.gov/ files/document/ cy2025cdenrollmentand disenrollmentguidancepdf.pdf)


As reference for the 2024 Medicare Part D plan Special Enrollment Period, please see:

Medicare Manual, Section 30.3.8 - SEPs for Exceptional Conditions

"CMS has the legal authority to establish SEPs when an individual or group of individuals meets exceptional conditions specified by CMS, including on a case-by-case basis. The SEPs CMS has established include: ...

11. SEP for Disenrollment from Part D to Enroll in or Maintain Other Creditable Coverage - Individuals may disenroll from a Part D plan (including PDPs and MA-PDs) to enroll in or maintain other creditable drug coverage (such as TRICARE or VA coverage). The effective date of disenrollment is the first day of the month following the month a disenrollment request is received by the Part D plan." [emphasis added]

Medicare Prescription Drug Benefit Manual, Chapter 3 - Eligibility, Enrollment and Disenrollment
Updated: August 19, 2011 (Revised: November 16, 2011, August 7, 2012, August 30, 2013, August 30, 2014, July 6, 2015, September 1, 2015, September 14, 2015, December 30, 2015, May 27, 2016, August 25, 2016, June 15, 2017, July 31, 2018 & August 12, 2020)

(source: https://www.cms.gov/ Medicare/ Eligibility-and-Enrollment/ MedicarePresDrugEligEnrol/ Downloads/ CY_2017_PDP_Enrollment_and_ Disenrollment_Guidance_8-25-2016.pdf)

As reference for the 2024 Medicare Advantage plan Special Enrollment Period, please see:

The Medicare Manual for Exceptional Condition SEPs:

"CMS has the legal authority to establish SEPs when an individual or group of individuals meets exceptional conditions specified by CMS, including on a case-by-case basis. The SEPs CMS has established include: ...

SEP for Disenrollment from Part D to Enroll in or Maintain Other Creditable Coverage [42 CFR 423.38(c)(18) -]
Individuals may disenroll from a Part D plan (including PDPs and MA-PDs) to enroll in or maintain other creditable drug coverage (such as TriCare or VA coverage). The effective date of disenrollment is the first day of the month following the month a disenrollment request is received by the Part D plan. Additionally, individuals enrolled in an MA-PD plan who have or are enrolling in other creditable coverage may use this SEP to disenroll from the MA-PD plan by enrolling in an MA-only plan." [emphasis added]

Sources include:
Medicare Managed Care Manual, Chapter 2 - Medicare Advantage Enrollment and Disenrollment
Updated: August 19, 2011 (Revised: August 15, 2023)