Yes.  If you joined your Medicare Advantage plan (MAPD) during your Initial Coverage Election Period (ICEP) (similar to your Medicare Part D Initial Enrollment Period (IEP)) surrounding your 65th birthday - and you are still within the first 12 months of coverage - Medicare provides a Special Enrollment Period (SEP65) so that you can disenroll from your Medicare Advantage  plan, return to Original Medicare, and join a stand-alone Medicare Part D prescription drug plan (or PDP).

As a reminder, a Special Enrollment Period (SEP) allows you to change Medicare plans during the plan year, outside of the annual Open Enrollment Period (AEP) that starts October 15 and continues through December 7 - or the Medicare Advantage Open Enrollment Period (MAOEP) that runs through March 31.  Also remember, an SEP is usually only granted in limited situations such as this.

The Medicare manual notes:

"[Medicare Advantage] eligible individuals who elect an MA plan (other than an MSA plan) during the initial enrollment period (IEP) for Part B surrounding their 65th birthday have an SEP.  This “SEP65” allows the individual to disenroll from this MA plan and elect the Original Medicare plan any time during the 12-month period that begins on the effective date of coverage in the MA plan. The IEP for Part B is established by Medicare and begins 3 months before and ends 3 months after the month of the individual’s 65th birthday.  Individuals entitled to Medicare prior to age 65 are not eligible for the SEP65." [emphasis, formatting, and link added]

Leaving your MAPD and joining a PDP within the first 12 months of enrollment?

If you leave your Medicare Advantage plan that includes drug coverage using the SEP65 Special Enrollment Period, you will be granted an additional SEP to join a stand-alone Medicare Part D drug plan (PDP).  The Medicare manual also includes the following Medicare Part D SEP that coordinate with the Medicare Advantage Special Enrollment Period:

"The following Part D [SEP is] established to coordinate with [SEP65] election periods in the MA program. More information about MA election periods can be found in MA Enrollment and Disenrollment Guidance (MMCM Chapter 2).

A. SEP for MA-PD enrollee using the MA SEP65 - MA eligible individuals who elect an MA plan during the initial coverage election period (ICEP) surrounding their 65th birthday have an SEP called the “SEP65.” The SEP65 allows the individual to disenroll from the MA plan and elect the Original Medicare plan any time during the 12-month period that begins on the effective date of coverage in the MA plan. If the individual using the SEP65 is disenrolling from an MA-PD plan [Medicare Advantage plan that includes prescription drug coverage], he or she may (but is not required to) use this Part D SEP to enroll in a PDP plan. This SEP must be used at the same time the SEP65 is used." [emphasis and formatting added]

How to use your SEP65 and join a PDP?

To take advantage of this SEP,  we would suggest you speak with a Medicare representative about your Medicare plan eligibility and options.  To contact Medicare, please call toll-free 1-800-633-4227, 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 SEP65 situation to a Medicare representative and ask the representative to help you find a Medicare Part D prescription drug plan that most economically covers your medication needs.

References:

Medicare Managed Care Manual, Chapter 2 - Medicare Advantage Enrollment and Disenrollment, Updated: August 19, 2011 (Revised: November 16, 2011, August 7, 2012, August 30, 2013, August 14, 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, & August 15, 2023)

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, & August 15, 2023)