Section 423.40 - Effective dates(a)Initial enrollment period.(1) An enrollment made prior to the month of entitlement to Part A or enrollment in Part B is effective the first day of the month the individual is entitled to or enrolled in Part A or enrolled in Part B.(2) Except as otherwise provided under § 423.34(f) , an enrollment made during or after the month of entitlement to Part A or enrollment in Part B is effective the first day of the calendar month following the month in which the enrollment in Part D is made.(3) If the individual is not eligible to enroll in Part D on the first day of the calendar month following the month in which the election to enroll in Part D is made, the enrollment in Part D is effective the first day of the month the individual is eligible for Part D.(4) In no case is an enrollment in Part D effective before January 1, 2006 or before entitlement to Part A or enrollment Part B.(b)Annual coordinated election periods - (1)General rule. Except as provided under paragraph (b)(2) of this section, for an enrollment or change of enrollment in Part D made during an annual coordinated election period as described in § 423.38(b) , the coverage or change in coverage is effective as of the first day of the following calendar year.(2)Exception for January 1, 2006 through May 15, 2006. Enrollment elections made during the annual coordinated election period between January 1, 2006 and May 15, 2006 are effective the first day of the calendar month following the month in which the enrollment in Part D is made.(c)Special enrollment periods. For an enrollment or change of enrollment in Part D made during a special enrollment period specified in § 423.38(c) , the coverage or change in coverage is effective the first day of the calendar month following the month in which the election is made, unless otherwise noted.(d)PDP enrollment period to coordinate with the MA annual disenrollment period. Through 2018, an enrollment made from January 1 through February 14 by an individual who has disenrolled from an MA plan as described in § 422.62(a)(5) of this chapter will be effective the first day of the month following the month in which the enrollment in the PDP is made.(e)PDP enrollment period to coordinate with the MA open enrollment period. For 2019 and subsequent years, an enrollment made by an individual who elects Original Medicare during the MA open enrollment period as described in § 422.62(a)(3) of this chapter, will be effective the first day of the month following the month in which the election is made.(f)Beneficiary choice of effective date. If a beneficiary is eligible for more than one election period, resulting in more than one possible effective date, the Part D plan sponsor must allow the beneficiary to choose the election period that results in the individual's desired effective date. (1) To determine the beneficiary's choice of election period and effective date, the Part D plan sponsor must attempt to contact the beneficiary and must document its attempts.(2) If the Part D plan sponsor is unable to obtain the beneficiary's desired enrollment effective date, the Part D plan sponsor must assign an election period using the following ranking of election periods:(3) If the Part D plan sponsor is unable to obtain the beneficiary's desired disenrollment effective date, the Part D plan sponsor must assign an election period that results in the earliest disenrollment. 70 FR 4525 , Jan. 28, 2005, as amended at 76 FR 21570 , Apr. 15, 2011; 83 FR 16737 , Apr. 16, 2018; 85 FR 33911 , June 2, 2020 83 FR 16737 , 6/15/2018; 85 FR 33911 , 8/3/2020; 89 FR 30831 , 6/3/2024