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AHIP PHIAS study materials
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AHIP PHIAS: Medicare and Medicare Advantage: Eligibility, Parts, and Enrollment Rules

AHIP PHIAS · Work through your exam, one topic at a time.

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Medicare and Medicare Advantage: Eligibility, Parts, and Enrollment Rules

Structure of the program

Original Medicare = Part A (hospital insurance, usually premium-free with 40 quarters of work) plus Part B (medical insurance, income-related premium, generally optional but needed to enroll in Medicare Advantage). Part C (Medicare Advantage) contracts with CMS to deliver Part A and B benefits, often including Part D, and must provide an out-of-pocket maximum and at least the actuarial value of Original Medicare. Part D covers outpatient prescription drugs through standalone PDPs or MA-PDs. Medigap (Medicare Supplement) is sold by private insurers to fill Original Medicare cost-sharing and does not work with Medicare Advantage.

Enrollment and timing

Know the Initial Enrollment Period (seven months around the 65th birthday month, or the disability/ESRD-based window), the General Enrollment Period (January 1–March 31, with coverage starting the following month), and the Annual Enrollment Period (October 15–December 7, with changes effective January 1). The Medicare Advantage Open Enrollment Period runs January 1–March 31 for a one-time change among MA plans or back to Original Medicare. Special Enrollment Periods arise from employer coverage, moves, and dual-eligible status. Late enrollment in Part B or D can trigger late enrollment penalties based on months without creditable coverage.

Traps to expect

  • Assuming Medigap can be used with Medicare Advantage - it cannot.
  • Confusing the MA Open Enrollment Period with the Annual Enrollment Period, or misstating effective dates.
  • Forgetting that MA plans may use networks and prior authorization even though they must cover the same benefits.
  • Mixing up creditable coverage notices for Part D with Medigap guaranteed-issue rights.

Rule of thumb

If the question asks when a beneficiary can switch from one MA plan to another with a January 1 effective date, the answer is the Annual Enrollment Period; if the change is a single MA-to-MA or MA-to-Original-Medicare move mid-winter, it is the MA Open Enrollment Period.