Medicare Enrollment Periods Explained

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A Special Enrollment Period may apply

• Special Enrollment Period — 5-star plan
  December 8 – November 30
  If a 5-star Medicare Advantage or Part D plan is offered where you live, you may switch to that plan once during this span. This form cannot see star ratings. Confirm on Medicare.gov.

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• Initial Enrollment Period
  The seven months around the month you first became eligible
  If you already have Medicare, this first window is behind you. A fall change uses Annual Enrollment.
• Initial Coverage Election Period
  When you first could join a Medicare Advantage plan
  If you already have Medicare, a later Advantage change uses Annual Enrollment, Medicare Advantage Open Enrollment, or a Special Enrollment Period.
• General Enrollment Period
  January 1 – March 31, 2026
  If you missed Initial Enrollment and you do not have a Special Enrollment Period, you can sign up for Part A and Part B during these dates. Coverage usually starts the month after you enroll, and a late penalty can apply. These months are also Medicare Advantage Open Enrollment, which is a different window.
• Annual Enrollment (AEP)
  October 15 – December 7, 2026
  If you already have Medicare, this is the yearly window to change Medicare Advantage or Part D for January 1. It is not Medigap Open Enrollment.
• Medicare Advantage Open Enrollment
  January 1 – March 31, 2026
  If you start the year in a Medicare Advantage plan, you may make one change to another Advantage plan or back to Original Medicare (with Part D if you need it).
• Medigap Open Enrollment
  Six months from the month Part B starts, if you are 65 or older
  Enter a Part B start date to see the dates. This is not Annual Enrollment and not the California Birthday Rule. Under 65, the rule is different.
• California Medigap Birthday Rule
  60 days starting on your birthday
  This window is only if you already have a Medicare Supplement in California. It is not a way to leave a Medicare Advantage plan.
• Special Enrollment Period — job coverage
  While the job coverage lasts, and typically 8 months after the job or the coverage ends, whichever is first
  Coverage from a current employer of 20 or more people, including a working spouse, may let you delay Part B. COBRA usually does not extend this window. Part D uses a shorter clock, often two months. Get the proof in writing. This is not a determination.
• Special Enrollment Period — you moved
  Often the month before the move through two months after it
  A move out of your plan’s service area can let you pick a new Medicare Advantage or Part D plan. The exact months depend on when you tell the plan. Confirm the dates for your move.
• Special Enrollment Period — Extra Help or Medi-Cal
  Once a month, if you have Extra Help or Medicaid
  People with Extra Help, Medi-Cal, or a Medicare Savings Program may switch to Original Medicare and a stand-alone Part D plan, or switch stand-alone Part D plans, once a month. This does not let you join a new Medicare Advantage plan. Some people with full Medi-Cal can also join certain integrated Dual Special Needs Plans once a month. A government agency decides whether you qualify. This form does not.
• Special Enrollment Period — your plan is ending
  The dates in the letter from Medicare or the plan
  If your Medicare Advantage or Part D plan is leaving Medicare or leaving your area, the notice gives the window. Do not guess those dates from this form.
• Special Enrollment Period — trial right
  During the first 12 months in a Medicare Advantage plan, in the situations Medicare allows
  In some first-year cases you can drop Medicare Advantage and return to Original Medicare, and you may have a right to buy a Supplement without health questions. There is more than one trial right. Confirm which one fits before you drop a plan.
• Special Enrollment Period — nursing home or other institution
  While you live in a qualifying institution, and for up to two months after you leave
  A move into or out of a nursing home or similar institution can open a window to join or change a plan. The facility has to qualify. Confirm that on Medicare.gov.

This is a sketch of the windows, including Special Enrollment Periods. It is not a decision from Medicare or Social Security. Confirm the one that fits on Medicare.gov or with Social Security.