How does Original Medicare work?

You don’t automatically get Medicare when you become eligible. You must enroll in Medicare.

You can enroll in Medicare during the Initial Enrollment Period (IEP) that begins three months before the month you turn 65 and ends three months after the month you turn 65. Most people will be automatically enrolled in Part A, but there are certain situations where you may need to manually enroll in Medicare Part A and/or Part B during your IEP. In order to avoid paying late fees, it is important that you sign up before you turn 65. This applies whether you retire at age 65 or you are enrolled in a Covered California plan.

If you’re enrolled in a Covered California plan, you could save almost $1,500 per month in plan premiums by switching to a Blue Shield Medicare Advantage Plan. That’s nearly $18,000 per year.*

How to apply

To apply, call or visit your local Social Security office or call Social Security at (800) 772-1213, 8 a.m. to 7 p.m., Monday through Friday. TTY users should call (800) 325-0778.

If you have health insurance through your employer or your spouse’s employer, look at your options before signing up for Part B. Please note that Part B has a monthly premium. Ask your benefits administrator or human resources representative for help in choosing the right option for you. Or call Blue Shield of California toll free at (855) 203-3874. We’re here to help.

How to enroll in Medicare beyond the Initial Enrollment Period

Things to know about the Medicare General Enrollment Period: 

  • You might be charged a penalty fee for failing to enroll during your Initial Enrollment Period (IEP).
  • If you did not enroll during the IEP when you were first eligible, you may enroll during the General Enrollment Period.
  • The General Enrollment Period for Original Medicare (Medicare Parts A and B) occurs each year from January 1 through March 31.

Things to know about the Medicare Special Enrollment Period (SEP)

You are granted a Special Enrollment Period, outside the Initial Enrollment Period (IEP) and Annual Enrollment Period, if you have group, employer, or union coverage:

  • When you turn 65, you may choose to forgo Medicare Part B when you become eligible. You will be able to enroll in Medicare when your group coverage ends.
  • Your eight-month SEP for Medicare Part B begins either the month that your employment ends or immediately when your group health coverage ends.
  • If you enroll in Medicare during an SEP, you do not have to pay a late-enrollment penalty.

Other Medicare enrollment options:

  • You are collecting Railroad Retirement Board or Social Security retirement benefits. Read more.
  • You are receiving disability benefits. Read more.
  • You have amyotrophic lateral sclerosis (ALS). Read more.
  • You have end-stage renal disease (ESRD). Read more.


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*Actual savings may vary. Savings are based on statewide averages of the monthly rate table in 2024 for Blue Shield Individual & Family Plan PPO members over the age of 65 and a $0 plan premium Medicare Advantage Plan. Monthly plan rates can depend on your plan, age, and where you live.

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Page last updated: 01/01/2024

*Free copy with no obligation to enroll.

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For Blue Shield Medicare Advantage Plans: Blue Shield of California is an HMO, HMO D-SNP, PPO and a PDP plan with a Medicare contract and a contract with the California State Medicaid Program. Enrollment in Blue Shield of California depends on contract renewal.

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