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When to Enroll in Medicare

Deciding when to enroll in Medicare can be one of the most confusing Medicare decisions to make. Sure, its straightforward when you are turning age 65, but what if you are going to continue to work?

In this article we explain exactly when you should enroll in Medicare based on which category you fall into with your Medicare situation.

Starting Medicare Before Age 65

In order to enroll in Medicare before age 65 you have to be disabled. Those beneficiaries will receive Part A immediately and then receive Part B 24 months later. You can read more about Medicare for the Disabled here

Starting Medicare At Age 65

Most people will begin Medicare when they turn 65, but others will continue working and stay on their employer group health insurance.

Not On Employer Group Health Insurance

Congratulations, your enrollment into Medicare is the simplest. Your Initial Enrollment Period (IEP) is a 7-month period that spans 3 months before and after the month you turn age 65. 

Example: Initial Enrollment Period at Age 65

  • Ashley turns age 65 on June 18, 2023
  • The earliest her Medicare can start is the first day of her birth month – June 1st
  • Her IEP begins March 1st (3 months before June 1st)
  • Her IEP ends September 1st (3 months after June 1st)
  • If she enrolls before June 1st (recommended) her start date will be June 1st.
  • If she enrolls June 2nd through the end of her IEP, coverage will start the first of the next month.

Funky Medicare Rule #632
If your birthday is on the 1st of the month, you’ll start Medicare on the 1st of the previous month. Example: Susan turns 65 on June 1st, 2023. Her Medicare starts May 1st.

Continuing to Work

The rules for signing up for Medicare are different based on the size of your employer group health plan:

  • Under 20 employeesMedicare is primary, employer coverage is secondary. You will have to take Medicare Part A and Part B in order for your coverage to work properly.
  • Over 20 employeesEmployer coverage is primary, Medicare is secondary. In most cases it does not make sense to take Medicare if you will be staying on your employer health coverage.

Starting Medicare After Age 65

If you continued to work past age 65, you will need to enroll in Medicare once you retire and lose your employer group health insurance. 

Your Initial Enrollment Period will work just the same as if you had started Medicare at age 65, but instead of your birth month being the start date for Medicare, you will start Medicare when your employer coverage ends. 

Example: Initial Enrollment Period after age 65

  • Elliot is retiring and losing employer coverage on June 30, 2023
  • The earliest his Medicare can start is July 1st.
  • His IEP begins April 1st (3 months before July 1st)
  • His IEP ends October 1st (3 months after July 1st)
  • If he enrolls before July 1st (recommended) his start date will be July 1st.
  • If he enrolls July 2nd through the end of his IEP, coverage will start the first of the next month.


No, as long as you have creditable coverage you will not have a penalty for delaying Medicare Part B.

There is no way to know for sure without doing a Cost Benefit Analysis to compare your options. Line up all your costs, deductibles, and co-pays for your employer plan on one side and do the same for Medicare on the other. Be sure to take into account the *much* smaller deductibles on Medicare when making your decision.

If you don't enroll in Medicare and do not have other creditable coverage, you will have a Medicare Part B penalty added onto your monthly premium if/when you sign up for Part B in the future.


Knowing when to enroll in Medicare can be a confusing situation. The key is to make sure you have “creditable coverage” so that you avoid any unnecessary penalties. Schedule an appointment with us to compare the plans in your area.