If you are Medicare-eligible but still working, you may be enrolled in job-based coverage. This is coverage your employer or union offers to you and your family. Being enrolled in job-based coverage can allow you to delay your Medicare enrollment. However, depending on whether your job-based insurance pays primary or secondary, you might want to consider still enrolling in Original Medicare. For the most part, you should only delay enrollment in Medicare Part B if your job-based insurance is the primary payer (this means your job-based insurance pays first on medical bills).

If you are eligible for Medicare because you are turning 65 and are covered by you or your spouse’s job-based coverage, you have a Special Enrollment Period (SEP) to enroll in Part B up to 8 months after you no longer have the job-based coverage. This means you are no longer required to take Part B during your Initial Enrollment Period (IEP). Remember, you should only delay Medicare Part B enrollment if your job based insurance is the primary insurance.

Job-based insurance is considered to be primary if it the employer has 20 or more employees. Medicare is secondary in this case. Some people choose not to enroll in Medicare Part B because they are satisfied with their current coverage alone and do not want to pay another premium.

Job-based insurance will be considered if it is from an employer with less than 20 employees. In this case, Medicare is primary, and your job-based coverage may provide little to no coverage if you delay enrollment. In this case, do not delay enrolling in Medicare Part B,

Note: The rules are different if you are eligible for Medicare because of a disability or you have ESRD.

To determine if your job-based insurance is primary or secondary, contact the employer’s human resources department. If you plan to delay Part B enrollment and use the SEP later, keep a record of all your health insurance coverage. To access the SEP, you will have to provide proof of your job-based coverage. Evidence can be supplied as:

  • Written notice from your employer or plan
  • Documents showing premiums paid such as W-2, pay stubs, tax returns, or receipts
  • Health insurance cards with the correct effective date

Note: If you are enrolled in COBRA or retiree insurance, there are separate rules for how Medicare works with your plan.