If you have retiree insurance from your or your spouse’s former employer, in almost all cases, you should enroll in both Medicare Parts A and B to have full coverage of doctors’ services and other medical care. This applies if you are eligible for Medicare because you are 65 or older or you are eligible for Medicare due to a disability. Part A covers inpatient care and Part B covers doctor’s visits and other outpatient care.

Retiree coverage may look the same as the coverage you had when you were currently working, but it generally works differently. Retiree insurance is secondary to Medicare, which means that it typically pays after Medicare pays. In order to be fully covered, for Medicare-covered services you usually need both Part A and Part B.

If you only have retiree insurance and later decide to enroll in Medicare, you may have to pay a penalty for late enrollment in addition to the monthly premium. Part A is free for most people, but there is a monthly premium for Part B. Additionally, if you delay enrollment in Part B, you may also have gaps in your coverage, because you will have to wait until the General Enrollment Period to enroll in Part B. The General Enrollment Period is January 1 through March 31 each year, with coverage beginning July 1.

Note: Some federal retirees chose to decline Part B. Unlike most other retirees, federal retirees keep the same health insurance that they had when they were working. If a federal retiree declines Part B they will have to wait until the General Enrollment Period to enroll. They may also have to pay a penalty if they later choose to sign up for Part B.