For most people with retiree health benefits, it makes sense to sign up for Medicare when you are first eligible to do so. Retiree health plans are typically designed to supplement Medicare, and might not pay your medical costs during any period that you were eligible for Medicare but not signed up for it. You should review any information provided by your employer to be sure you understand how your retiree health benefits coordinate with Medicare. For example, some employers offer a fixed payment that retirees can use to purchase supplemental insurance. Others offer retiree health benefits exclusively through Medicare Advantage plans. Be sure to find out if your retiree health plan provides prescription drug coverage that is as good as what Medicare Part D plans provide; if it does not, you will need to sign up for a Medicare prescription drug plan to avoid a late enrollment penalty.

If you are not receiving Social Security benefits at age 65 when you are first eligible for Medicare, you will need to sign up for Part A and Part B. You can sign up for Medicare online at https://www.ssa.gov/medicare/sign-up, by calling Social Security, or at your local Social Security office. If you are already receiving your Social Security benefits, you should be automatically enrolled in both Part A and Part B when you turn 65.