Even if you keep working after you turn 65, you should sign up for Medicare Part A. If you have health coverage through your employer or union, Part A may still help pay some of the costs not covered
by your group health plan.You may want to wait to sign up for Medicare Part B if you or your spouse are working and have group health coverage through you or your spouse’s employer or union. (See note below if you work for a small company.) You would have to pay the monthly Medicare Part B premium, and the Medicare Part B benefits may be of limited value to you as long as the group health plan is the primary payer of your medical bills. In addition, you would start your 6-month Medigap open enrollment period during a time when it will not be of most use to you.
Note: If you are age 65 or older and working for a small company (less than 20 employees), you should talk to your employee health benefits administrator before making any decision not to take Medicare Part B. If your employer has less than 20 employees, Medicare is the primary payer and your group health insurance would be the secondary payer. If you are disabled and working (or you have coverage from a working family member), the Special Enrollment Period rules also apply.