Yes. When you become eligible for Medicare, you'll generally need to enroll in both Medicare Parts A and B to get full benefits from your retiree plan. Retiree plans usually offer benefits that fill in the gaps in Medicare coverage and sometimes include extra benefits, like prescription drugs. Remember, retiree coverage is not a Medigap policy (www.medicare.gov).
Who pays first?
If you're retired and have Medicare and group health plan (retiree) coverage from a former employer, Medicare generally pays first for your health care bills and your group health plan coverage pays second.
What else you should consider
How your retiree group health plan coverage works depends on the terms of your specific plan. To be sure about your plan, check with your employer or union. Your employer or union, or your spouse's employer or union, might not offer any health coverage after you retire.
If you can get group health plan coverage after you retire, it might have different rules, and might not work the same way with Medicare as it did when you were actively working.
If you decide to drop your retiree coverage, you might not be able to get it back, so carefully consider your options first.