When you stop working and/or your group health insurance coverage ends, you should enroll in Medicare Part A and Part B. If you’re eligible for premium-free Part A, you can sign up any time after you’re first eligible for Medicare. Your Part A coverage will go back retroactively 6 months from when you sign up (but no earlier than the first month you were eligible). You have an 8-month Special Enrollment Period (SEP) to enroll in Part B after your employment (and/or group coverage) ends to avoid facing a penalty for late enrollment. You may want to sign up for Part B in the few months before your group coverage ends to avoid a gap in coverage.
If your employer does not offer retiree health benefits for former employees on Medicare, you will also want to sign up for a Medicare Part D plan. If you opt for traditional Medicare, you can purchase a Medicare supplemental policy, also known as Medigap, which helps pay your Medicare cost-sharing requirements. You can also choose to get your Medicare-covered Part A, Part B and, typically, Part D benefits through a private Medicare Advantage plan. In that case, you won’t need to enroll in a Medigap policy or a separate stand-alone Part D plan.