The answer to that question is not as simple as it seems, as everyone’s situation is very different.
• If you are still actively employed and covered under your employer’s group plan, and your employer has 20 or more employees, and the drug coverage is considered creditable meaning at least as good as Medicare would provide (they are required to tell you that annually)
then you do not need to enroll in any part of Medicare. The answer is the same if you are covered under your spouse’s employer group plan.
• If you are retired and are covered under your former employer’s retiree group plan, in almost every case, your former employer will require you to take Medicare A & B when you are first eligible. Medicare will be your primary and your retiree plan will be secondary. The answer is the same if you are covered under your spouse’s employer’s retiree group plan. **One exception here would be if you are a retired Federal Government employee and are covered under Federal Employee Health Benefits (FEHB). They do not require you to take Medicare but highly encourage you to do so.
• If you are covered under COBRA, you must enroll in Medicare A & B when first eligible.
• If you are a retired service member and covered under Tricare, you are required to enroll in Medicare A & B in order to continue with Tricare For Life. If you are an active duty service member, however, you are not required to enroll in Medicare until just before you retire.
• If you have VA Benefits, it is recommended that you enroll in Medicare A & B when you are first eligible, although you are not required to do so.
• If you have CHAMPVA, you must enroll in Medicare A & B when first eligible in order to keep your CHAMPVA coverage.
• If you have a Marketplace plan or other individual insurance, you must enroll in Medicare A & B when first eligible. You cannot stay on your Marketplace plan once your Medicare begins. Most individual plans will not cover you if you are eligible for Medicare.
If you are covered under an employer group plan that is not considered credible, or you are a Federal Government retiree covered under FEHB, or you are covered under COBRA, or have VA coverage and do not elect Medicare A & B when first eligible and decide to do so later, your Part B premium will go up due to a 10% late enrollment penalty for each full 12-month period that you could have had Part B, but didn’t. In addition, if you decide not to take Medicare when you turn 65 but decide to do so later, at say age 67, you will have to wait until the General Enrollment Period (January 1 to March 31st) to apply and then your coverage will not start until July 1st of that
**Please note: if you were required to enroll in Medicare A & B to avoid the late enrollment penalty, you may also be subject to a Part D penalty if you did not have creditable prescription drug coverage from the date of first eligibility.