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When Can I Enroll in Medicare? Answers From Medicare Expert Charles MacKay

You might think that “When can I sign up for Medicare?” would be a simple question. Many people may think that you can sign up for Medicare as soon as you are age 65. Alas, that’s not always the case.

This is because Medicare has a few different rules for eligibility other than simply turning 65.

If you are interested in purchasing a private Medicare Advantage (Medicare Part C) plan or a Medicare Supplement Insurance (Medigap) plan, there are other eligibility requirements and enrollment periods that may affect when you can enroll in a plan.

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When can I sign Up For Original Medicare (Part A and Part B)?

Some people are automatically enrolled in Medicare Part A (hospital insurance) and Medicare Part B (medical insurance, which is optional) when they turn 65.

You should be automatically enrolled in both if you are already receiving Social Security or Railroad Retirement Board retirement benefits when you turn 65.

If you are not automatically enrolled, you may be able to sign up for Part A and/or Part B during certain Medicare enrollment periods.

  • For most people, their Medicare Initial Enrollment Period is the seven-month period centered on the month in which they turn 65.

    For example, if your 65th birthday is in May, your Initial Enrollment Period starts three months before your birth month (in this example, in February) and lasts until three months after your birth month (in this example, the end of August).

  • If you miss your Initial Enrollment Period (and if you are not eligible for a Medicare Special Enrollment Period), you may be able to enroll in Medicare Part A and/or Part B during the Medicare General Enrollment Period, which runs from January 1 to March 31 of each year.

  • You might have prior insurance that is roughly equivalent to Medicare, such as an employer health plan. This is called “creditable coverage.”

    If you have creditable coverage, you can sign up for Medicare Part A and/or Part B as soon as that creditable coverage ends. You will typically be given an eight-month Special Enrollment Period that starts the month your employment or medical coverage ends.

    If you do not take advantage of that Special Enrollment Period, you may have to wait for the next General Enrollment Period, which is January 1 through March 31 of each calendar year.

    Keep in mind, if you sign up during general enrollment, your coverage will not begin until July 1. If you wait too long to sign up (more than 12 months), you may have to pay a late enrollment penalty.

What happens if I don’t enroll in Medicare Part B when I’m first eligible?

Part B of Medicare is voluntary. Depending on the other health insurance coverage you have, you may want to consider enrolling in Part B.

If you do not enroll in Part B when you’re first eligible – and if you do not have creditable coverage – you will typically incur a 10 percent late enrollment penalty for each twelve months you were eligible for Part B but did not enroll.

The Part B late enrollment penalty is added to your Part B monthly premiums for the rest of the time that you remain enrolled in Part B.

When can I sign up for Medicare Supplement Insurance?

Medicare Supplement plans, also called Medigap plans, are sold by private insurance companies.

If you enroll in a Medigap plan during your Medigap Open Enrollment Period, Medicare Supplement Insurance companies cannot charge you higher premiums or deny you a policy based on your health.

Your Medigap Open Enrollment Period lasts for six months and starts as soon as you are at least 65 years old and enrolled in Medicare Part B.

If you do not enroll during the six months when you are first eligible, you may apply at any time of the year.

If it is outside of your six-month Medigap Open Enrollment Period, however, the insurer may ask you health questions and adjust your premiums to reflect any increased risk. They can also deny you a plan completely.

When can I enroll in a Medicare Advantage plan?

You can enroll in a Medicare Advantage plan during your Initial Enrollment Period. Once that passes, there is one period each year that allows you to review your coverage and make changes as needed.

The Medicare Annual Election Period (AEP) runs from October 15 to December 7 of each calendar year.

During this period, you can:

  • Change from Original Medicare to a Medicare Advantage plan

  • Change from a Medicare Advantage plan back to Original Medicare

  • Switch from one Medicare Advantage plan to another

  • Switch from a Medicare Advantage plan that doesn't offer prescription drug coverage to a Medicare Advantage Plan that offers prescription drug coverage

  • Switch from a Medicare Advantage plan that offers prescription drug coverage to a Medicare Advantage Plan that doesn't offer prescription drug coverage

  • Join a standalone Medicare Prescription Drug plan (Part D)

  • Switch from one Medicare Part D plan to another

  • Drop your Medicare prescription drug coverage completely

There may be other special circumstances that allow you to make changes to your Medicare Advantage plan outside of AEP.

When can I sign up for Medicare Part D?

If you do not enroll in a Part D plan during your seven-month Medicare Initial Enrollment Period and decide to enroll later on, you will likely have to wait until the next Annual Election Period, which runs from October 15 to December 7 of each calendar year.

If you didn’t sign up for Part D coverage when you first became eligible (and if you didn’t have other creditable drug coverage), then you will likely have to pay a Part D late enrollment penalty.

The penalty can vary based on how long you didn’t have Part D or creditable drug coverage, and your penalty amount could increase each year.


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Medicare expert Charles MacKay

Charles MacKay is the author of two health care books, including Medicare Made Easy. He has written over 300 academic papers, including many dealing with healthcare. He now lives in Pennsylvania.

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