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Do I need to enroll in Medicare if I have coverage from the ACA health insurance marketplace?

Yes. If you have health insurance from the Affordable Care Act (ACA) health insurance marketplace rather than from an employer, you’ll need to sign up for Medicare Part A and Part B when you’re eligible at age 65.

Sign up during your initial enrollment period, which begins three months before the month you turn 65 and ends three months after your birthday month. Otherwise, you’ll have to wait to enroll during the next general enrollment period, from Jan. 1 to March 31. You may also have to pay a lifetime late enrollment penalty.

While you don’t have to drop your ACA health insurance to enroll in Medicare, most people do. For people who qualify for premium-free Medicare Part A, marketplace insurance premium subsidies end after they’re eligible for Part A at age 65.

If you choose to keep the marketplace coverage, you’ll no longer be eligible for subsidies and will have to pay full price. And if the marketplace doesn’t adjust your premiums right away, you may have to pay back the extra subsidies when you file your federal income tax return.

Even though you can keep your marketplace coverage after you enroll in Medicare, you’re not able to get a new marketplace policy at that point. In fact, it’s against the law for someone who knows you have Medicare to sell you a marketplace health insurance plan, even if you have only Part A or Part B.

If you want extra coverage to help pay Medicare’s deductibles and copayments, you can buy a Medicare supplement policy, better known as Medigap, or you can choose to get your medical and drug coverage from a private Medicare Advantage plan, which must provide the same coverage as Medicare Part A and Part B but has different deductibles and copayments. But you must sign up for Medicare Part A and Part B before you can get a Medigap policy or a Medicare Advantage plan.

What happens if I have to pay a premium for Part A?

The rules are different for those who aren’t eligible for premium-free Medicare Part A. If you or your spouse worked for at least 40 calendar quarters, the equivalent of 10 years, and had Medicare taxes deducted from your pay, you won’t pay premiums for Part A.

If you or your spouse paid Medicare taxes for 30 to 39 quarters, you may have to pay Part A premiums of $274 a month in 2022, an amount often less than the least expensive marketplace premiums without a subsidy. 

That amount increases to $499 a month if you’ve worked fewer than 30 quarters.

People who don’t qualify for premium-free Medicare Part A can opt to keep their ACA marketplace health insurance rather than sign up for Medicare at 65. You’ll continue to receive subsidies to help pay the premiums, but they end if you enroll in Medicare.

Think carefully before making this decision: If you decide to sign up for Medicare later, you may need to wait until the general enrollment period and have to pay a late-enrollment penalty for Part A in addition to a Part B late penalty.

How do I switch from ACA coverage to Medicare?

You need to take a few steps when ending your health insurance from the ACA marketplace and enrolling in Medicare. An important part of the transition is ensuring that you have no gap between the end of your marketplace coverage and the beginning of Medicare.

The steps are different for those ending sole coverage vs. family coverage. Visit for step-by-step instructions on how to cancel a marketplace health insurance plan. If you live in one of the 17 states and the District of Columbia that runs its own ACA health insurance marketplace, visit your state’s site.

Ending coverage for you alone. Log in to your marketplace account at, click Start a new application or update an existing one. Then click your name at the top right of the screen and select My applications & coverage.

Select your application under Your existing applications, and on the left choose My Plans & Programs. At the bottom, click on the red End (terminate) all coverage button. Select the date you want to end your ACA plan, then click the Terminate Coverage button.

Ending your coverage but keeping it for others. When you turn 65 and enroll in Medicare, your younger spouse or other family members will need to remain on a marketplace plan. In this case, contact the marketplace call center to make sure you select your final date for coverage while their insurance continues.

You can also do this online by logging in to your marketplace account. Under Your existing applications, click Report a life change, once in the menu on the left and then again near the bottom of the resulting page. Then choose Report a change in my household’s income, size or other information, and follow the prompts.

For Who Needs Coverage? specify household members keeping the marketplace coverage and remove each person no longer using it. Update information for your household to determine if those continuing ACA coverage are eligible for subsidies.

Keep in mind

Medicare helps pay for many medical expenses after you turn 65. But it still has some costs, such as Part B premiums — $170.10 a month in 2022 or more for high earners — and deductibles and copayments or coinsurance for Medicare Part A and Part B.

If you have low income and assets, you may qualify for a Medicare Savings Program to help with the premiums and out-of-pocket costs.

Updated August 26, 2022



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