When you turn 65, you should sign up for Medicare and notify your Marketplace plan that you now qualify for Medicare coverage. Your Marketplace coverage will not be cancelled automatically by your plan when you turn 65 and sign up for Medicare, but if you receive premium tax credits to help you pay for your Marketplace plan premium, your eligibility for these tax credits will end when your Medicare Part A coverage starts (people with Medicare are not eligible for these tax credits, and the premium tax credit can only be used for the purchase of Marketplace coverage, not Medicare).
If you choose to enroll in Medicare Part A and keep your Marketplace coverage, you will have to pay the full price for your Marketplace plan, and Medicare will be the primary payer. If you were receiving financial assistance for your Marketplace coverage prior to signing up for Medicare, you will receive a letter in the mail from the Marketplace informing you that you are no longer eligible to receive this financial assistance since you are enrolled in Medicare Part A. You should contact your Marketplace plan to make sure that your financial assistance is stopped when your Medicare coverage begins. If you do not stop receiving the premium tax credit and other financial assistance for your Marketplace plan when your Medicare coverage begins, you may have to repay some or all of the amount of financial assistance you received for the months you had both types of coverage.
If you decide to drop your Marketplace coverage when you become eligible for Medicare, make sure your Medicare coverage has started before you cancel your Marketplace plan so that you avoid any gaps in coverage. You can start signing up for Medicare three months before your 65th birthday.