How to Transition from the Health Marketplace to Medicare

When you become eligible for Medicare, sign up during your 7-month Initial Enrollment Period and end your Health Insurance Marketplace plan the day your Medicare coverage begins. You can technically keep a Marketplace plan after Medicare starts, but you lose the premium tax credits that made it affordable, and a Marketplace plan does not let you delay Part B without a lifelong penalty. This guide walks through the timing so you switch without a coverage gap or an avoidable surcharge.

If you bought health insurance through the Marketplace (also called the Affordable Care Act exchange or Healthcare.gov), turning 65 changes your options. Medicare becomes your primary coverage, and the subsidies that lowered your Marketplace premium go away.

Marketplace coverage and Medicare are not meant to overlap

You can keep your Marketplace plan until your Medicare coverage starts, and technically you can keep it afterward. But once you are eligible for premium-free Part A, you are no longer eligible for the premium tax credits or cost-sharing reductions that made your Marketplace plan cheaper. Keeping both usually means paying full price for coverage you no longer need.

Two rules matter here. First, a Marketplace plan has no effect on how your Medicare works once both are active. Second, you cannot buy a new Marketplace plan after your Medicare coverage begins. It is against the law for someone to knowingly sell a Marketplace plan to a person enrolled in any part of Medicare.

Your Initial Enrollment Period sets the clock

Most people qualify for Medicare at 65. Your Initial Enrollment Period is a 7-month window: the 3 months before the month you turn 65, your birthday month, and the 3 months after. Enrolling in the first 3 months means your coverage can start the month you turn 65, which is the cleanest way to line up the end of your Marketplace plan with the start of Medicare.

If you are already receiving Social Security benefits, you are usually enrolled in Part A and Part B automatically. If you are not, you sign up yourself through the Social Security Administration. Either way, do not wait for your Marketplace plan to "run out," because it will not cancel itself when Medicare starts.

A Marketplace plan does not protect you from the Part B penalty

This is the mistake that costs people the most money. Active employer coverage can let you delay Part B without a penalty. A Marketplace plan cannot. It is not considered creditable coverage for the purpose of delaying Part B, and losing it does not trigger a Special Enrollment Period.

If you skip Part B during your Initial Enrollment Period while relying on a Marketplace plan, you may have to wait for the General Enrollment Period (January 1 to March 31) to sign up, and you will likely owe a Part B late-enrollment penalty. That penalty is 10% of the standard premium for each full 12-month period you could have had Part B but did not, and it is added to your premium for as long as you have Medicare.

What it costs once you move to Medicare

The standard Part B premium is $202.90/month with an annual deductible of $283/year (as of the CMS 2026 release, higher earners pay more through IRMAA). Most people pay no premium for Part A because they paid Medicare taxes while working.

Because Original Medicare does not cap your out-of-pocket costs on its own, most people add either a Medicare Advantage plan or a Medicare Supplement plus a Part D drug plan. A licensed advocate can compare what your total monthly cost looks like on Medicare versus what you were paying, subsidy included, on the Marketplace.

How to make the switch step by step

• Confirm your Medicare eligibility date, which is usually the first day of the month you turn 65.
• Enroll in Part A and Part B during the first 3 months of your Initial Enrollment Period so coverage starts on time.
• Choose your added coverage: a Medicare Advantage plan, or a Medicare Supplement plus a standalone Part D plan.
• Contact the Marketplace to end your plan, setting the termination date for the day before your Medicare coverage starts so there is no gap and no overlap.
• If your spouse or dependents were on your Marketplace plan, arrange their coverage separately before you cancel, since they may not be Medicare-eligible.

Frequently asked questions

Can I keep my Marketplace plan after Medicare starts?

You can, but it rarely makes sense. Once you are eligible for premium-free Part A, you lose the premium tax credits and cost-sharing reductions, so you would pay full price for a plan that now sits behind Medicare. Most people end the Marketplace plan when Medicare begins.

Does a Marketplace plan let me delay Part B without a penalty?

No. Only active employer group coverage lets you delay Part B penalty-free. A Marketplace plan is not creditable coverage for that purpose, and losing it does not open a Special Enrollment Period. Enroll during your Initial Enrollment Period to avoid the lifelong penalty.

When should I cancel my Marketplace plan?

Set the end date for the day before your Medicare coverage starts. That avoids both a gap in coverage and a period where you are paying for two plans at once.

What happens if I already missed my Initial Enrollment Period?

You can sign up during the General Enrollment Period, January 1 to March 31, with coverage starting the first of the following month. You may owe a Part B late-enrollment penalty, so talk to a licensed advocate about your specific timeline.

Talk to a licensed Medicare advocate

Moving from the Marketplace to Medicare is mostly about timing, and the timing is easy to get wrong when you are doing it once. A licensed Medicare advocate can confirm your enrollment dates, line up your new coverage, and help you end your Marketplace plan cleanly. There is never a cost to you for that help.