Can You Have Obamacare and Medicare at the Same Time?

You generally cannot have Obamacare and Medicare at the same time. Once your premium-free Medicare Part A begins, you lose eligibility for the premium tax credits and cost-sharing reductions that make marketplace plans affordable, and it’s against the law for anyone who knows you have Medicare to sell you a marketplace plan. A narrow exception exists for people who have to pay a monthly premium for Part A, but for almost everyone on Medicare, an ACA marketplace plan is off the table.¹

Why the Two Programs Don’t Overlap

The ACA marketplace was built for people who don’t have affordable coverage through an employer or a government program. Medicare is a government program, so the moment you’re eligible for premium-free Part A, the marketplace treats you as covered. Subsidy eligibility ends whether or not you’ve actually enrolled in Part A yet.

You can technically keep paying for a marketplace plan after Medicare starts, but you’ll owe the full unsubsidized premium, and your insurer can cancel the plan on its own. Anyone who knowingly sells you a marketplace plan while you have Medicare is breaking the law.¹

The rule doesn’t depend on age. People under 65 who qualify for Medicare through a disability, ALS, or end-stage renal disease face the same restriction. Once Medicare eligibility kicks in, marketplace subsidies stop.¹

The One Exception: When Part A Isn’t Free

Not everyone gets Part A at no cost. You need at least 40 quarters of Medicare-taxed work history (about 10 years) to qualify for premium-free Part A. If you’re short of that, you can buy into Part A, but the premiums are steep. In 2026, people with 30 to 39 quarters pay $311 per month, and those with fewer than 30 quarters pay $565 per month.²

If you’re in that group, you have a real choice. You can skip Part A, enroll in a marketplace plan instead, and receive premium tax credits and cost-sharing reductions the same as anyone else without Medicare. Compare the total costs carefully before deciding: a subsidized marketplace plan may beat paying for Part A, Part B, and supplemental coverage combined, but weigh that against the late enrollment penalties you could face if you eventually switch to Medicare.¹

This exception disappears the moment you become eligible for premium-free Part A. If your work record catches up, or a spouse’s record qualifies you, your marketplace subsidy eligibility ends four months later, whether you actually enroll in Part A or not.³

The Financial Risk of Staying on a Marketplace Plan After Medicare

This is where people get hurt. If you keep receiving advance premium tax credits on a marketplace plan after you become eligible for Medicare, you owe every dollar of those credits back at tax time. Starting with tax year 2026, there’s no cap on the repayment. Earlier years had income-based limits that softened the blow for lower-income households, and those limits have expired.⁴

A retiree who collects several months of marketplace subsidies after becoming Medicare-eligible can face a repayment of thousands of dollars. The IRS calculates it on Form 8962, and the full excess amount is added to your tax bill, cutting your refund or increasing what you owe.

How to Cancel Marketplace Coverage When Medicare Begins

Your marketplace coverage does not end automatically when Medicare starts. You have to cancel it yourself by updating your marketplace application. You can report a Medicare start date up to three months before your coverage actually begins, which lets you line the dates up cleanly.¹

Most people first qualify for Medicare at 65. Your Initial Enrollment Period covers seven months: the three months before the month you turn 65, your birthday month, and the three months after. Signing up for Part B in that window avoids late enrollment penalties.⁵

If your Medicare starts May 1, you can update your marketplace application as early as February 1, set the Medicare start date as May 1, and your marketplace plan ends April 30. That gives you continuous coverage with no gap and no overlap.

When Only One Spouse Is on Medicare

Couples with an age gap run into a common problem: one spouse qualifies for Medicare while the other still needs coverage. The younger spouse and any dependents can keep the marketplace plan with full subsidy eligibility, but only after you remove the Medicare-eligible spouse from the application.

To do that, update your marketplace application to end coverage for the person starting Medicare, then confirm the plan for everyone else. Subsidy eligibility for the remaining family members is based on household income, not on what the Medicare-enrolled spouse pays for Part B or supplemental coverage. Those Medicare premiums don’t reduce the younger spouse’s expected contribution toward marketplace premiums.¹

Forget to remove the Medicare-eligible spouse and the entire household’s premium tax credits are at risk. The marketplace calculates subsidies for the whole application, and keeping an ineligible person on it can trigger repayment for credits used on everyone’s coverage.

What If You’re Still Working at 65?

If you or your spouse are actively employed and have insurance through that current job, you can delay enrolling in Medicare Part B without a late penalty. The key word is “active.” The coverage must come from current employment, not a former employer.⁶

When you or your spouse stop working, or that employer coverage ends, whichever comes first, you get an eight-month Special Enrollment Period to sign up for Part B penalty-free. During your working years, employer coverage fills the gap, so a marketplace plan isn’t needed.⁶

COBRA and retiree plans feel like employer coverage, but Medicare treats them differently. Because you’re no longer actively working in the job that provided the coverage, neither qualifies you for a Special Enrollment Period or shields you from Part B late penalties. If you’re on COBRA when you turn 65, enroll in Medicare during your Initial Enrollment Period; COBRA becomes secondary once Medicare starts.⁷⁸

Medicare’s Part B and Part D late penalties are essentially permanent surcharges on your monthly premiums, which is a large part of why keeping a marketplace plan past your enrollment window is almost always a losing trade.⁹

Filling Gaps in Medicare Coverage

Since a marketplace plan can’t be used to supplement Medicare, three other options exist. Medicare Advantage (Part C) plans, sold by private insurers, replace Original Medicare and roll Part A, Part B, and usually Part D into one plan, often with an annual out-of-pocket cap ($9,250 for in-network services in 2026) that Original Medicare doesn’t have.¹⁰

Medigap policies sit alongside Original Medicare and pick up deductibles, copayments, and coinsurance that Medicare leaves you to pay. Your one-time, six-month Medigap open enrollment window starts the month you turn 65 and have Part B; during that window, insurers must sell you any policy they offer regardless of your health. After it closes, in most states insurers can deny you or charge more based on medical history. You cannot combine Medigap with Medicare Advantage.¹¹¹²

A standalone Part D plan adds prescription drug coverage if you stay with Original Medicare. If your income and resources are limited, the Extra Help program can significantly reduce Part D premiums, deductibles, and copayments; you apply through Social Security, and it’s available only to people on Medicare.¹³¹⁴

1
HealthCare.gov. Changing from Marketplace to Medicare
2
Centers for Medicare & Medicaid Services. 2026 Medicare Parts A and B Premiums and Deductibles
3
Medicare.gov. Medicare and the Health Insurance Marketplace
4
IRS. IRS Updates Frequently Asked Questions on the Premium Tax Credit
5
Medicare.gov. When Can I Sign Up for Medicare
6
Medicare.gov. Working Past 65
7
Social Security Administration. Special Enrollment Period (SEP)
8
Social Security Administration. Medicare Information
9
Medicare.gov. Avoid Late Enrollment Penalties
10
U.S. Department of Health and Human Services. What Is Medicare Part C
11
Medicare.gov. What’s Medicare Supplement Insurance (Medigap)?
12
Medicare.gov. Get Ready to Buy
13
Medicare.gov. What’s Medicare Drug Coverage (Part D)?
14
Medicare.gov. Help With Drug Costs