Obamacare and Medicaid are not the same thing, but they’re closely connected. Obamacare is the common name for the Affordable Care Act (ACA), a broad health care law passed in 2010. Medicaid is a specific government insurance program for low-income Americans that has existed since 1965. One of the biggest things Obamacare did was expand Medicaid to cover millions more people, which is why the two terms get tangled together.
How Obamacare Changed Medicaid
Before the ACA, Medicaid eligibility varied wildly by state and was limited mostly to specific groups: children, pregnant women, people with disabilities, and very low-income parents. In many states, a childless adult couldn’t qualify for Medicaid no matter how little they earned.
The ACA changed that by expanding Medicaid eligibility to nearly all adults aged 18 to 65 with household incomes up to 138% of the federal poverty level, which works out to about $21,597 a year for an individual in 2025. This was a massive shift. For the first time, low-income adults without children or disabilities had a path to Medicaid coverage in states that adopted the expansion.
The law also simplified how states determine eligibility. Previously, each state used its own patchwork of income calculations with different deductions. The ACA introduced a single, standardized income formula called modified adjusted gross income (MAGI), used across both Medicaid and the marketplace. It also created a single application for Medicaid, the Children’s Health Insurance Program (CHIP), and subsidized marketplace coverage, so applicants don’t need to figure out which program to apply to on their own.
Why Not Every State Expanded
The ACA originally required all states to expand Medicaid or risk losing their existing federal Medicaid funding. In 2012, the Supreme Court struck down that requirement in National Federation of Independent Business v. Sebelius. Seven justices ruled the mandatory expansion was unconstitutional, but five justices, led by Chief Justice John Roberts, crafted a compromise: states could choose not to expand without losing the federal funding they already received. Expansion became optional.
Over three-quarters of states have now opted to expand. But in the states that haven’t, many low-income adults fall into what’s known as a “coverage gap.” They earn too much to qualify for their state’s traditional Medicaid (the median income limit for parents in non-expansion states is just 44% of poverty) but too little to qualify for subsidized marketplace coverage, which starts at 100% of the federal poverty level. In nearly all non-expansion states, childless adults remain completely ineligible for Medicaid regardless of income.
Medicaid vs. Marketplace Plans
Obamacare created two main pathways to coverage. If your income falls below 138% of the federal poverty level in an expansion state, you’re directed to Medicaid. If your income is higher, you can buy a private plan through the Health Insurance Marketplace (HealthCare.gov or your state’s exchange) and potentially receive tax credits to lower your premium.
The financial difference between the two is significant. Medicaid enrollees pay an average of about $45 per year in out-of-pocket costs. Marketplace enrollees, even with federal subsidies, pay around $569 per year out of pocket. The per-visit gap is even more striking: an office visit costs Medicaid enrollees about $2.80 on average, compared to about $20 for marketplace enrollees. An emergency room visit averages $7.27 out of pocket with Medicaid versus $106 with a marketplace plan. Prescriptions cost about $2.40 per fill under Medicaid compared to nearly $7 under marketplace coverage.
Marketplace plans do require monthly premiums (though subsidies can reduce them to zero for some people). Medicaid generally has no premiums or very minimal ones. Both types of coverage include the ACA’s core protections: no denial for preexisting conditions, no annual or lifetime caps on benefits, and coverage of essential health benefits like hospital stays, prescriptions, maternity care, and mental health services.
How the Application Process Works
When you apply through HealthCare.gov or your state’s marketplace, the system automatically checks whether you qualify for Medicaid or CHIP based on your income and household size. If you do, your application is routed to your state’s Medicaid agency. If you don’t, you’ll see results for marketplace plans and any premium tax credits you’re eligible for. You get your eligibility results right away after submitting.
If you’re denied Medicaid or lose coverage, you can return to the marketplace to update or create an application and check your eligibility for a private plan. The system is designed so you don’t have to navigate between programs yourself.
What Obamacare Did Beyond Medicaid
The Medicaid expansion gets the most attention, but the ACA reshaped health insurance more broadly. It banned insurers from denying coverage or charging more based on preexisting conditions. It required plans to cap out-of-pocket costs annually. It allowed young adults to stay on a parent’s insurance until age 26. And it created the marketplace where individuals and families can comparison-shop for plans with standardized benefit levels.
Enrollment and spending in Medicaid increased in every state after the ACA passed, including states that didn’t expand. That’s partly because the law’s streamlined enrollment process and outreach efforts helped people who were already eligible for traditional Medicaid but hadn’t signed up. The ACA also set a uniform minimum eligibility threshold for children at 133% of the federal poverty level across all states, requiring some states to shift older children from separate CHIP programs into Medicaid.
So while Obamacare and Medicaid overlap in important ways, thinking of them as the same thing misses the picture. Medicaid is one program. Obamacare is the law that expanded it, created the marketplace, and overhauled insurance rules across the board.