The Affordable Care Act (ACA) and Medicaid are not the same thing, but they are closely connected. Medicaid is a government health insurance program that has existed since 1965, covering low-income Americans through a partnership between federal and state governments. The ACA, signed into law in 2010, is a broader health care law that made significant changes to Medicaid, most notably by giving states the option to expand who qualifies for it. The ACA also created the Health Insurance Marketplace, where people can buy private plans with subsidies, and made reforms like eliminating preexisting condition exclusions.
How the ACA Changed Medicaid
Before the ACA, Medicaid was mostly limited to specific groups: children, pregnant women, people with disabilities, and very low-income parents. In many states, a single adult without children couldn’t qualify no matter how little they earned. The ACA opened the door for states to extend Medicaid to nearly all adults under 65 with household income at or below 133% of the federal poverty level (effectively 138% after a built-in income deduction). For a single person in 2024, that translates to roughly $20,780 per year.
Beyond expanding eligibility, the ACA streamlined how people apply. A single application now works for Medicaid, the Children’s Health Insurance Program (CHIP), and subsidized Marketplace coverage. If you apply through Healthcare.gov and your income suggests you qualify for Medicaid, your information is automatically forwarded to your state’s Medicaid agency, which contacts you about enrollment. If you’re denied Medicaid, your information goes back to the Marketplace so you can explore private plan options instead.
Which States Have Expanded Medicaid
As of late 2025, 41 states (including Washington, D.C.) have adopted Medicaid expansion, while 10 states have not. The Supreme Court ruled in 2012 that the federal government couldn’t force states to expand, making it optional. States that chose to expand receive a higher federal matching rate for their newly eligible population compared to what they receive for their traditional Medicaid enrollees.
In the 10 states that haven’t expanded, eligibility rules remain far more restrictive. The median income limit for parents in non-expansion states is just 44% of the federal poverty level, roughly $8,985 a year for a family of three. Adults without dependent children are ineligible in most of these states regardless of income.
The Coverage Gap in Non-Expansion States
One of the most consequential effects of some states declining expansion is the “coverage gap.” This affects people who earn too much to qualify for their state’s traditional Medicaid but too little to qualify for subsidized Marketplace plans, which start at 100% of the federal poverty level. Nearly 2.5 million uninsured adults fall into this gap nationally. Adults without dependent children make up 77% of those affected, since most non-expansion states don’t cover childless adults through Medicaid at any income level.
Medicaid vs. Marketplace Plans
If you qualify for Medicaid, your coverage looks quite different from a private Marketplace plan. Medicaid charges zero or near-zero premiums and uses very little cost sharing, meaning you rarely face copays, deductibles, or surprise bills. Marketplace plans, even with subsidies, involve deductibles and other out-of-pocket costs. For low-income adults, Medicaid is significantly more effective at reducing out-of-pocket spending.
The trade-off is provider access. Because Medicaid pays doctors less than private insurance does, many physicians don’t accept Medicaid patients. People with private Marketplace plans generally have an easier time finding and seeing doctors. So Medicaid offers stronger financial protection, while Marketplace coverage often provides a wider choice of providers.
What Medicaid Expansion Covers
States that expand Medicaid must cover newly eligible adults through plans that include the ACA’s 10 Essential Health Benefits. These include prescription drugs, behavioral health services (mental health and substance use treatment), preventive care, dental care, and more. For children, Medicaid also includes comprehensive screenings, diagnostic services, and treatment through a program known as Early and Periodic Screening, Diagnosis, and Treatment. Coverage details vary somewhat by state, but the federal floor ensures a broad set of benefits.
Recent Enrollment Changes
Medicaid enrollment surged during the COVID-19 pandemic because a federal rule temporarily prevented states from removing anyone from the program. When that rule ended in April 2023, states began reviewing everyone’s eligibility in a process often called “unwinding.” The results were dramatic: overall enrollment dropped by about 14.9 million people. Of the 94.3 million individuals due for renewal through June 2024, about 55.1 million (58.4%) had their coverage renewed, while 20.7 million (22%) were terminated.
A striking detail in that data: only about 6.5 million of those terminations were because someone was actually found ineligible. The remaining 14.3 million were “procedural” terminations, meaning people lost coverage because they didn’t complete the renewal paperwork, not because they no longer qualified. Many of those individuals may still be eligible and could re-enroll by contacting their state Medicaid office.
How to Know Which Program You Qualify For
Your income and your state of residence determine whether you fall into Medicaid, a subsidized Marketplace plan, or potentially the coverage gap. If you live in an expansion state and your income is at or below 138% of the federal poverty level, you likely qualify for Medicaid. If your income is higher, you may qualify for premium tax credits on a Marketplace plan that cap what you pay based on your income. In non-expansion states, you’ll need to check your state’s specific Medicaid rules, which vary widely.
The simplest starting point is to fill out an application at Healthcare.gov (or your state’s marketplace if it runs its own). The system automatically determines whether you’re eligible for Medicaid, CHIP, or subsidized private coverage and routes you accordingly.