Title XIX is a section of the Social Security Act that created Medicaid, the public health insurance program for people with low incomes. Signed into law in 1965, it established a partnership between the federal government and state governments to pay for medical care for eligible individuals and families. Today, about 68 million people are enrolled in Medicaid across the United States, making it one of the largest health coverage programs in the country.
You’ll most often see the term “Title XIX” in legal documents, government paperwork, and policy discussions. In everyday life, the program it created is simply called Medicaid.
How Title XIX Works
Title XIX set up Medicaid as a joint venture. The federal government writes the broad rules, and each state designs and runs its own version of the program within those rules. This means Medicaid looks different depending on where you live. Each state decides its own eligibility standards, which services to offer beyond the federal minimum, how much to pay healthcare providers, and how to manage the program day to day.
To participate, every state files a document called a “state plan” with the Centers for Medicare & Medicaid Services (CMS), the federal agency that oversees the program. This plan is essentially an agreement: the state promises to follow federal requirements, and in return, it receives federal matching funds. When a state wants to change its program, whether that means covering a new group of people or adding a benefit, it submits a state plan amendment to CMS for approval.
Who Qualifies for Coverage
Medicaid doesn’t cover everyone below a certain income level. Eligibility has always been tied to specific categories of people, not just income alone. Federal law requires every state to cover certain groups, called mandatory eligibility groups. These include:
- Children in low-income families and pregnant women with household incomes at or below 133% of the federal poverty level
- People receiving Supplemental Security Income (SSI), which covers individuals who are aged, blind, or disabled with very low income
- Children in foster care
When the program first launched, states were required to cover people already receiving federal cash assistance, including older adults, people with disabilities, and families with dependent children. Over the decades, Congress expanded these mandatory groups significantly.
The Affordable Care Act in 2010 added another mandatory group: adults under 65 with incomes at or below 138% of the federal poverty level (roughly $20,800 for a single person in 2025) who aren’t pregnant and don’t have Medicare. However, a 2012 Supreme Court ruling made this expansion optional for states. As a result, some states have adopted Medicaid expansion and others have not, creating a patchwork of eligibility across the country. In states that haven’t expanded, many low-income adults without children or a disability still don’t qualify regardless of how little they earn.
What Medicaid Covers
Title XIX requires every state Medicaid program to cover a core set of medical services. These mandatory benefits include inpatient and outpatient hospital care, physician visits, lab work and X-rays, nursing facility care, home health services, family planning, and transportation to medical appointments. For children, there’s a particularly comprehensive benefit called Early and Periodic Screening, Diagnostic, and Treatment services, which requires states to provide whatever medically necessary care a child needs, even if it isn’t on the standard benefits list.
Beyond the mandatory list, states can choose to cover additional services. These optional benefits include prescription drugs, dental care, eyeglasses, physical and occupational therapy, personal care services, and mental health treatment in certain facilities. Most states do cover prescription drugs and many of the other optional benefits, but coverage varies. This is one reason two people in different states with identical incomes and health needs can have very different Medicaid experiences.
How the Federal Government Shares Costs
The federal government doesn’t just set rules. It picks up a significant share of the tab. Each state receives a Federal Medical Assistance Percentage, or FMAP, which determines how much of every Medicaid dollar comes from federal funds versus state funds. By law, the federal share can’t drop below 50% and can’t exceed 83%.
Wealthier states receive the minimum 50% match, meaning they split costs evenly with the federal government. Lower-income states receive a higher federal share. For fiscal year 2025, state FMAP rates range from 50% to about 77%. The formula is based on each state’s per capita income compared to the national average, so it adjusts over time as economic conditions change.
Title XIX vs. Title XVIII (Medicare)
Title XIX (Medicaid) and Title XVIII (Medicare) were both created in 1965 as part of the same legislation, but they serve different populations and work in fundamentally different ways.
Medicare is a federal program for people 65 and older, people with certain disabilities who have received benefits for at least 24 months, and people with end-stage kidney disease. It’s funded primarily through payroll taxes and premiums. The federal government runs it directly, and the rules are the same nationwide.
Medicaid, by contrast, is for people with low incomes who fall into eligible categories. It’s funded through a mix of federal and state money, and each state administers its own program. Eligibility rules, covered benefits, and provider payment rates all differ from state to state. Some people, particularly low-income seniors and individuals with disabilities, qualify for both programs simultaneously. These “dual-eligible” individuals typically have Medicare as their primary coverage, with Medicaid filling in gaps like long-term care and out-of-pocket costs.
Why the Term Comes Up
Most people interact with Medicaid without ever hearing “Title XIX.” The term tends to surface in specific contexts: government benefits letters, legal proceedings, nursing home billing, or policy debates. If you’ve seen it on paperwork, it’s simply the legal citation for the law that authorizes Medicaid. Any reference to Title XIX of the Social Security Act is a reference to Medicaid, its eligibility rules, its benefit requirements, or its funding structure. Nothing more, nothing less.