Medicaid does not stop at 18. Federal law requires every state to cover children through at least their 19th birthday, and a separate rule keeps most enrollees covered for a full 12 months at a time regardless of birthdays or mid-year changes.1Medicaid. Continuous Eligibility for Medicaid and CHIP Coverage What does change once you turn 18 is how your eligibility is measured the next time it comes up for renewal.
What Actually Happens on Your 18th Birthday
Nothing, in most cases. Since January 1, 2024, every state must give children under 19 twelve months of continuous eligibility in both Medicaid and CHIP. During that window your coverage cannot be terminated because your family’s income changed, because you got a job, or because you had a birthday.1Medicaid. Continuous Eligibility for Medicaid and CHIP Coverage
So a 17-year-old whose coverage was renewed in March keeps that coverage through at least the following February, even after turning 18 in the meantime. The turning point is the end of your current enrollment period, or your 19th birthday, whichever comes first.
How Adult Medicaid Rules Are Different
When your state agency next reviews your case, it applies adult eligibility rules instead of children’s rules. That matters because children’s Medicaid often reaches families well above 200% of the federal poverty level, while adult thresholds sit lower. Federal law sets the children’s floor at 133% of poverty, and most states go higher for kids.2USAGov. How to Apply for Medicaid and CHIP
For most non-elderly, non-disabled adults, states measure income using Modified Adjusted Gross Income, which follows federal tax rules for figuring household size and income.3Office of the Law Revision Counsel. 42 US Code 1396a – State Plans for Medical Assistance Whether you qualify as an adult depends heavily on which state you live in:
- In the 40 states plus D.C. that expanded Medicaid, coverage reaches nearly all adults with household income up to 138% of the federal poverty level. For a single person in 2026, that is roughly $22,025 in annual income.4HHS ASPE. 2026 Poverty Guidelines
- In non-expansion states, adults without dependent children face much tighter eligibility and may not qualify for Medicaid at any income level, which creates a gap between Medicaid and marketplace subsidies.
Your state agency will send notice when it’s time to redetermine your eligibility. Respond promptly. Ignoring mail from the Medicaid agency is the single most common way young adults lose coverage they still qualify for.
New Federal Rules Taking Effect in Late 2026
The One Big Beautiful Bill Act, signed into law on July 4, 2025, makes two changes that hit young adults transitioning out of children’s Medicaid.
The first is a community engagement requirement. Adults ages 19 to 64 will need to work, volunteer, or take part in qualifying activities for at least 80 hours a month to keep Medicaid, unless they meet an exemption based on a medical condition, caregiving responsibilities, or other specified reasons. This is new territory for the program and applies from the moment you enter adult eligibility.
The second is a shorter retroactive coverage window. Medicaid has long paid for care you received in the 90 days before you applied, as long as you were eligible during that time. Starting December 31, 2026, that window shrinks to 30 days for adults covered through Medicaid expansion and 60 days for people in traditional eligibility categories. If you’re approaching 19 and think you’ll qualify as an adult, apply before your children’s coverage ends rather than after a gap opens.
If You Get SSI or Have a Disability
Young people receiving Supplemental Security Income face an extra step at 18. During the year after your 18th birthday, the Social Security Administration performs a disability redetermination that re-evaluates your condition under the adult standard rather than the children’s standard.5Social Security Administration. Code of Federal Regulations 416.987 The adult test is harder: instead of showing “marked and severe functional limitations,” you have to show you cannot engage in substantial gainful activity. A meaningful share of young people lose SSI at this stage.
Losing SSI can also mean losing Medicaid, because many states automatically link the two.6Social Security Administration. Understanding Supplemental Security Income Redeterminations If you get an unfavorable decision, you can appeal and request that your benefits continue during the appeal. The written notice SSA sends before the redetermination spells out those rights.
Keeping Medicaid After You Start Working
If you have a disability and start earning too much for an SSI check, Section 1619(b) can keep your Medicaid going. You stay eligible as long as you still meet the disability requirement, need Medicaid to keep working, and earn under your state’s threshold. Those thresholds vary widely. In 2026 they run from about $40,000 in states like Alabama and Arkansas to more than $84,000 in Minnesota.7Social Security Administration. Continued Medicaid Eligibility (Section 1619(B)) If you earn above the standard threshold, SSA can calculate an individualized one that reflects impairment-related work expenses or higher-than-average medical costs.
If You Were in Foster Care
Aging out of foster care carries one of the strongest protections in the Medicaid system. If you were in foster care and enrolled in Medicaid when you aged out, you qualify for Medicaid until age 26 with no income test at all, and every state must offer this.8Centers for Medicare and Medicaid Services. Medicaid State Plan Eligibility – Former Foster Care Children
Timing is what matters. You must have been in foster care and enrolled in Medicaid at the point you aged out, whether that was 18 or a higher age up to 21 depending on the state.9Centers for Medicare and Medicaid Services. Medicaid and CHIP FAQs – Coverage of Former Foster Care Children Leaving foster care before that age closes this door. The SUPPORT Act also made the benefit portable across states for young people who turned 18 on or after January 1, 2023.10Administration for Children and Families. Information Memorandum ACYF-CB-IM-23-04
If You Do Lose Medicaid
Two backup options cover most young adults.
A parent’s health plan is usually the simplest. Federal law requires every group and individual health plan that offers dependent coverage to keep adult children on until age 26.11GovInfo. 42 US Code 300gg-14 – Extension of Dependent Coverage The plan cannot require you to be a student, live at home, be financially dependent, or be unmarried. Age and the plan offering dependent coverage are the only tests, and the plan must offer you the same benefits at the same cost as other dependents.12U.S. Department of Labor. Young Adults and the Affordable Care Act FAQs One boundary worth knowing: this provision covers you, not your own children.
The ACA marketplace is the other route. Losing Medicaid opens a special enrollment period, and you have up to 90 days after coverage ends to pick a marketplace plan.13Centers for Medicare and Medicaid Services. Understanding Special Enrollment Periods Premium tax credits can cut the monthly premium based on your income,14Internal Revenue Service. 15HealthCare.gov. Cost-Sharing Reductions For a young adult with little income, the combination can make a marketplace plan nearly free.
What to Do Before Your Coverage Renews
Medicaid asks for renewal at least once every 12 months. States first try to confirm your eligibility from data they already have, such as tax records and wage databases. If the data confirms you qualify, renewal happens automatically and you get a notice. If something is missing, the state sends a form asking only for what it still needs.16Centers for Medicare and Medicaid Services. Overview of Medicaid and CHIP Eligibility Renewals
Return that form on time. Make sure the state has your current address, phone, and email so notices reach you. If you have moved out on your own, update the agency directly rather than assuming a parent will forward the mail. An unanswered renewal form is the most common cause of a lost-coverage letter arriving a month later, and by then the clock on your marketplace special enrollment period has already started.