When a child on Medicaid turns 18, their coverage doesn’t automatically end, but it does get re-evaluated. The state will redetermine whether they still qualify, this time using adult eligibility rules instead of children’s rules. Depending on the state, the child’s income, and whether they have a disability or were in foster care, they may keep coverage, shift to a different Medicaid category, or lose it entirely.
Why Turning 18 Triggers a Review
Children qualify for Medicaid under rules that are generally more generous than those for adults. Income limits are higher, the benefits package is broader, and the process is simpler. At 18 (or in some cases 19, since CHIP covers children up to age 19), the state reassesses eligibility using adult criteria. This isn’t optional. Every young person aging out of children’s Medicaid goes through this redetermination.
You’ll typically receive a renewal notice in the mail before the redetermination happens. The notice will ask for updated information, particularly about income. Responding quickly matters. If you don’t return the paperwork, coverage can lapse even if your child would still qualify.
How Income Rules Change
Whether your child keeps Medicaid as an adult depends heavily on where you live. In the 40 states (plus Washington, D.C.) that have expanded Medicaid under the Affordable Care Act, any adult earning up to 138% of the federal poverty level qualifies. For a single person in 2024, that’s roughly $20,800 a year. Most 18-year-olds who are students, working part-time, or not working at all will fall under that threshold and stay covered.
In states that have not expanded Medicaid, the picture is much harder. These states often have no Medicaid category for healthy, childless adults regardless of how little they earn. An 18-year-old who earned nothing could still be ineligible simply because the state doesn’t cover non-disabled adults without children. These young people also fall into what’s known as a coverage gap: their income is too low to qualify for subsidized insurance through the Health Insurance Marketplace, and they don’t fit any remaining Medicaid category. If your child lives in a non-expansion state, losing coverage at 18 is a real possibility.
What Benefits Change at 18
Even if your child stays on Medicaid, the benefits they receive will likely shrink. Children on Medicaid are covered under a federal benefit called EPSDT (Early and Periodic Screening, Diagnostic, and Treatment), which is specifically designed to catch health problems early and treat them aggressively. It’s the most comprehensive benefit package Medicaid offers. Under EPSDT, states are required to provide any medically necessary service that falls within Medicaid’s broad service categories, even if the state doesn’t normally cover that service for adults.
EPSDT covers children and adolescents under 21, so depending on the state, your child may retain these enhanced benefits for a few more years. But once they age out of EPSDT, the adult Medicaid benefit kicks in. Adult coverage varies by state, but it’s generally narrower. Services like dental care, vision, physical therapy, and certain mental health treatments may be limited or unavailable. If your child has been receiving specialized treatments, check with your state’s Medicaid office about what will and won’t carry over.
The SSI Disability Redetermination
If your child receives Supplemental Security Income (SSI) due to a disability, turning 18 triggers a separate and significant review. The Social Security Administration re-evaluates their disability using adult criteria instead of the childhood standard. This is called an age-18 redetermination, and the outcomes are sobering: roughly 33 to 40 percent of young people lose their SSI eligibility through this process.
The childhood disability standard asks whether the child has a condition that causes “marked and severe functional limitations.” The adult standard is different. It focuses on whether the person can perform “substantial gainful activity,” essentially whether they can hold a job. A child who qualified under the broader childhood criteria may not meet the narrower adult test. Losing SSI typically means losing the automatic Medicaid eligibility that comes with it.
There is one important protection. If your child is participating in vocational training, an individualized education program (IEP), or a similar approved program when their disability determination changes, benefits can continue under a provision called Section 301. This applies to individuals ages 18 through 21 who stay enrolled in their program after the redetermination. If your child is in any kind of educational or vocational program, make sure the Social Security Administration knows before the review.
Former Foster Youth Get Extended Coverage
If your child was in foster care and enrolled in Medicaid when they turned 18 (or when they aged out of foster care at a higher age set by the state), federal law requires Medicaid coverage until age 26. This is one of the strongest protections in the system. There is no income test and no asset test. It doesn’t matter how much the young person earns or saves.
The key requirement is specific: the young person must have been both in foster care and enrolled in Medicaid at the time they aged out. Someone who left foster care before 18, or who wasn’t enrolled in Medicaid at the time, doesn’t qualify for this category. Youth who were in guardianship arrangements rather than formal foster care placements may also fall outside this protection, since federal guardianship assistance is treated differently from foster care under the law.
Switching From a Pediatrician to an Adult Provider
Beyond the paperwork, there’s a practical shift that catches many families off guard. Pediatricians generally stop seeing patients between ages 18 and 21, and most Medicaid managed care plans will eventually require your child to transition to an adult primary care provider. If your child has complex medical needs, this transition can be disruptive. Specialists they’ve seen for years may not accept adult Medicaid, or the referral process may work differently under their new coverage category.
Start this transition early if you can. Ask your child’s current doctors whether they’ll continue seeing them after 18, and whether their Medicaid plan’s provider network changes when they move to adult coverage. For young people with chronic conditions or disabilities, having medical records organized and a new provider identified before the birthday makes a real difference.
How to Prepare Before the Birthday
The single most important thing you can do is respond to any renewal paperwork promptly. States send redetermination notices by mail, and missed deadlines are the most common reason young people lose coverage they would otherwise keep.
- Check your state’s expansion status. If you’re in an expansion state and your child’s income is low, they’ll very likely stay covered. If you’re in a non-expansion state, start exploring Marketplace options early.
- Gather income documentation. The redetermination will be based on your child’s own income, not the household’s. If they’re a dependent student with little or no income, that works in their favor.
- Flag any disability benefits. If your child receives SSI, prepare for the age-18 redetermination separately. Document their participation in any educational or vocational programs.
- Check foster care records. If your child aged out of foster care while enrolled in Medicaid, make sure the state has documentation. This coverage is guaranteed through 26 with no income test.
- Update your mailing address. Renewal notices go to the address on file. If your child has moved or is heading to college, update the address with your state Medicaid office so nothing gets lost.
Coverage gaps are common during this transition, but most of them happen because of missed paperwork rather than actual ineligibility. Staying on top of the administrative process is the best way to keep your child covered.