Turning 18 does not end your Medicaid coverage. Federal law defines children’s Medicaid and CHIP as covering individuals under age 19, so what happens to Medicaid when you turn 18 is, in most cases, nothing at all.1Medicaid.gov. CHIP Eligibility and Enrollment The real transition comes on your 19th birthday, when your state re-evaluates your eligibility using adult rules and your own income rather than your parents’.
Why Your 18th Birthday Is Not the Cutoff
As long as you are 18, you remain in the children’s eligibility category. Your state continues to use your family’s household income and size to decide whether you qualify. Every state covers children in families earning at least 133% of the federal poverty level, and many set the cutoff at 200% or higher.2Medicaid.gov. Eligibility Policy Children whose family income is too high for Medicaid may still qualify for CHIP, which reaches further up the income scale.3Medicaid.gov. Medicaid, Children’s Health Insurance Program, and Basic Health Program Eligibility Levels
A federal continuous eligibility rule that took effect in January 2024 adds another layer of protection. Children under 19 enrolled in Medicaid or CHIP must receive 12 months of uninterrupted coverage, regardless of changes in family income during that period. Turning 18 is not an exception. Only turning 19, moving out of state, or death ends the 12-month window early.4Medicaid.gov. Continuous Eligibility If you were enrolled at 17 and your window has not closed, your state cannot terminate your coverage just because you had a birthday.
What Happens at 19
The shift to adult rules happens at 19. Your state Medicaid agency conducts a redetermination and re-evaluates whether you qualify as an adult. The biggest change is whose income counts. As a child, your parents’ income and household size drove the calculation. As an adult, your own income takes over under the Modified Adjusted Gross Income (MAGI) rules established by the Affordable Care Act.2Medicaid.gov. Eligibility Policy
Your state will send a notice by mail or electronically asking you to verify your current income, household size, and other eligibility factors. Respond quickly. If the agency can verify your information through existing data sources like tax records, you may not have to submit anything. But if it asks for documentation and you ignore the request, your coverage can be terminated even if you still qualify.5Medicaid.gov. Medicaid and CHIP Renewals and Redeterminations
Will You Still Qualify as an Adult
Whether you keep Medicaid at 19 depends heavily on where you live and how much you earn.
Expansion States
Forty-one states (including the District of Columbia) have expanded Medicaid under the ACA. In those states, adults under 65 with incomes up to 138% of the federal poverty level qualify. For a single person in 2026, that works out to about $22,025 per year, or roughly $1,835 per month.6U.S. Department of Health and Human Services. 2026 Poverty Guidelines If you are 19, working part-time or not at all, and living on your own, you will almost certainly fall under this limit in an expansion state. You don’t need to calculate the 138% figure yourself; your state handles the math during the application.2Medicaid.gov. Eligibility Policy
Non-Expansion States
In the 10 states that have not expanded Medicaid, the picture is far less favorable. Adult eligibility is often restricted to specific groups like pregnant individuals, parents of dependent children, or people with disabilities, and income limits can be dramatically lower. A young, non-disabled adult without children may not qualify at all, regardless of income.7HealthCare.gov. Medicaid Expansion and What It Means for You This creates the so-called coverage gap: adults who earn too little for Marketplace subsidies but too much for their state’s narrow Medicaid program. Applying anyway is still worthwhile, because your state may have coverage tied to pregnancy, disability, or other circumstances that are not obvious from the outside.
If Your Parents Still Claim You on Their Taxes
Many 18- and 19-year-olds are still claimed as tax dependents. MAGI rules generally tie your Medicaid household to your tax household, so if your parents claim you, you are typically counted with them and both incomes are evaluated together.8Centers for Medicare and Medicaid Services. Job Aid – Income Eligibility Using MAGI Rules
One nuance: a tax dependent’s own income only counts toward the household total if it is high enough to trigger a federal tax filing requirement. Summer job earnings below the filing threshold won’t be counted. If nobody claims you and you file your own return, your household is just you, and only your income matters. Different household rules apply if you are claimed by someone who is not your parent, or by a non-custodial parent.8Centers for Medicare and Medicaid Services. Job Aid – Income Eligibility Using MAGI Rules
Two Situations Where 18 Actually Does Matter
SSI Disability Redetermination
If you receive Supplemental Security Income based on a childhood disability, the Social Security Administration is required to reassess your disability using adult criteria within one year of your 18th birthday.9Social Security Administration. Redeterminations The adult and childhood disability standards are different, and a condition that qualified you as a child may not meet the adult threshold.
If SSA finds you are no longer disabled under adult rules, your SSI payments stop. In roughly 35 states plus the District of Columbia, Medicaid is automatically linked to SSI, so losing SSI triggers a Medicaid review as well.10Social Security Administration. Medicaid Information Losing SSI-based Medicaid does not necessarily mean losing all coverage. You may still qualify under the adult MAGI income rules, and some states run Medicaid waiver programs for people with disabilities that use different income and asset limits. If you are facing an SSI redetermination, contact your state Medicaid agency before the process begins to understand your options.
Former Foster Youth
If you were in foster care and enrolled in Medicaid when you turned 18 (or aged out at a higher age your state sets), you qualify for Medicaid until age 26 with no income test and no asset test.11Medicaid.gov. Medicaid and CHIP FAQs – Coverage of Former Foster Care Children This is one of the most generous Medicaid categories and one of the least well-known.
A significant change took effect in January 2023 under the SUPPORT Act. Previously, states only had to cover former foster youth who aged out in that same state. That requirement is gone for anyone who turned 18 on or after January 1, 2023. States must now cover qualifying former foster youth regardless of which state’s foster care system they came from.12Centers for Medicare and Medicaid Services. Former Foster Care Children Medicaid Policy Update If you aged out in one state and now live in another, you should be able to enroll in your current state under this category.
If You Lose Coverage
Fair Hearing Rights
If your Medicaid is denied or terminated, you have a federal right to appeal through a fair hearing before your state agency.13Office of the Law Revision Counsel. 42 USC 1396a – State Plans for Medical Assistance Your denial notice must explain how to request the hearing, and you generally have up to 90 days from the date the notice was mailed to file.14eCFR. Subpart E – Fair Hearings for Applicants and Beneficiaries
Timing matters. If you request the hearing before your coverage actually ends (typically within 10 days of receiving the termination notice), your state may be required to continue benefits while the appeal is pending. This is sometimes called aid paid pending. File later and your coverage stops during the appeal, which can leave you uninsured for months. Read the dates on your notice carefully.
Marketplace Coverage as a Backup
Losing Medicaid qualifies you for a Special Enrollment Period on the ACA Marketplace. You generally have 60 days from the date you lose coverage to enroll, though some exchanges extend this to 90 days for people losing Medicaid or CHIP.15Centers for Medicare and Medicaid Services. Special Enrollment Periods Job Aid
For the 2026 plan year, premium tax credits are available to individuals with household income between 100% and 400% of the federal poverty level. Enhanced subsidies that had temporarily removed the 400% cap expired at the start of 2026, so premium contributions are higher than they were in 2024 and 2025.16Congress.gov. Enhanced Premium Tax Credit and 2026 Exchange Premiums For most young adults aging out of children’s Medicaid, income is low enough that significant subsidies still apply. Your household income has to be at least 100% of the federal poverty level ($15,960 for a single person in 2026) to qualify for any premium tax credit.17Internal Revenue Service. Eligibility for the Premium Tax Credit
Retroactive Coverage
If you didn’t realize you needed to reapply and went a few months without coverage, federal Medicaid rules allow up to three months of retroactive coverage before the month you submit your application. You have to have been eligible during those earlier months and to have incurred medical expenses or been at risk of doing so. Not all states offer the full three months; some have federal waivers that shorten or eliminate the retroactive period. In most states, applying promptly after a lapse can get you backdated protection for bills you already owe.
How to Protect Your Coverage Through the Transition
The most common reason young adults lose Medicaid at 18 or 19 isn’t ineligibility. It’s a missed piece of mail. Keep your contact information current with your state Medicaid agency. If you’ve moved out of your parents’ home, started college in another town, or changed your phone number, update your information before the renewal notice arrives.
When the redetermination notice does come, respond promptly. You may need to provide proof of income (pay stubs or a tax return), your current address, and your household size. If you’re not working, say so. Zero income is a valid answer that will likely keep you eligible in an expansion state.5Medicaid.gov. Medicaid and CHIP Renewals and Redeterminations
If your coverage does lapse and you need to reapply, you can do so through your state’s Medicaid website, by mail, by phone, or in person at a local office. You can also start at HealthCare.gov, which routes your application to your state’s Medicaid agency if you appear to qualify. Navigators and community organizations in most areas offer free application help, which can be especially useful the first time you apply on your own.