When your child turns 18, the law treats them as an adult overnight. You lose automatic authority over their medical care, their school records, and their money, and your child picks up new obligations with hard deadlines attached. Knowing what to do when your child turns 18 comes down to a handful of documents signed before the birthday, a few registrations completed shortly after, and a clear-eyed look at what changes in your financial and legal relationship.
Sign Three Documents Before the Birthday
The most urgent task is also the one most families miss. If your 18-year-old is in a car accident or hospitalized and cannot speak for themselves, the hospital has no obligation to tell you what happened, let you into the room, or take direction from you. Three documents prevent that outcome, and all three should be signed while things are calm.
Healthcare Power of Attorney
A healthcare power of attorney lets your child name someone, typically a parent, to make medical decisions if they become unable to speak for themselves. The document identifies the principal (your child) and the agent (you or another trusted person), and it takes effect only when the principal is incapacitated. Execution rules vary by state, but nearly all require the principal’s signature plus either two witnesses or notarization.
Living Will
A living will spells out which medical treatments your child does or does not want at the end of life, such as CPR, mechanical ventilation, or tube feeding. The healthcare power of attorney gives an agent flexibility to respond to situations nobody anticipated; the living will locks in specific preferences for life-sustaining treatment. The two documents work together, and having only one leaves gaps.
Durable Financial Power of Attorney
A durable financial power of attorney authorizes an agent to handle money matters if your child becomes incapacitated: paying bills, managing bank accounts, signing contracts, filing tax returns. “Durable” means the authority continues even after the principal loses mental capacity, which is precisely when it matters. Your child should spell out which powers the agent holds, because an overly broad grant can be risky and a narrow one can leave important matters uncovered.
Having an attorney draft all three documents typically costs between $400 and $900, and many state bar associations offer free or low-cost templates. Notary fees usually run $5 to $10 per notarial act, though a handful of states let notaries set their own rates. Once the documents are signed, give copies to the family doctor, the hospital your child is most likely to use, and any financial institution where your child has accounts. Without them, you would need to petition a court for guardianship or conservatorship to make decisions, a process that takes weeks and costs thousands.
HIPAA and FERPA Releases
HIPAA closes off medical information at 18. Providers cannot share treatment details, diagnoses, or test results with parents unless the patient has signed an authorization.1U.S. Department of Health & Human Services. Personal Representatives and Minors A HIPAA release signed before your child leaves home is one of the single most important items on this list. It operates alongside the healthcare power of attorney but covers a different situation: the authorization lets you receive information even when your child is conscious and competent, while the power of attorney lets you make decisions when they are not.
FERPA does the same thing for school records. All rights over a student’s educational records transfer to the student once they turn 18 or enroll in a postsecondary institution at any age. The student becomes an “eligible student,” and schools generally cannot release grades, financial account information, or disciplinary records to parents without written consent.2U.S. Department of Education. An Eligible Student Guide to the Family Educational Rights and Privacy Act (FERPA) Have your child sign a FERPA release through the college’s registrar office early in enrollment so you can see grades and billing statements.
Health Insurance Through Age 26
Federal law requires any health plan that offers dependent coverage to keep adult children on a parent’s policy until they turn 26.3Office of the Law Revision Counsel. 42 U.S. Code 300gg-14 – Extension of Dependent Coverage This covers employer-sponsored group plans and individual market policies. The plan cannot deny or restrict coverage based on whether your child is married, employed, living at home, enrolled in school, or eligible for insurance through their own employer.4eCFR. 45 CFR 147.120 – Eligibility of Children Until at Least Age 26
Plans also cannot charge a higher premium for older dependents than for younger ones.4eCFR. 45 CFR 147.120 – Eligibility of Children Until at Least Age 26 Keeping your child on your plan is usually the cheapest option until they have coverage through their own job. When they turn 26 or lose dependent eligibility, they qualify for a Special Enrollment Period to buy their own plan through the marketplace.5HealthCare.gov. Get or Change Coverage Outside of Open Enrollment Special Enrollment Periods
Money and Credit
Custodial Accounts
If you set up a custodial account under the Uniform Transfers to Minors Act or Uniform Gifts to Minors Act, the assets legally belong to your child once they reach the age of majority defined by your state. That age is not always 18. Depending on the state and the type of transfer, it can be 18, 21, or as late as 25.6Social Security Administration. SI SF01120.205 – Uniform Gifts to Minors Act (UGMA) and Uniform Transfers to Minors Act (UTMA) When the transfer date arrives, the financial institution will need your child’s government-issued ID and the original account number to retitle it. At that point, your child can spend, invest, or withdraw every dollar.
Joint Bank Accounts
Joint custodial bank accounts, the kind most parents open for a teenager, usually need to be converted to an individual account or re-signed once the child turns 18. Your child will sign a new signature card and provide their own tax identification number. After that, you no longer have the legal right to view transactions or withdraw funds unless your child keeps you on as a joint holder by mutual agreement. If you want continued visibility for budgeting conversations, arrange it explicitly.
Credit Cards Before 21
Being 18 is not enough to open a credit card alone. Federal law prohibits issuers from opening an account for anyone under 21 unless the applicant demonstrates an independent ability to repay the debt or has a cosigner who is at least 21.7Office of the Law Revision Counsel. 15 U.S. Code 1637 – Open End Consumer Credit Plans A part-time job usually satisfies the independent-income requirement. A teenager with no income needs a parent or guardian to cosign, and a cosigner is fully liable for every charge. A lower-risk alternative is adding your child as an authorized user on your card. They can make purchases and often build credit history from the account, while only you remain legally responsible for the debt.
Taxes and FAFSA
For 2026, a single dependent must file a federal tax return if earned income exceeds the standard deduction of $16,100, or if unearned income exceeds a much lower threshold.8Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Most teenagers with part-time jobs earn well below $16,100, but filing is often worthwhile to claim a refund of withheld taxes.
Turning 18 does not end your ability to claim your child as a dependent. Under the qualifying child test, you can keep claiming a child who is under 19 at year-end, or under 24 if they are a full-time student, as long as they do not provide more than half of their own support and live with you for more than half the year.9Internal Revenue Service. Dependents 2 For most families with a college-bound 18-year-old, nothing changes on the tax front for several more years.
FAFSA uses a different definition. For the 2026–27 FAFSA, a student born after 2002 is generally considered dependent and must include parent financial information on the application, regardless of whether the parents actually claim the student on their taxes.10Federal Student Aid. 2026-27 FAFSA Form The only exceptions involve specific circumstances like marriage, military service, being a ward of the court, or legal emancipation. Moving out or paying your own rent does not make a student independent for FAFSA.
Selective Service, Voting, and Jury Duty
Selective Service
Male U.S. citizens and male immigrants between 18 and 25 must register with the Selective Service System within 30 days of their 18th birthday. Registration takes a few minutes online at sss.gov or can be done at a post office. Men on full-time active duty are exempt while serving continuously from 18 to 26, but National Guard and Reserve members not on full-time active duty must still register.11Selective Service System. Who Needs to Register
Failure to register is a federal felony punishable by up to five years in prison.12Office of the Law Revision Counsel. 50 USC 3811 – Offenses and Penalties Beyond the criminal penalty, men who fail to register become ineligible for federal student financial aid, federal job training, and most federal employment. After age 26, the window closes permanently. The law also requires registrants to report any address change within 10 days.13Selective Service System. Update Your Information
Voter Registration
At 18, your child becomes eligible to register to vote. Most jurisdictions allow registration online, at motor vehicle offices, or by mail. The process requires basic identifying information: legal name, date of birth, residential address, and a driver’s license number or partial Social Security number. Many states also let 16- and 17-year-olds pre-register, with registration becoming active on the 18th birthday.
Jury Duty
Your child also becomes eligible for jury duty at 18. Federal jury service requires U.S. citizenship, a minimum age of 18, at least one year of residency in the judicial district, and the ability to communicate in English.14United States Courts. Juror Qualifications, Exemptions and Excuses State courts have similar requirements. Potential jurors are drawn from voter registration rolls, driver’s license records, and other government databases. Ignoring a summons can result in fines or contempt of court.
Auto Insurance
Turning 18 does not automatically remove your child from your auto policy. As long as your child lives at home, most insurers will keep them as a listed driver. Full-time college students who take a family car to campus can usually stay on the parent’s policy as well. The real trigger for a separate policy is moving out permanently and establishing their own household.
Insurers generally require every licensed driver at the same address to be listed on the household policy, so a teen with a license should already be on yours. What changes at 18 is that your child can now purchase their own policy independently. Some families find a separate policy cheaper depending on the vehicles and driving records involved, so compare quotes both ways before switching.
New Adult Liability
The shift from juvenile to adult status in the criminal justice system is arguably the most consequential change. Offenses committed at 18 or older go through the adult courts, carry adult penalties, and create a permanent criminal record. Juvenile records are often sealed; adult records are not. A shoplifting charge that would have meant a diversion program at 17 could mean a misdemeanor conviction with lasting employment consequences at 18.
On the civil side, parental liability for a child’s negligent or harmful acts generally terminates at 18 in most states. If your 17-year-old causes a car accident, you might share financial responsibility; once they turn 18, that shifts entirely to them. Verify that your child has adequate auto and renters coverage before the birthday arrives.
Contracts work the same way. A minor can often void a contract they regret; an 18-year-old cannot. Apartment leases, car loans, cell phone agreements, and subscription services all become fully binding. Walking away from a lease or defaulting on a loan has financial consequences that can follow them for years, so your child should read every agreement before signing.