When you turn 18 in California, you become a legal adult under Family Code § 6500, and parental authority over your decisions ends by default. You can vote, sign binding contracts, consent to your own medical care, control your school records, and marry without permission. You can also be prosecuted as an adult, sued in your own name, and required to file taxes on what you earn. A handful of things still wait until 21, including tobacco, alcohol, cannabis, and most firearms.
Vote, Serve on Juries, and Register with Selective Service
You can register to vote once you turn 18 if you’re a U.S. citizen, a California resident, and not currently imprisoned for a felony. Registration goes through the Secretary of State’s online portal or a paper form sent to your county elections office.1California Legislative Information. California Elections Code 2101
Registering also puts you in the jury pool. California pulls prospective jurors from voter rolls and DMV records, so expect a summons at some point.2California Legislative Information. California Code of Civil Procedure 190-237 Jury service is treated as an obligation, not an invitation.
If you’re male, federal law requires you to register with the Selective Service System within 30 days of your eighteenth birthday. This covers U.S. citizens, permanent residents, undocumented immigrants, refugees, and most other male immigrants between 18 and 25. The only males exempt are those on current, valid non-immigrant visas. Skipping registration can permanently cut you off from federal student aid, federal employment, and security clearances.3Selective Service System. Who Needs to Register
You’re Now Prosecuted as an Adult
California’s juvenile court handles offenses committed between ages 12 and 17. The day you turn 18, any crime you commit is charged in adult court, with adult sentencing available.4California Legislative Information. California Welfare and Institutions Code 602 That means county jail or state prison rather than juvenile hall, a permanent adult criminal record rather than a sealed juvenile file, and convictions that can follow you into housing, employment, and professional licensing for life. Most new adults don’t think about this shift until it’s too late.
Sign Contracts, Open Accounts, and Rent in Your Own Name
As a minor you couldn’t enter contracts involving real property or personal property outside your immediate possession. Those restrictions lift at 18.5California Legislative Information. California Family Code 6701 – Capacity to Contract You can sign an apartment lease, take out a car loan, agree to a cell phone contract, or open a bank account in your own name without a parent as joint owner. Every signature carries full legal weight, and defaults can trigger lawsuits and credit damage.
Credit cards are the exception. A federal rule requires card issuers to verify that applicants under 21 have independent income sufficient to make minimum payments. If you can’t show that income, you’ll need a cosigner who is at least 21.6eCFR. 12 CFR 1026.51 – Ability to Pay Landlords often ask for gross monthly income of at least three times the rent, which is tough for a new worker; a cosigner or guarantor can bridge the gap.
Sue and Be Sued on Your Own
At 18 you can sue someone in your own name and be sued in yours. A guardian ad litem is no longer needed to represent you. If you’re served with a summons and complaint, you have 30 days to file a response. Miss that deadline and the other side can ask the court to enter a default judgment, meaning you lose without ever being heard.7Judicial Branch of California. Summons (form SUM-100) and Complaint Ignoring legal paperwork is one of the most expensive mistakes a new adult can make.
Take Any Job, Any Hours
Federal labor law bars workers under 18 from hazardous jobs, including operating heavy machinery, roofing, demolition, mining, handling explosives or radioactive materials, and driving commercial vehicles. On your eighteenth birthday, those restrictions disappear.8U.S. Department of Labor. FLSA – Child Labor Rules California’s work-hour limits and work permit requirements for minors also stop applying. You can work any number of hours, at any time of day, in any lawful occupation.
Make Your Own Medical Decisions
You become the only person who can consent to or refuse your own medical treatment. Parents lose the automatic right to view test results, access records, or schedule appointments for you. California’s Confidentiality of Medical Information Act bars healthcare providers from disclosing your medical information without written authorization.9California Legislative Information. California Civil Code 56.10 Federal HIPAA rules reinforce this limit for covered entities handling adult patient information.10U.S. Department of Health & Human Services. Summary of the HIPAA Privacy Rule
This matters most in emergencies. If you’re in an accident and can’t communicate, doctors may not be able to discuss your condition with your family unless you’ve set things up in advance. Signing a healthcare power of attorney that names someone to make decisions on your behalf during incapacity is one of the smartest early moves, along with updating emergency contacts and privacy forms at your doctor’s office. You can also register as an organ, eye, and tissue donor on your own; before 18, a parent held the final say.
Control Your School Records
The Family Educational Rights and Privacy Act transfers control over your educational records from your parents to you at 18. Your high school can no longer release grades, disciplinary records, or other school information to your parents without your written consent, and the same rule covers college enrollment at any age.11Protecting Student Privacy. Eligible Student
One exception: if your parents still claim you as a dependent on their federal tax return, the school may share records with them without your consent.11Protecting Student Privacy. Eligible Student If you want your parents to see your college grades or financial aid status and that exception doesn’t apply, most schools offer a FERPA waiver form specifying which records can be shared, with whom, and for what purpose.12U.S. Department of Education. Protecting Student Privacy: FERPA
File Your Own Taxes
Turning 18 doesn’t automatically trigger a tax filing requirement. Earning money does. For the 2026 tax year, the standard deduction for a single filer is $16,100.13Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 If your gross income exceeds that amount, you’re generally required to file a federal return. Even if you earn less, filing is worthwhile if your employer withheld taxes and you’re owed a refund.
Your parents may still claim you as a dependent after 18. The IRS allows it if you’re under 19 at the end of the tax year, or under 24 as a full-time student, and you meet the residency and support tests. If you’re not a student and turn 19 during the year, you can still be claimed as a qualifying relative, but only if your gross income is less than $5,200.14Internal Revenue Service. Publication 501 – Dependents, Standard Deduction, and Filing Information Being claimed as a dependent doesn’t stop you from filing your own return; it just means you can’t claim yourself.
Marry, Get Tattooed, Change Your Name, Write a Will
Two unmarried people who are 18 or older can marry in California without a court order or parental consent, after applying for a license at the county clerk’s office.15California Legislative Information. California Family Code 301
Penal Code § 653 makes it a misdemeanor to tattoo someone under 18, and that prohibition lifts on your birthday. Any licensed shop can then tattoo you.16California Legislative Information. California Penal Code 653
You can petition superior court for a legal name change or gender marker update. Filing fees run $435 to $450 depending on the county, with waivers available if you can’t afford it. Name changes tied to gender identity don’t require newspaper publication.17California Courts. Change Your Name in California
Anyone 18 or older and of sound mind can create a valid will in California.18California Legislative Information. California Probate Code 6100 Most 18-year-olds skip this, but if you own a car, have savings, or want someone named to handle your affairs, a basic will and healthcare directive are worth putting in place.
What You Still Can’t Do Until 21
California raised its minimum tobacco purchase age to 21 for cigarettes, vaping products, and all other tobacco products. The only exception is active-duty military personnel who are 18 or older.19California Department of Public Health. California Tobacco 21 Law Alcohol and cannabis both carry a minimum purchase and consumption age of 21.
Firearms are tightly restricted. California generally prohibits the sale, loan, or transfer of any firearm to a person under 21, with limited exceptions for law enforcement and military.20California Attorney General. Overview of Key California Firearms Laws This is stricter than federal law, which allows 18-year-olds to buy long guns in most other states.
Gambling splits by venue. You can buy lottery tickets and bet on horse races at 18, but commercial casinos and most card rooms require 21. Tribal casinos vary; some admit 18-year-old patrons, others set the floor at 21. And as covered above, credit card issuers must see proof of your own income or a cosigner before approving an account under 21.