What changes legally when you turn 18, and what to do in that first week

How to read the age-18 table

Each row is one thing that flips on your birthday. The middle column is the rule in plain words. The last column is the grade the book gives it.

Every row here is an A. That means a law or an official rule sits behind it, not just someone's opinion. On this page we kept it that way on purpose, so you can tell what is required and what is only good advice.

Two rows need a date in your calendar. Men have 30 days for Selective Service. And the health care proxy only works if you sign it before you need it.

The Cornell Law School page on the age of majority explains the idea of legal adulthood if you want the longer version.

Adult means 19 or 21 in a few states

Most states say adult starts at 18. Not all. Alabama and Nebraska use 19, and Mississippi uses 21.

And adult is not one switch. The drinking age is 21 everywhere. The voting age is 18. The driving age is its own rule. So in the same state, you can be an adult for a lease and still a minor for a beer.

Spend two minutes on your own state's rule. It costs nothing, and you will know which choices are now yours alone.

The quiet change at the doctor's office

This is the one most families miss. When you were a minor, your parents could usually see your medical records and make choices for you. At 18 that stops.

If you are in a crash or too sick to talk, nobody can speak for you unless you named them. The fix is two forms: your state's health care proxy and a HIPAA authorization. Most states need witnesses or a notary. Your state health department, attorney general or state bar usually posts the free form. In New York, any adult 18 or older can name an agent on a free state form with two adult witnesses.

The HHS page on personal representatives lays out the federal side. The book gives this move an A and puts it on its short list of Cheap A's.

Registering, voting and the summons in the mail

Voting comes first. You register through vote.gov, which sends you to your state's own site. It takes five to fifteen minutes in most states. Many states let you pre-register at 16 or 17.

If you are a man, you also register with Selective Service. It is not joining the military. Our page on missing the Selective Service deadline covers what to do if your 30 days already passed.

Then one day a jury summons may show up. Read it and answer by the date on it. Federal jurors are paid $50 a day. A real court reaches you by mail. A call saying you missed jury duty and must pay a fine is a scam.

It is the night before your birthday

Your phone is full of messages. Someone ordered a cake. Nobody has said a word about forms.

Tomorrow you can sign a lease. You can sign up for a phone plan on your own. If you end up in the hospital, the doctor may not be able to call your mom and talk it through. None of that comes with a warning.

That is the whole point of a first-week list. The changes are quiet, so you have to go looking for them.

The chapters that handle turning 18

This is the problem The 18 Manual was written for. Iris Athens wrote it as the letter nobody sends.

The Week You Turn 18 walks through eight moves: your state's age of majority, reading every contract, voting, Selective Service, jury duty, the fake jury fine call, the health care proxy and REAL ID. Each one lists its cost and its proof grade.

The Cheap A's is one page of the moves that cost close to nothing and have the strongest proof. Start there if you only have one afternoon.

Legal Red Lines at 18 covers what changes on the other side: adult court, the federal photo laws that apply to anyone under 18, and threats posted as a joke.

The book explains published rules. It is not legal advice. For your own state's rules, check your state's court self-help site, and for a real problem, legal aid at LawHelp.org is free if you qualify.