How to apply for citizenship (Form N-400)
Studying for the civics test is only half the journey — first you have to actually apply, and that happens through one form: the N-400, the Application for Naturalization. It isn't complicated, but it's long, and a few small mistakes (wrong dates, a missed trip, an unpaid tax) cause most of the delays. Here's the whole process, start to finish, so you know what's coming.
First: are you eligible yet?
Most people apply after holding a green card for five years. If you're married to and living with a U.S. citizen, it's three years instead. You also need to be at least 18, have lived in the state or district where you apply for the last three months, and show “continuous residence” and “physical presence” — basically, that the U.S. has really been your home.
The trips are what trip people up. A single trip outside the U.S. of six months or more can break your continuous residence, and a trip of a year or more almost always does. You can apply up to 90 days before you hit your three- or five-year mark — many people file exactly then to start the clock sooner.
Filling out and filing the N-400
You can file online through a free USCIS account at my.uscis.gov, or mail a paper form. Online is easier to track and is what most people use now. The form asks about your background: where you've lived and worked, every trip outside the country, your marriage history, your children, and a long set of yes/no “good moral character” questions about arrests, taxes, and honesty on past immigration forms.
There's a filing fee, and USCIS offers a reduced fee or a full fee waiver for people with low income — check the current amount and the fee-waiver form on uscis.gov, since fees change. Answer everything truthfully; it's far better to disclose something and explain it than to have USCIS find it later.
Documents to gather
Have your green card and a state ID ready, plus a complete list of your trips outside the U.S. with dates. If they apply to you, gather tax transcripts, marriage or divorce certificates, anything about arrests or court records, and proof you've paid (or are paying) any taxes owed.
Pull your travel dates from your passport stamps and entry records before you start — reconstructing them later, under pressure, is where errors creep in.
Biometrics
After you file, USCIS usually schedules a short biometrics appointment to take your fingerprints and photo for a background check. Sometimes they reuse fingerprints you've already given and skip this step. Either way, there's nothing to study for — just show up with your appointment notice and ID.
The interview and the tests
Months later you'll get an interview appointment. The officer reviews your N-400 with you, gives you the civics test (spoken) and a short English reading and writing check, and confirms your answers are still true. This is the part this whole site prepares you for.
We cover the interview in detail in its own guide — what to bring, how the test is scored, and why the officer stops the moment you've passed.
The decision and the oath
At or after the interview you'll get one of three results: granted, continued (they need another document or a retake — common and usually harmless), or denied (rare at this stage). If you're granted, the last step is the Oath of Allegiance ceremony.
You're not a citizen until you take that oath. At some offices it's the same day as the interview; at others you get a separate date. When it's done, you'll receive your Certificate of Naturalization — and you can register to vote on the way out.
Forms, fees, and processing times change, so confirm every detail at uscis.gov before you file. But the path itself is steady: apply with the N-400, do your biometrics, pass the interview and tests, take the oath. Start studying the civics questions now, and the biggest part of the test will already be behind you.