The N-400 steps

What happens between sending your application and becoming a citizen.

1. Check that you qualify. Read who can apply and gather your documents: your green card, your travel history for the last 5 years, and your address and work history.
2. File Form N-400. You can file online through a USCIS account or by mail. The filing fee changes from time to time and some applicants qualify for a reduced fee or a fee waiver, so check the Form N-400 page for the current amount. If you file online, you upload copies of your documents. USCIS sends a receipt notice; its date decides which civics test you take.
3. Biometrics. If USCIS needs your fingerprints, photo or signature, it sends you an appointment notice with a date and place.
4. Interview and test. USCIS schedules an interview at a field office. An officer reviews your application with you and gives you the English and civics tests. See interview day.
5. Decision. USCIS sends a written notice. Your application may be granted, continued (USCIS needs more documents, or you need to retake a test), or denied.
6. Oath of Allegiance. You become a U.S. citizen when you take the oath at a ceremony, not before. You hand in your green card and receive your Certificate of Naturalization.

If you do not pass a test

You get two chances. If you fail the English test or the civics test at your first interview, USCIS gives you another appointment, between 60 and 90 days later, to retake only the part you did not pass. If you fail that part again, the application is denied and you would need to apply again.

How long it takes

It varies by field office and changes over time. Look up your office on the USCIS processing times page, and follow your own case in your USCIS online account.

Source: USCIS, 10 Steps to Naturalization.