Form N-400 Step by Step: How to Apply for US Citizenship

Every US naturalization starts with the same document: Form N-400, Application for Naturalization. It is long, and USCIS reads it closely. Most delays and denials come from things that could have been caught before filing: a residence period counted wrong, a trip abroad left off, a criminal record matter not disclosed.

This guide takes the process in order, so you know what each stage is for and what to have ready before you reach it.

Step 1: Confirm you are eligible

Most applicants qualify under the general rule. You need to:

• Be at least 18 years old when you file.
• Have been a lawful permanent resident (green card holder) for 5 years, or 3 years if you have been married to and living with a US citizen for that time and your spouse has been a citizen throughout.
• Have continuous residence for that period. A single trip abroad of more than six months can break it unless you can show you kept your ties to the US. A trip of a year or more almost always breaks it.
• Have physical presence in the US for at least half of the period: 30 months for the 5-year rule, 18 months for the 3-year rule.
• Have lived for at least 3 months in the state or USCIS district where you file.
• Show good moral character, which USCIS looks at mainly over the statutory period but can look beyond.
• Be able to read, write and speak basic English, and pass the civics test, unless an exemption applies.

Military service members and some spouses of citizens working abroad have separate rules. If any of these apply to you, read the specific USCIS guidance rather than the general rule.

Step 2: Use the 90-day early filing window correctly

You may file up to 90 days before you complete the required residence period. The date that counts is the "resident since" date on your green card. Count forward 5 years (or 3), then subtract 90 days. USCIS publishes an early filing calculator, and it is worth using rather than doing the arithmetic in your head.

An application filed too early is not held until you become eligible. It is denied, and the fee is not refunded.

Step 3: Gather your documents

The form asks for a lot of history, so collect it before you open it:

• Your green card (front and back copy for paper filing).
• Every address you have lived at during the statutory period, with dates.
• Your employment and school history for the same period.
• Every trip outside the US of 24 hours or more, with departure and return dates. Your passport stamps and airline records help here.
• Marital history, including previous marriages and how they ended, plus your spouse's citizenship evidence if you file under the 3-year rule.
• Information about your children.
• Certified court records for any arrest, citation or charge, even if it was dismissed or expunged. Traffic tickets under $500 generally do not need documents unless they involved alcohol or drugs, but read the instructions for your situation.
• Tax transcripts if there are any questions about whether you filed.

Honesty matters more than a clean record. Many past problems do not bar citizenship. Hiding one does, because false testimony is itself a good moral character problem.

Step 4: File and pay

As of 2026, the filing fee is $760 on paper or $710 online. A reduced fee of $380 applies if your household income is not more than 400 percent of the Federal Poverty Guidelines, and full fee waivers are available for qualifying applicants. Reduced-fee and waiver requests must be filed on paper with the supporting form.

Online filing through a USCIS account is the simpler route for most people. You upload evidence, receive notices electronically, and can see your case status without waiting for mail. After filing you receive a receipt notice (Form I-797C). Keep it: the receipt number is how you track your case.

Step 5: Attend biometrics

USCIS sends an appointment notice for an Application Support Center. The visit is short: fingerprints, a photo and a signature, used for the FBI background check. Bring the appointment notice and your green card. If USCIS can reuse biometrics from an earlier application, you may not be called in at all.

Step 6: Prepare for the interview

This is where most of your effort should go. The interview has three parts:

• Review of your N-400. The officer goes through your answers under oath and asks you to confirm or correct them. Review a copy of exactly what you filed before you go.
• The English test. Reading, writing and speaking. Speaking is assessed through the conversation itself. See our guide to the USCIS English test.
• The civics test. Which version you take depends on when you filed. If you filed before October 20, 2025, the officer asks up to 10 of the 100 questions and you need 6 correct. If you filed on or after that date, you take the 2025 version: up to 20 questions from a pool of 128, with 12 correct needed. Our comparison of the two versions explains the differences.

Applicants who are 65 or older and have held a green card for 20 years are exempt from the English requirement and take a shortened civics test drawn from 20 designated questions.

The civics test is oral. The officer reads the question aloud and you answer in your own words. Practise out loud, not just by reading. Our interview day guide covers what the room is like and how officers run it.

Step 7: Understand the decision

At the end, you receive Form N-652 with one of three results:

• Granted. You passed and the application is approved. Some offices hold a same-day oath ceremony; otherwise you get a notice with the date.
• Continued. USCIS needs more. Usually that means a retest of the part you failed, or more documents. A retest is normally scheduled within 60 to 90 days and covers only the part you did not pass.
• Denied. You receive a written explanation. You can request a hearing with Form N-336 within 30 days, or reapply later once the issue is resolved.

Step 8: Take the oath

You are not a citizen until you take the Oath of Allegiance at a ceremony. Our guide to the oath ceremony covers what to bring and what to do afterwards.

How long it takes

Times vary a lot by field office. As of 2026, many applicants wait 12 to 18 months from filing to the oath. USCIS publishes current processing times by office, and that is the figure to plan around rather than any general estimate.

Use the waiting time well. The civics test is the one part you fully control, and months of short daily practice beat a panicked final week every time.

Stika Studio builds CivicPass, a citizenship exam prep app with every official USCIS civics question, mock interviews and progress tracking. It also covers Canada, the UK, Germany, France, Spain, Sweden and Denmark.