How to apply for US citizenship: the N-400, step by step

Naturalization is the one immigration process that most applicants complete without a lawyer, and USCIS writes for that reader: the form page, a ten-step guide and a study site for the test. This page follows the same sequence and takes each figure from those documents or from the agency's Policy Manual. Nothing here is legal advice; where a case has a complication, such as a long absence, an arrest or an unpaid tax, the Policy Manual chapter linked at that point is where the rule lives.

Who can apply

The general rule, in the Policy Manual's chapter on continuous residence, is five years as a lawful permanent resident before filing, counted from the date on the green card, and continuing to the day of naturalization. Spouses of US citizens who have been married and living with the citizen for three years, where the citizen has held citizenship for those three years, may file after three years. Either way the application may be filed up to 90 days before the anniversary, and the applicant must have lived for at least three months in the state or USCIS district where it is filed. Applicants must be at least 18.

Continuous residence is about where your life is, not just where you are. The manual says an absence of more than six months but less than a year is presumed to break it unless the applicant shows otherwise, with evidence such as a job, a home and family that stayed in the United States. An absence of a year or more breaks it outright, and the clock largely restarts: someone under the five-year rule must then wait four years and one day after returning before filing. Separately, the physical presence rule requires that the applicant was actually inside the United States for at least half the period: 30 months, which the manual states as at least 913 days, under the five-year rule, and 18 months under the three-year rule. Trips abroad count against physical presence even when they do not break residence, so the travel history on the form has to be complete and truthful.

The remaining requirements are good moral character during the period, attachment to the Constitution, and the ability to read, write and speak basic English and to pass a civics test, with the exceptions described below.

What it costs

The fee schedule sets the N-400 at $760 for a paper filing and $710 for an online filing. Applicants whose household income falls in the reduced-fee band set out in the form instructions pay $380 and attach proof of income. Those who qualify for a full fee waiver file Form I-912 and pay nothing. The form page is explicit on one point: a reduced-fee or fee-waiver application cannot be filed online and must go in on paper. The form edition in use is dated 01/20/25, and a paper filing on an older edition is rejected.

The steps, and how long each takes

USCIS's own guide breaks the process into ten steps. In practice five of them are events on a calendar.

Filing. Online filing through a USCIS account gives an immediate receipt and lets you upload evidence and see notices; a paper filing goes to the lockbox address for your state and produces a receipt notice by mail. The receipt notice carries the receipt number you will use to check status, and it names the field office that will handle the case.

Biometrics. Most applicants are scheduled for fingerprints and a photograph at an application support center, though USCIS reuses prints it already holds for many applicants and waives the appointment. The notice gives the date and place.

The interview. This is the decision meeting. An officer reviews the application question by question under oath, administers the English and civics tests, and asks about travel, taxes, arrests and anything that changed since filing. Bring the interview notice, the green card, every passport covering the period, and originals of anything submitted as a copy. The wait between filing and interview is the processing time USCIS publishes for your office; FactFiled lists every office on N-400 processing times by field office, and in the data through July 2026 the median office was 11.5 months, from 8 in Cincinnati to 17.5 in Lawrence, Massachusetts. USCIS processing times, explained covers what that figure does and does not mean.

The decision. USCIS mails a notice of decision, and online filers see it in their account. An application can be granted, continued if evidence is missing or a test was failed, or denied. A denial can be challenged with a hearing request on Form N-336.

The oath. Citizenship begins when the oath of allegiance is taken at a ceremony, not when the application is approved. Some field offices hold the ceremony on the day of the interview; otherwise a notice follows with a date, usually within weeks. The Certificate of Naturalization is handed over at the ceremony and should be checked for errors before leaving.

The tests

The English test has three parts, all given at the interview. Speaking is assessed through the interview itself. For reading, USCIS's test page says you must read one of three sentences correctly; for writing, you must write one of three sentences correctly. The vocabulary for both is published.

The civics test depends on the filing date. Applications filed on or after October 20, 2025 take the 2025 test, which the page describes as an oral test of 20 questions from a published list of 128; 12 correct answers pass, and the officer stops asking at the twelfth correct or the ninth wrong answer. Applications filed before that date take the 2008 test: 10 questions from a list of 100, with 6 correct needed. Under the Policy Manual's testing chapter, an applicant who fails any portion is rescheduled for a second examination 60 to 90 days later and is retested only on the portion failed; a second failure requires the officer to deny the application.

Age and time in the country change the requirements. Under the same chapter, an applicant aged 50 or older who has been a permanent resident for at least 20 years, or 55 or older with at least 15 years, is exempt from the English requirement and may take the civics test in their own language with an interpreter. An applicant aged 65 or older with at least 20 years as a permanent resident gets special consideration on civics: a shorter test drawn from a designated list. A medical disability that prevents learning English or civics can be documented by a doctor on Form N-648 for an exception to either test or both.

Before you file

Three things account for most of the trouble at interview, and all three are checkable in advance. Count the days abroad from passport stamps and airline records and compare them with the six-month and one-year thresholds. Confirm that tax returns were filed for every year of the period, and that any tax owed is paid or on a payment plan, because the officer asks. And list every arrest or citation, however minor and however long ago, because the question is asked under oath and an omission is treated more seriously than the event.

The A-Number explainer covers the file number the form asks for on its first page, and What a Request for Evidence means covers the notice USCIS sends when something is missing.