What form do you use to apply for citizenship?

Form N-400, the Application for Naturalization, is the form a lawful permanent resident uses to apply to become a U.S. citizen. The form is published and processed by U.S. Citizenship and Immigration Services (USCIS), the agency within the Department of Homeland Security responsible for adjudicating immigration benefits. The current edition of Form N-400 is 20 pages long and is divided into 18 parts, covering the applicant's biographical information, residence and employment history for the past five years, marital and parental history, time outside the United States, military service, criminal history, allegiance and good moral character questions, English and civics test eligibility, and accommodations requests.

The form is available free of charge on the USCIS website at uscis.gov/n-400, in English, and may be filed either by mail to a USCIS Lockbox or electronically through a USCIS online account at my.uscis.gov for most applicants. Mailing addresses depend on the applicant's state of residence and are listed in the form instructions.

Filing requires the applicant to submit the completed form, the filing fee (currently $710 for online filing or $760 for paper filing under the fee schedule effective April 1, 2024, which combined the previous $640 form fee and $85 biometric fee), two passport-style photos if filing from outside the United States, a copy of the front and back of the applicant's Permanent Resident Card (Form I-551, also called the green card), and supporting documents specific to the applicant's eligibility category (for example, marriage certificates, divorce decrees, court records, military service records, or tax records).

The form replaces an older form, the N-405, used before 1991. Form N-400 was substantially revised by USCIS most recently in April 2024 to align with the current fee structure and the 128-question civics test (USCIS announced in late 2024 that the redesigned 2025 civics test, originally proposed in 2020, would be implemented gradually). USCIS adjudicates approximately 800,000 to 1 million N-400 applications per year, with average processing time around eight to twelve months from filing to oath ceremony. The N-400 is the gateway document of the entire naturalization process and is governed by section 334 of the Immigration and Nationality Act (8 U.S.C. section 1445).