Apply for U.S. citizenship through naturalization

Confirm that naturalization is the correct path

Some people may already be U.S. citizens through a parent or may qualify under military or other special rules. Before filing N-400, check whether you need a citizenship certificate, passport evidence, or a different naturalization route.

Choose the eligibility basis

The most common routes are based on five years as a lawful permanent resident or three years as a lawful permanent resident while married to and living in marital union with a U.S. citizen. Different rules may apply to military members, certain spouses employed abroad, and other special categories.

Five-year route: generally requires age 18 or older, at least five years as a lawful permanent resident, continuous residence, at least 30 months of physical presence during the five-year period, and at least three months of residence in the state or USCIS district before filing.
Three-year spouse route: generally requires age 18 or older, at least three years as a lawful permanent resident, three years of marriage to and marital union with the same U.S. citizen spouse, at least 18 months of physical presence during the three-year period, and the applicable local-residence requirement.

Review travel before filing

List every trip outside the United States during the relevant statutory period. Absences of more than six months may raise continuous-residence questions, and an absence of one year or more can generally break continuous residence unless a specific preservation rule applies. Physical presence is a separate day-count requirement.

Review the full personal history

Form N-400 asks about addresses, employment or school, family, taxes, Selective Service, organizations, immigration history, arrests and citations, and other conduct. Answer accurately even when a record was sealed, expunged, dismissed, or occurred outside the United States if the form or instructions require disclosure. Complex criminal, immigration, tax, or travel history can affect eligibility; qualified legal advice may be appropriate before filing.

Prepare and submit Form N-400

USCIS accepts eligible N-400 filings online and by mail. Use the current form page to verify the accepted edition, filing address, fee, reduced-fee or fee-waiver options, and required evidence on the day you file. Keep a complete copy and the receipt number.

Complete the case steps

USCIS accepts the filing and issues a receipt notice.
USCIS may schedule biometrics or reuse previously collected biometrics.
You attend a naturalization interview and answer questions under oath.
You complete the required English and civics testing unless an exception or accommodation applies.
USCIS issues a decision or requests additional evidence.
If approved, you attend a ceremony and take the Oath of Allegiance. You do not become a U.S. citizen until the oath is administered.

Use the correct civics test materials

USCIS states that applicants who filed Form N-400 on or after October 20, 2025 take the 2025 civics test. Applicants who filed before that date generally take the 2008 civics test. Confirm the test version shown for your filing date and study only current USCIS materials.

Civil or nationality paperwork in another country

Naturalization in the United States does not replace civil-record, nationality, or consular procedures required by another country. See the country-specific guidance for the United States, Spain, and Argentina before starting a separate process abroad.