Before you file Form N-400, you must meet the eligibility rules for naturalization. Most people qualify under either the 5-year or 3-year rule.
The 5-year rule (most applicants)
- Be a green card holder for at least 5 years
- Show continuous residence for those 5 years
- Be physically present in the U.S. for at least 30 months (half of 5 years)
The 3-year rule (spouses of U.S. citizens)
- Be a green card holder for at least 3 years
- Be married to and living with the same U.S. citizen for those 3 years
- Be physically present for at least 18 months
Requirements that apply to everyone
- Be at least 18 years old
- Have lived in your state or USCIS district for at least 3 months
- Show good moral character
- Pass the English and civics tests (with some exemptions)
- Take the Oath of Allegiance
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Counting your five years (or three)
Your period of permanent residence starts on the “Resident Since” date printed on your green card, which is the date your status was granted, not the date the card was mailed. You may file Form N-400 up to 90 days before the fifth (or third) anniversary of that date. Filing earlier than the 90-day window results in a denial, so count carefully and, if in doubt, wait a week.
Continuous residence versus physical presence
These are two separate tests. Continuous residence means you maintained your home in the United States for the whole period without an absence of six months or more (an absence of six months to a year creates a presumption you can rebut; one year or more breaks the period). Physical presence is simple arithmetic: you must have been physically inside the United States for at least 30 months out of the 5 years, or 18 months out of 3. Add up the days of every trip; a frequent business traveler can meet continuous residence and still fail physical presence.
The 3-year rule in detail
To use the 3-year rule you must, at the time of filing and until you take the oath: be married to a U.S. citizen; have been married to that same citizen for at least three years; have been a permanent resident for at least three years; and be living in “marital union” with your spouse, meaning you actually live together. Your spouse must have been a U.S. citizen for the entire three years. If you separate, divorce, or your spouse dies before the oath, you no longer qualify under this rule and must meet the 5-year rule instead. It does not matter how you got your green card; a person who obtained a green card through employment and later married a citizen can use the 3-year rule once three years of marriage and residence have passed.
The 3-month state or district requirement
You must have lived in the state, or the USCIS district, where you file for at least three months before filing. If you moved recently, wait until three months have passed at the new address. Students may file where they attend school or where their family lives if they are financially dependent on their parents.
Good moral character during the period
USCIS reviews the same 5-year or 3-year period for good moral character, although it can consider earlier conduct too. Certain convictions during the period, unpaid child support, false testimony to obtain an immigration benefit, failing to file taxes, and unlawful voting are common reasons for denial. Some offenses, such as murder and aggravated felonies, are permanent bars regardless of when they occurred.
Special categories
Current and former members of the U.S. armed forces, spouses of citizens employed abroad by the U.S. government or certain organizations, and some other categories have shorter or different requirements. If you think one applies to you, review the USCIS Policy Manual or speak with an attorney before filing under the standard rules.
A quick self-check
- Resident-since date plus 5 years (or 3), minus 90 days: is that date today or earlier?
- Any single trip of 6 months or more in the period?
- Total days outside the United States in the period under 913 (5-year) or 548 (3-year)?
- Three months at your current state or district?
- All tax returns filed; no unpaid child support; all arrests disclosed?
If every answer is yes, you are very likely eligible to file.
Last reviewed and expanded by the USCitizenTestPractice Editorial Team in September 2026, based on the USCIS Policy Manual, the official 2025 civics test materials, and current USCIS fee and form instructions. This is an independent study resource, not legal advice.
