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US Citizenship Requirements: Who Can Apply for Naturalization
By David N. Smith, TGM, Athens, Greece
Last reviewed: October 21, 2026
Short answer: Most applicants must be at least 18, have been a lawful permanent resident for five years (three if married to and living with a US citizen), have lived continuously in the United States for that period, have been physically present for at least half of it, have lived in their state for three months, show good moral character, pass English and civics tests, and support the Constitution.
The rules come from the Immigration and Nationality Act (INA) and USCIS regulations. They look long, but each one answers a simple question about your ties to the United States. This guide explains each requirement, how time is counted, and where the rules differ for marriage and military applicants.
The standard path at a glance
| Requirement | General rule | Marriage to a US citizen |
|---|---|---|
| Age | 18 or older when you file | 18 or older |
| Permanent resident status | 5 years | 3 years, married to and living with a US citizen the whole time |
| Continuous residence | 5 years | 3 years |
| Physical presence | At least 30 months in the US | At least 18 months |
| State or district residence | 3 months before filing | 3 months |
| Good moral character | Throughout the statutory period (5 years) | Throughout the period (3 years) |
| English, civics and Constitution | Yes, unless an exception applies | Yes |
These come mainly from 8 U.S.C. §§ 1427 (the five-year rule) and 1430 (the marriage rule). You may be able to file up to 90 days before you reach the required residence period.
1. Lawful permanent resident status
You must hold a green card for the required time. The clock generally starts on the date your permanent residence began, as shown on the card. Keep your card valid, because you will need it for your biometrics and interview.
2. Continuous residence
You must have lived continuously in the United States during the statutory period. Trips abroad do not automatically break this, but length matters:
- Under six months: generally no problem.
- Six months to under one year: USCIS presumes continuity was broken. You can overcome the presumption with evidence, such as keeping your job, home, family and taxes in the United States.
- One year or more: continuity is broken. You usually have to wait and start a new period, unless an exception applies.
Certain people working abroad for the US government, some American companies and institutions, or religious organizations may preserve continuous residence by filing Form N-470 before the trip.
3. Physical presence
Physical presence counts the actual days you spent inside the United States. You need at least half of the statutory period: 30 months (5-year rule) or 18 months (3-year rule). Every day abroad counts, including travel days. Keep a travel log and old passports to prove your dates.
4. State or district residence
You must have lived for at least three months in the state or USCIS district where you file. Proof can be a lease, mortgage, utility bill, state ID or pay stubs. If you move shortly before filing, wait until you meet the three months.
5. Good moral character (GMC)
GMC means more than "no crimes." It is the standard behavior of a person who respects the law and community. The law lists conduct that bars a finding of good moral character, such as certain serious crimes, and conduct that can lead to a negative finding, such as unlawful voting or false claims to citizenship. It covers the full statutory period and the time until you take the oath.
What changed in 2025. In August 2025, USCIS issued policy memos that, according to law-firm and legal-aid summaries, shifted officers toward a "totality of the circumstances" review. Officers may weigh positive factors, such as community involvement, caregiving, education, steady work, tax compliance and long lawful residence. They may weigh negative factors such as repeated serious traffic offenses, harassment, drug offenses or unlawful voting. USCIS also resumed neighborhood investigations, where officers may contact people who know you to confirm residence, employment and character. The details of how offices apply these memos are still developing, so ask an attorney about your own facts.
Practical points
- Answer every question on the N-400 honestly. Lying to USCIS can itself destroy GMC and can lead to criminal charges or denaturalization.
- Pay taxes and court-ordered obligations such as child support.
- If you have any arrest, citation or conviction, even old or expunged ones, talk to an attorney before filing.
- Never claim to be a citizen or register or vote before you are one.
6. Attachment to the Constitution
You must show that you are "attached to the principles of the Constitution" and well disposed to the good order of the United States. In practice, officers test this through your N-400 answers, your conduct, and your willingness to take the oath. The oath itself includes this promise; see our oath guide.
7. English and civics
You must read, write and speak basic English and pass a civics test on US history and government. Read how the tests work in the civics test guide. Some older long-term residents and applicants with disabilities are exempt or get special consideration; see test exceptions.
8. Selective Service
Men who lived in the United States between the ages of 18 and 25 generally must have registered with the Selective Service System. USCIS asks about it on the N-400. If you did not register when required, get legal advice before filing.
Special categories
Military service. Under INA §§ 328 and 329, people who served honorably in the US armed forces can naturalize under reduced or waived requirements, and are exempt from the filing fee. Peacetime service (one year) and service during periods of hostilities have different rules. Officers decide what counts as honorable service.
Spouses of service members. A spouse who lives abroad with a US service member stationed overseas may be able to naturalize under special provisions.
Citizenship through a parent. Children under 18 may already be citizens by acquisition or derivation. They do not file Form N-400. They can request a certificate of citizenship using Form N-600.
Requirements by category
| Category | Green card | Continuous residence | Physical presence | State residence | Good moral character |
|---|---|---|---|---|---|
| Standard (LPR) | 5 years | 5 years | 30 months | 3 months | 5 years |
| Marriage to US citizen | 3 years | 3 years | 18 months | 3 months | 3 years |
| Military, peacetime (§ 328) | Required at filing | Reduced or exempt in some cases | 30 months, or waived while serving | Exempt | 5 years |
| Military, hostilities (§ 329) | Required at filing or enlistment | Exempt | Exempt | Exempt | 1 year |
These rows summarize the law; details and exceptions are in the INA and the USCIS Policy Manual.
Dual citizenship
US policy lets you keep a second nationality after you naturalize. Some other countries do not allow dual citizenship, so check your home country's rules before you apply.
A quick self-check
- Am I 18 or older?
- Have I held my green card for five years (or three, as a spouse of a citizen)?
- Have I lived continuously in the US, with no trip of six months or more?
- Have I spent at least half of that time physically in the US?
- Have I lived in my state for three months?
- Can I truthfully say I have no unresolved criminal, tax, voting or immigration problems?
- Can I read, write and speak basic English, or do I qualify for an exception?
If any answer is "no" or "not sure," speak to a legal-aid provider before paying the filing fee. If every answer is "yes," continue with the step-by-step process.
Frequently asked questions
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Usually five years. If you have been married to and living with a US citizen for three years, and your spouse has been a citizen for that time, you can apply after three years.
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Yes, up to 90 days before you complete the required period of permanent residence, if you meet all other requirements.
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It can. Trips under six months usually do not break continuous residence. Trips of six months to a year raise a presumption that you broke it. A year or more breaks it. Total days abroad also affect physical presence.
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Yes, basic English, unless you qualify for an exception based on age and years as a permanent resident or a medical disability. See test exceptions.
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It depends on the offense, how long ago it happened and what the record shows. Some crimes permanently bar naturalization; others can be overcome with time and evidence. Consult an attorney before you file.
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The United States does not require you to give it up. Your other country's law decides.
Sources and further reading
- 8 U.S.C. § 1427: requirements of naturalization; 8 U.S.C. § 1430: spouses of citizens
- 8 U.S.C. § 1423: English and civics requirements
- USCIS Policy Manual, Volume 12: Citizenship and Naturalization
- USCIS, Learn About Citizenship and Form N-470
- Immigrant Legal Resource Center, Naturalization alert: memos on good moral character and neighborhood visits
- Duane Morris LLP, client alert on USCIS naturalization policy changes, October 2025
- Citizenshipworks
This page is general information, not legal advice. Naturalization rules and USCIS policy change. Consult a licensed attorney or accredited representative about your situation. We are not affiliated with USCIS or any government agency. Last reviewed October 21, 2026.