Form N-400, Application for Naturalization, is the official document that starts your journey to U.S. citizenship.

It is 20 pages long (14 parts) and can be intimidating. However, by following this step-by-step guide, you will avoid common errors that cause delays or denials.

This article explains every section, required evidence, and submission strategies.

Before You Begin: Check Your Eligibility

Do not file N-400 unless you meet the 3 or 5-year rule, physical presence, and continuous residence requirements (see previous article).

Filing too early results in automatic denial and lost fees.

Part 1: Your Name and Information

  • Write exactly as shown on your Green Card. If you legally changed your name (marriage, court order), attach proof.
  • Provide your A-Number (Alien Registration Number) – it starts with 'A' followed by 8 or 9 digits.
  • USCIS Online Account Number? Leave blank if you don't have one.

Part 2: Basis for Eligibility

Select the correct box. Most common:

  • Box A: LPR for 5+ years (general).
  • Box B: LPR for 3+ years and married to same U.S. citizen for 3+ years.
  • Box C or D: Military service (different forms apply for some).
Critical mistake: Spouses who are separated or divorced must file under Box A (5-year rule), not Box B. If your spouse passed away, you may still qualify under Box B if you were married for 3+ years.

Part 3: Biometrics and Contact Info

Provide a valid mailing address. USCIS will send biometrics appointment, interview notice, and Oath Ceremony invitation to this address.

Use a safe, monitored mailbox (not a shared office). For email, check spam folders weekly.

Part 4: Information About Your Residence and Travel

Two critical sections:

  1. Residences for last 5 years (or 3 years): List every address, even if you moved across the street. Include exact months and years. Gaps of more than a few days will raise questions.
  2. Trips outside the U.S. for last 5 years: Provide all departures and returns. For frequent travelers (e.g., cross-border workers), attach a separate sheet. USCIS will compare your list to your I-94 records.

Use a travel calculator (many free online tools) to compute your physical presence days.

Round up? No. Be precise.

Part 5: Information About Your Parents

Even if your parents are not U.S. citizens, answer fully. USCIS uses this for administrative records and possible derivative claims.

Part 6: Employment and Schools

List all jobs and schools for the last 5 years. Unemployed?

Write 'Unemployed' with dates. Gaps longer than 6 months should be explained in Part 14 (Additional Information).

Retired? Write 'Retired' and previous employer.

Parts 7–10: Good Moral Character (GMC)

These are the most important parts. USCIS asks about arrests, crimes, false claims to U.S. citizenship, voting illegally, prostitution, terrorist activity, and failing to pay child support.

Rule of thumb: When in doubt, disclose. Do not say 'no' if you were ever cited, arrested, or charged – even if the case was dismissed or sealed. Non-disclosure is a separate ground of denial (lying under oath).

Attach certified court dispositions for every arrest, no matter how minor (including expunged records).

If you have no documentation, request them from the courthouse before filing.

Part 11: Selective Service Registration

Males between 18 and 26 (inclusive) must register with Selective Service. If you were required but did not register, USCIS will deny your N-400 unless you provide a status letter from Selective Service proving you were not required (e.g., non-immigrant visa status during that period).

If you are over 31, answer 'YES' and explain you registered.

Part 12: Oath of Allegiance

Affirm that you will bear arms or perform civilian service if required. Only answer 'no' if you seek a religious exemption (must be documented).

Part 13: Signature

Sign and date. If a preparer helped you (lawyer, family member), they must also sign Part 14.

Part 14: Additional Information

Use extra sheets to explain any 'yes' answers to criminal or moral character questions, or to clarify travel gaps.

Write 'See attachment A' clearly.

Required Evidence to Include

  • Copy of both sides of your Green Card.
  • Copy of any marriage certificates, divorce decrees, or death certificates (for spouse cases).
  • Copy of court dispositions (if any arrest).
  • Form N-648 (medical waiver) if claiming English exemption.
  • Two passport-style photos (only if filing by mail; online filing does not require photos upfront).

Filing Fees and Where to Send

Current fee: $710 (includes $640 application fee + $70 biometrics). Reduced fee ($405) may be available if household income is below 200% of poverty guidelines.

Fee waivers (N-912) are rare for naturalization.

File online (recommended) via my.uscis.gov – faster confirmation and fewer errors. Or mail to the Phoenix or Dallas lockbox depending on your state.

Pro tip: After filing, you will receive Form I-797 receipt notice within 4 weeks. Then biometrics (about 4-8 weeks later), then interview (6-12 months after that). Track your case at egov.uscis.gov.

Double-check every answer. A single wrong date or omitted trip can lead to an RFE (Request for Evidence) or denial.

Good luck!