N-400 Mailing Address: Where to Send Your Application

Important: USCIS mailing addresses change periodically. Always verify the current address at uscis.gov before mailing your N-400. The addresses in this guide were accurate as of early 2026, but filing to the wrong address delays your case.

The N-400 mailing address you use depends on where you live, how you're filing, and whether you're a military member stationed overseas. USCIS operates multiple lockbox facilities, and the right address for your situation isn't always obvious. This guide walks you through the options and explains how to make sure your application goes to the right place.

Should You File Online or by Mail?

Before worrying about mailing addresses, consider whether you should mail your N-400 at all. USCIS strongly encourages applicants to file Form N-400 online through their myUSCIS account. Online filing offers several advantages:

• Faster processing — online submissions enter the queue more quickly
• Automatic confirmation of receipt
• Easier case tracking
• Reduced risk of lost or misdirected mail
• Ability to upload supporting documents digitally

If you're able to file online, do it. The mailing address question only applies if you can't file online due to specific circumstances — disability accommodations, certain fee waiver situations, or personal preference.

N-400 Mailing Addresses by State: USCIS Lockbox Locations

USCIS processes N-400 applications at two primary lockbox facilities. Your state of residence determines which facility receives your application. The correct N 400 mailing address depends on whether you're using regular USPS mail or a courier service (FedEx, UPS, DHL).

Phoenix Lockbox (Western States)

Applicants residing in Alaska, Arizona, California, Colorado, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, North Dakota, Ohio, Oregon, South Dakota, Utah, Washington, Wisconsin, Wyoming should mail to:

By U.S. Postal Service:
USCIS
Attn: N-400
P.O. Box 21251
Phoenix, AZ 85036-1251

By FedEx, UPS, or DHL:
USCIS
Attn: N-400 (Box 21251)
1820 E. Skyharbor Circle S, Suite 100
Phoenix, AZ 85034

Dallas Lockbox (Eastern States and Others)

Applicants residing in Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Mississippi, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Pennsylvania, Puerto Rico, Rhode Island, South Carolina, Tennessee, Texas, Vermont, Virginia, Washington D.C., West Virginia should mail to:

By U.S. Postal Service:
USCIS
Attn: N-400
P.O. Box 660060
Dallas, TX 75266-0060

By FedEx, UPS, or DHL:
USCIS
Attn: N-400 (Box 660060)
2501 S. State Highway 121 Business Suite 400
Lewisville, TX 75067

Military Applicants Outside the U.S.

If you're a member of the U.S. military or a dependent stationed outside the United States, you file under a different process. Military N-400 applicants may file with the USCIS Military Help Line or through JAG/legal assistance offices. The address and procedures are different — contact the nearest military legal assistance office or USCIS directly to confirm the correct process for your situation.

Fee Waiver Applications

If you're filing Form N-400 with a fee waiver request (Form I-912), the filing address may differ from the standard address. USCIS handles fee waiver packages separately in some cases. The safest approach is to use the address on the current USCIS instructions page for Form N-400, which specifies whether fee waiver applications go to the same lockbox.

What to Include in Your N-400 Package

Getting the mailing address right is only part of the job. If your package is incomplete when it arrives, USCIS will reject it and return it to you — adding weeks or months to your timeline.

A complete N-400 package typically includes:

• Completed Form N-400 (signed and dated)
• Filing fee of $725 (or fee waiver I-912 if applying for a waiver)
• Two passport-style photos (per USCIS specifications)
• Copy of your Permanent Resident Card (both sides)
• Supporting documents for any "yes" answers on the application (criminal history, travel, marriage, military service, etc.)

Review the N-400 Required Supporting Documents checklist before assembling your package. A missing document that's required based on your answers is a common cause of rejection or delays.

How to Mail Your N-400 Correctly

Don't just drop your N-400 in a regular mailbox. Use a method that provides proof of delivery — USPS Certified Mail with return receipt, Priority Mail with tracking, or an overnight courier service. You want documentation that your package arrived and the date it was received.

Keep copies of everything in your package. If USCIS loses your application or you need to inquire about processing status, you'll need your copies to reconstruct what you sent.

Use the correct envelope size. Your N-400 package — especially if you have supporting documents — can be thick. Use a large manila envelope or a sturdy flat-rate USPS envelope. Don't fold or staple the form itself.

After You Mail Your N-400

USCIS typically sends a receipt notice (Form I-797) within 2–3 weeks of receiving your application. The receipt notice confirms your application was received and gives you your receipt number, which you can use to check your case status online at uscis.gov or by calling the USCIS Contact Center.

If you don't receive a receipt notice within about 30 days of mailing, contact USCIS. It's possible your application was lost in transit, sent to the wrong address, or rejected and returned without notification. Having your certified mail tracking number is valuable here.

From receipt to interview scheduling, N-400 processing times vary significantly by field office. Some applicants are interviewed within six months; others wait over a year. Processing times fluctuate based on application volume, staffing, and policy priorities.

What If You Move After Filing?

If you move after mailing your N-400, you must notify USCIS of your address change. This matters for two reasons: USCIS will send your interview notice to your address of record, and failure to appear for your interview because you didn't receive the notice can result in denial.

To change your address, file Form AR-11 (Alien's Change of Address) online at uscis.gov, and also update your address specifically on your pending N-400 case through your myUSCIS account or by calling the USCIS Contact Center. The AR-11 alone doesn't always update your specific pending case.

N-400 Eligibility Before You File

The mailing address is the last step — before you get there, confirm you actually meet the eligibility requirements. Most applicants qualify under one of these paths:

• 5-year green card holder: Continuous residence of 5 years, physical presence for at least 30 months of those 5 years, and good moral character
• 3-year green card holder married to a U.S. citizen: Continuous residence of 3 years, physical presence for 18 months, still married and living with the citizen spouse
• Military service: Special rules apply for active duty military members and veterans

Review N-400 eligibility requirements carefully before filing. Filing before you're eligible wastes your filing fee and delays the process. USCIS won't refund your fee if you file prematurely and are denied.

Preparing for the Civics Interview

After USCIS processes your application and schedules your interview, you'll need to demonstrate English proficiency and pass a civics test. The civics test covers U.S. history and government — an officer will ask you up to 10 questions from the 100-question civics list, and you need to answer at least 6 correctly.

Start practicing for the civics test well before your interview. The N-400 Civics Test Preparation practice test covers all 100 official civics questions with explanations. Most applicants find the test manageable with focused preparation, but the interview itself can be nerve-wracking — the more familiar you are with the content, the more confident you'll feel.

Common N-400 Mailing Mistakes

A few mistakes come up repeatedly with N-400 filers that create unnecessary delays.

Sending to the wrong lockbox. If you live in California but accidentally mail to the Dallas address, your application gets rerouted — but this takes time and adds uncertainty. Check your state against the USCIS instructions carefully.

Using an outdated address from an old article or form. USCIS changes its lockbox addresses periodically. Always verify the current address directly at uscis.gov before mailing. Addresses printed in guides (including this one) become outdated when USCIS updates its procedures.

Mailing without delivery confirmation. A standard first-class letter to a P.O. box gives you no proof of delivery if something goes wrong. Use Certified Mail at minimum.

Incomplete packages. The most common cause of rejection is a missing required document or incorrect fee amount. USCIS won't call you to ask for the missing item — they'll return the package and you start over. Do a careful document check before sealing the envelope.

Not keeping copies. Your application gets processed at USCIS and you won't see it again until your interview. If questions arise — about a specific answer, a missing document, a discrepancy — you'll need your copies to remember exactly what you submitted.

Forgetting to notify USCIS of an address change. Moving after filing without updating your address means your interview notice goes to the wrong place. Missing your interview because you didn't receive the notice is a problem that's hard to fix after the fact.

The N-400 Timeline After Mailing

Understanding the timeline helps you know when to expect next steps and when to contact USCIS if something seems delayed.

After USCIS receives your package, their lockbox facility opens and reviews it for completeness. If accepted, they enter your application into the system and generate a receipt notice (Form I-797). You'll receive this in the mail within 2–3 weeks.

Your case then goes to the USCIS field office serving your address for interview scheduling. Wait times vary dramatically by location — some field offices schedule interviews within a few months; others have backlogs exceeding a year. The USCIS website publishes average processing times by form type and office, though these are approximations.

At your interview, an officer will review your application, test your English (through conversation unless you qualify for an exemption), and administer the civics test. If you pass, you may be scheduled for the oath ceremony the same day or receive a notice with a future ceremony date.

The full process from mailing to oath ceremony typically takes 8 to 18 months for most applicants, though times have ranged from under 6 months to over 2 years at different field offices during different periods. Starting your civics test preparation now — while you wait — means you'll be ready regardless of when your interview is scheduled.