Many applicants preparing for U.S. naturalization need clear guidance on where to send the N-400 form and supporting documents. This overview helps you choose the correct address and avoid processing delays.
Use the summary below to quickly understand which service center handles your situation and what documents to include.
| Address Type | Location | When to Use | Required Supporting Documents |
|---|---|---|---|
| Lockbox (Austin) | 102 N Queen St, Austin, TX 78701 | Online or paper filing in most U.S. states | Completed N-400, fees, photos, evidence |
| Direct Service Center | Varies by region (e.g., Phoenix, Chicago) | Fingerprint appointment scheduled with form | N-400, appointment notice, ID, photos |
| USCIS Intake Facility | 131 Piner Street, Santa Rosa, CA 95403 | Applicants in California using paper or specific circumstances | N-400, fees, biometric appointment letter if applicable |
| Regional Lockbox | Denver, CO or separately listed in receipt notices | If USCIS directs you via notice or you reside in specific states | Follow instructions on notice, include check or money order |
Confirm Your Filing Eligibility Before Sending N-400
Before you decide where to send N-400, verify that you meet basic eligibility rules such as holding a green card for the required period, showing good moral character, and passing English and civics tests. Submitting to the wrong address can delay your case or result in a request for additional evidence.
Check the latest guidance on the official USCINS website if you recently moved, served in the military, or have prior enforcement actions. Following the correct process protects your personal information and supports smooth case processing.
Standard Address for Most Applicants
Using the National Lockbox in Texas
For the majority of U.S. based applicants, the recommended mailing address is the USCIS Austin Lockbox. This centralized facility handles a high volume of N-400 forms and is equipped to process receipts, checks, and biometric materials efficiently.
When you send your packet to this address, include a copy of your green card, any name change documentation, and a detailed list of enclosures as required on the form instructions.
Special Situations That Require Different Handling
Fingerprint Appointment Submissions
If your biometric appointment is scheduled before your N-400 is adjudicated, you may be instructed to submit directly to a regional USCIS Service Center. These centers accept your application, collect fingerprints, and forward materials to the adjudication team.
Always follow the specific instructions listed on your appointment notice to ensure your visit aligns with the submission requirements.
California Paper Filers
Applicants filing on paper who reside in California may be directed to the USCIS Intake Facility in Santa Rosa. This address is used when you receive a notice specifying that your case must go through this particular intake point.
Double-check your confirmation receipt or the instructions page of your N-400 to confirm whether this location applies to your situation.
How to Prepare Your Submission Packet
Correct packaging reduces the risk of lost documents and prevents processing delays. Use a sturdy envelope or flat-rate box, place a completed and signed N-400 on top, and arrange supporting materials in the order listed in the instructions.
Include payment via check or money order payable to USCIS, if required, and consider using trackable mail to monitor delivery. Keep copies of everything you send for your records.
Key Steps to Ensure Smooth Submission
- Confirm your eligibility using the latest USCIS naturalization criteria.
- Identify whether you qualify for online filing or paper submission.
- Use the correct address based on your filing method and residence.
- Organize all supporting documents in the order listed on the form instructions.
- Use trackable mailing methods and retain copies of your entire packet.
FAQ
Reader questions
Which address should I use if I am applying online?
When you file N-400 online, you do not need to mail the form yourself. After completing the application digitally, you will receive instructions for submitting biometric and supporting documents to the correct address, usually the Austin Lockbox.
What happens if I send my N-400 to the wrong address?
USCIS may return your packet, request resubmission, or redirect it to the correct location, which can slow down your case. Always verify the address on the latest version of the form instructions or on your appointment notice before mailing.
Do I need to include additional proof if I served in the U.S. military?
Yes, military applicants must include their service records, discharge documentation, and any related immigration documents with their N-400 submission, and these packets are often directed to special processing locations.
Can I submit my N-400 and supporting documents in person instead of by mail?
In most standard cases, N-400 applications must be mailed to the designated address. In-person drop-offs are limited to specific USCIS offices only when explicitly instructed, such as during certain military naturalization processes or asylum-related filings.