Reference·N3 Segment·N301
X12 834 Reference

X12 834 N301 (Address Information): Format, Values, and Testing Notes

Jul 28, 2026 · 4 min read
N302 →

This field is free-form text, which means it's also the field most likely to contain something your parser wasn't expecting.

Quick answer

N301 is the primary street address line for whichever member the preceding NM1 segment identified. It's a required field whenever N3 appears in the loop, and unlike coded fields elsewhere in an 834, it's free-form text — so its content varies member to member rather than being drawn from a fixed list.

What this field needs to handle

719 MAPLE AVE
Standard street address — the common case — house or building number plus street name
PO BOX 4021
Post office box — a legitimate street-line value for members without a physical mailing address

Example

Synthetic example Generated by Synthibase
N3*719 MAPLE AVE*APT 4B

A synthetic N3 where N301=719 MAPLE AVE carries the street number and name for a member's mailing address.

Where this trips people up

Because N301 is free text rather than a coded value, generated test data tends to default to tidy, textbook-formatted addresses — always "NUMBER STREET NAME," always under twenty characters. Production files include PO boxes, rural route addresses, unusually long apartment complex names, and international-style formatting from members who moved abroad, all sitting in this same field. A parser or downstream mailing system tuned only to the tidy case can truncate long values or mishandle a PO box that doesn't fit the pattern it expects. Vary the length, format, and content of N301 in your test data instead of generating from one template.

How to Test X12 834 N3: A Field-by-Field Breakdown
EDI 834 Enrollment File: Format and Testing Guide
How to Write EDI Test Cases That Actually Catch Go-Live Failures
Test address variety your fixtures probably skip
Synthibase generates synthetic 834 files with N301 street lines that vary realistically in length and format — including PO boxes and unusual layouts — so address-handling logic gets tested against more than one clean template.
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