X12 276/277 Reference

X12 276/277 STC01-1 (Claim Status Category Code): Format, Values, and Testing Notes

Jul 27, 2026 · 4 min read

Front-end status screens live or die on STC01-1. Miss the difference between an acknowledgment category and a finalized category in test data and a claim that's merely been received starts showing up in a report meant for claims that have actually been adjudicated.

Quick answer

STC01-1 is the first component of the STC01 composite in an X12 277 response — a code from the shared HIPAA claim status category list that puts the status into one of a small number of broad buckets before STC01-2 narrows it down to a specific reason.

Valid code values

Acknowledgement/Receipt — the claim reached the payer, no adjudication decision yet

Acknowledgement/Acceptance — the claim passed initial edits and is in process

Pending — the claim is under review, often awaiting additional information

Finalized/Payment — the payer has adjudicated the claim and issued payment

Finalized/Denial — the payer has adjudicated the claim and denied it

Example

Synthetic example Generated by Synthibase

STC*F1:1:PR*20260728**450.00

F1 marks this claim as finalized with payment; STC01-2 (1) and STC01-3 (PR) narrow that down further. Synthetic status data.

Where this trips people up

A lot of synthetic 277 test files only ever generate F1 and F2 because those feel like the "real" outcomes worth testing. In production, a meaningful share of 277 responses come back as A1 or P1 while a claim is still moving through the payer's system, and a status-tracking UI that was only ever validated against finalized categories often has no defined state for "acknowledged" or "pending" and defaults to showing nothing at all.

→

X12 276/277 STC Segment Guide: Fields, Format, and Testing Gotchas

→

EDI 277 Claim Status: Format and Testing Guide

→

How to Reduce Claim Denials Through Better Pre-Submission Testing

Test every status category, not just paid and denied

Synthibase generates synthetic 277 responses spanning the full range of claim status categories, from acknowledgment through pending to finalized, so your status UI handles every state a payer can actually return.

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This page is written independently by Synthibase for testing and informational purposes. It is not an official publication of HL7 International or X12/Washington Publishing Company, and is not a substitute for reviewing the official standard or your trading partner's companion guide. See our Terms of Service for full legal terms.