X12 276/277 STC Segment Guide: Fields, Format, and Testing Gotchas
A 276 inquiry is just a question. STC is the entire answer. Everything a front desk or a billing team actually wants to know — was the claim received, is it still in process, did it pay, did it deny, and why — collapses into one composite element and a handful of trailing fields. Get the composite wrong in a test file and your status-tracking screen shows a claim as paid when the payer never said any such thing.
STC (Status Information) is the segment in an X12 277 claim status response that carries the actual answer to a 276 inquiry. STC01 is a composite of two paired codes — a broad status category and a more specific status reason — and the rest of the segment adds the date the status became effective, an optional action code, and the total charge amount for the claim being described.
The elements that actually matter in practice
Example
A synthetic STC reporting F1 (Finalized/Payment) with reason code 1 (processed as primary), entity identifier PR (payer), effective 2026-07-28, on a claim originally billed at $450.00.
Where this trips people up
Test suites frequently treat STC as a single flat status flag and only ever populate the composite with one or two happy-path category/code pairs, usually something that maps cleanly to 'paid' or 'received.' That leaves pending statuses, partial denials, and multi-STC responses (a 277 can report status at both the claim level and the service-line level, each with its own STC segment) completely unexercised. A parser that only ever sees one STC segment per claim in test data will quietly mis-map the second one it encounters in production.